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  Subjects -> METEOROLOGY (Total: 90 journals)
Showing 1 - 36 of 36 Journals sorted alphabetically
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 33)
Advances in Climate Change Research     Open Access   (Followers: 8)
Advances in Meteorology     Open Access   (Followers: 18)
Advances in Statistical Climatology, Meteorology and Oceanography     Open Access   (Followers: 2)
Aeolian Research     Hybrid Journal   (Followers: 5)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 13)
American Journal of Climate Change     Open Access   (Followers: 13)
Atmósfera     Open Access   (Followers: 1)
Atmosphere     Open Access   (Followers: 21)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 12)
Atmospheric and Oceanic Science Letters     Open Access   (Followers: 1)
Atmospheric Chemistry and Physics (ACP)     Open Access   (Followers: 28)
Atmospheric Chemistry and Physics Discussions (ACPD)     Open Access   (Followers: 9)
Atmospheric Research     Hybrid Journal   (Followers: 54)
Atmospheric Science Letters     Open Access   (Followers: 28)
Boundary-Layer Meteorology     Hybrid Journal   (Followers: 22)
Bulletin of the American Meteorological Society     Open Access   (Followers: 31)
Carbon Balance and Management     Open Access   (Followers: 5)
Change and Adaptation in Socio-Ecological Systems     Open Access   (Followers: 1)
Climate     Open Access   (Followers: 2)
Climate Change Economics     Hybrid Journal   (Followers: 11)
Climate Change Responses     Open Access   (Followers: 3)
Climate Dynamics     Hybrid Journal   (Followers: 28)
Climate law     Hybrid Journal   (Followers: 4)
Climate of the Past (CP)     Open Access   (Followers: 4)
Climate of the Past Discussions (CPD)     Open Access   (Followers: 1)
Climate Policy     Hybrid Journal   (Followers: 28)
Climate Research     Hybrid Journal   (Followers: 5)
Climate Risk Management     Open Access  
Climate Services     Open Access  
Climate Summary of South Africa     Full-text available via subscription  
Climatic Change     Hybrid Journal   (Followers: 54)
Current Climate Change Reports     Hybrid Journal   (Followers: 3)
Developments in Atmospheric Science     Full-text available via subscription   (Followers: 15)
Dynamics and Statistics of the Climate System     Open Access   (Followers: 2)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 10)
Earth Perspectives - Transdisciplinarity Enabled     Open Access  
Energy & Environment     Full-text available via subscription   (Followers: 16)
Environmental and Climate Technologies     Open Access   (Followers: 3)
Global Meteorology     Open Access   (Followers: 6)
International Journal of Atmospheric Sciences     Open Access   (Followers: 23)
International Journal of Biometeorology     Hybrid Journal   (Followers: 1)
International Journal of Climate Change Strategies and Management     Hybrid Journal   (Followers: 13)
International Journal of Climatology     Hybrid Journal   (Followers: 24)
International Journal of Image and Data Fusion     Hybrid Journal   (Followers: 2)
Journal of Applied Meteorology and Climatology     Full-text available via subscription   (Followers: 25)
Journal of Atmospheric and Oceanic Technology     Full-text available via subscription   (Followers: 30)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 126)
Journal of Atmospheric Chemistry     Hybrid Journal   (Followers: 21)
Journal of Climate     Full-text available via subscription   (Followers: 39)
Journal of Hydrology and Meteorology     Open Access   (Followers: 14)
Journal of Hydrometeorology     Full-text available via subscription   (Followers: 5)
Journal of Integrative Environmental Sciences     Hybrid Journal   (Followers: 4)
Journal of Meteorology and Climate Science     Full-text available via subscription   (Followers: 7)
Journal of Space Weather and Space Climate     Open Access   (Followers: 19)
Journal of the Atmospheric Sciences     Full-text available via subscription   (Followers: 68)
Journal of the Meteorological Society of Japan     Partially Free   (Followers: 1)
Journal of Weather Modification     Full-text available via subscription   (Followers: 1)
Large Marine Ecosystems     Full-text available via subscription  
Mathematics of Climate and Weather Forecasting     Open Access   (Followers: 4)
Mediterranean Marine Science     Open Access   (Followers: 1)
Meteorologica     Open Access   (Followers: 1)
Meteorological Applications     Hybrid Journal   (Followers: 4)
Meteorologische Zeitschrift     Full-text available via subscription   (Followers: 2)
Meteorology and Atmospheric Physics     Hybrid Journal   (Followers: 20)
Mètode Science Studies Journal : Annual Review     Open Access  
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 5)
Monthly Notices of the Royal Astronomical Society Letters     Hybrid Journal   (Followers: 4)
Monthly Weather Review     Full-text available via subscription   (Followers: 25)
Nature Climate Change     Full-text available via subscription   (Followers: 59)
Nature Reports Climate Change     Full-text available via subscription   (Followers: 25)
Open Journal of Modern Hydrology     Open Access   (Followers: 4)
Revista Brasileira de Meteorologia     Open Access   (Followers: 1)
Revista Iberoamericana de Bioeconomía y Cambio Climático     Open Access  
Russian Meteorology and Hydrology     Hybrid Journal   (Followers: 3)
Space Weather     Full-text available via subscription   (Followers: 16)
Studia Geophysica et Geodaetica     Hybrid Journal   (Followers: 1)
Tellus A     Open Access   (Followers: 22)
Tellus B     Open Access   (Followers: 20)
The Cryosphere (TC)     Open Access   (Followers: 5)
The Cryosphere Discussions (TCD)     Open Access   (Followers: 3)
The Quarterly Journal of the Royal Meteorological Society     Hybrid Journal   (Followers: 21)
Theoretical and Applied Climatology     Hybrid Journal   (Followers: 6)
Urban Climate     Hybrid Journal  
Weather     Hybrid Journal   (Followers: 12)
Weather and Climate Extremes     Open Access   (Followers: 7)
Weather and Forecasting     Full-text available via subscription   (Followers: 15)
Weatherwise     Hybrid Journal   (Followers: 1)
气候与环境研究     Full-text available via subscription   (Followers: 1)
Journal Cover Journal of Atmospheric and Solar-Terrestrial Physics
  [SJR: 0.934]   [H-I: 70]   [126 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1364-6826
   Published by Elsevier Homepage  [3039 journals]
  • Rain attenuation statistics over millimeter wave bands in South Korea
    • Authors: Sujan Shrestha; Dong-You Choi
      Pages: 1 - 10
      Abstract: Publication date: January 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 152–153
      Author(s): Sujan Shrestha, Dong-You Choi
      Rain induced degradations are significant for terrestrial microwave links operating at frequencies higher than 10GHz. Paper presents analyses done on rain attenuation and rainfall data for three years between 2013 till 2015, in 3.2km experimental link of 38GHz and 0.1km link at 75GHz. The less link distance is maintained for 75GHz operating frequency in order to have better recording of propagation effect as such attenuation induced by rain. OTT Parsivel is used for collection of rain rate database which show rain rate of about 50mm/h and attenuation values of 20.89 and 28.55dB are obtained at 0.01% of the time for vertical polarization under 38 and 75GHz respectively. Prediction models, namely, ITU-R P. 530-16, Da Silva Mello, Moupfouma, Abdulrahman, Lin and differential equation approach are analyzed. This studies help to identify most suitable rain attenuation model for higher microwave bands. While applying ITU-R P. 530-16, the relative error margin of about 3%, 38% and 42% along with 80, 70, 61% were obtained in 0.1%, 0.01% and 0.001% of the time for vertical polarization under 38 and 75GHz respectively. Interestingly, ITU-R P. 530-16 shows relatively closer estimation to measured rain attenuation at 75GHz with relatively less error probabilities and additionally, Abdulrahman and ITU-R P. 530-16 results in better estimation to the measured rain attenuation at 38GHz link. The performance of prominent rain attenuation models are judged with different error matrices as recommended by ITU-R P. 311-15. Furthermore, the efficacy of frequency scaling technique of rain attenuation between links distribution are also discussed. This study shall be useful for making good considerations in rain attenuation predictions for terrestrial link operating at higher frequencies.

      PubDate: 2016-11-30T09:27:24Z
      DOI: 10.1016/j.jastp.2016.11.004
      Issue No: Vol. 152-153 (2016)
       
  • Statistical cloud coverage as determined from sunshine duration: a model
           applicable in daylighting and solar energy forecasting
    • Authors: Ladislav Kómar; Miroslav Kocifaj
      Pages: 1 - 8
      Abstract: Publication date: December 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 150–151
      Author(s): Ladislav Kómar, Miroslav Kocifaj
      A radiative/luminous energy budget is difficult to predict on a daily or hourly base if cloud coverage is obtained by subjective methods in discrete time points. A simple theoretical model that overcomes this shortcoming through interrelation of absolute cloud fraction and sunshine duration is presented. The latter is measured routinely at the meteorological stations worldwide. The model is based on statistical probability of clear line of sight, where Poisson spatial cloud distribution is analyzed for three different cloud shapes. A validation of the model using long-term measurements show a good correlation between experimentally determined and theoretically predicted data. The absolute cloud fraction obtained this way are a base for daylighting and solar energy applications including simulations of luminance/radiance sky distributions under different meteorological conditions. A simple calculation tool is developed and demonstrated on global horizontal illuminance (GHI).

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.011
      Issue No: Vol. 150-151 (2016)
       
  • Characterization of aerosol events based on the column integrated optical
           aerosol properties and polarimetric measurements
    • Authors: Florian Mandija; Krzysztof Markowicz; Olga Zawadzka
      Pages: 9 - 20
      Abstract: Publication date: December 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 150–151
      Author(s): Florian Mandija, Krzysztof Markowicz, Olga Zawadzka
      Aerosol optical properties are very useful tools for analyzing their radiative effects, which are directly or indirectly related to the global radiation budget. Investigation of column-integrated aerosol optical properties is a worldwide and well-accepted method. The introduction of new methodologies, like those of operation with polarimetric measurements, represent a new challenge to interpret the measurement data and give more detailed information about the aerosol events and their characteristics. Aerosol optical properties during the period June – August 2015 in AERONET Strzyzow station in Poland were analyzed. The aerosol properties like aerosol optical depth, Ångström exponent, fine mode fraction, fine mode contribution on AOD, asymmetry parameter, single scattering angle are analyzed synergistically with the polarimetric measurements of the degree of polarization in different solar zenith and zenith viewing angles at several wavelengths. The overall results show that aerosol events in Strzyzow were characterized mostly by fine mode aerosols. Backward-trajectories suggest that the majority of air masses come from the west. The principal component of the aerosol load was urban/industrial contamination, especially from the inner part of the continent. Additionally, the maximal values of the degree of linear polarization were found to be dependent on the solar zenith and zenith viewing angles and aerosol optical properties like aerosol optical depth and Ångström exponent. These dependencies were further analyzed in a specific case with very high mean values of AOD500 (0.59) and AE440–870 (1.91). The diurnal variations of aerosol optical properties investigated during this special case, suggest that biomass burning products are the main cause of that aerosol load over the stations.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.012
      Issue No: Vol. 150-151 (2016)
       
  • A scanning Raman lidar for observing the spatio-temporal distribution of
           water vapor
    • Authors: Masanori Yabuki; Makoto Matsuda; Takuji Nakamura; Taiichi Hayashi; Toshitaka Tsuda
      Pages: 21 - 30
      Abstract: Publication date: December 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 150–151
      Author(s): Masanori Yabuki, Makoto Matsuda, Takuji Nakamura, Taiichi Hayashi, Toshitaka Tsuda
      We have constructed a scanning Raman lidar to observe the cross-sectional distribution of the water vapor mixing ratio and aerosols near the Earth's surface, which are difficult to observe when a conventional Raman lidar system is used. The Raman lidar is designed for a nighttime operating system by employing a ultra-violet (UV) laser source and can measure the water vapor mixing ratio at an altitude up to 7km using vertically pointing observations. The scanning mirror system consists of reflective flat mirrors and a rotational stage. By using a program-controlled rotational stage, a vertical scan can be operated with a speed of 1.5°/s. The beam was pointed at 33 angles over range of 0–48° for the elevation angle with a constant step width of 1.5°. The range-height cross sections of the water vapor and aerosol within a 400m range can be obtained for 25min. The lidar signals at each direction were individually smoothed with the moving average to spread proportionally with the distance from the laser-emitting point. The averaged range at a distance of 200m (400m) from the lidar was 30.0m (67.5m) along the lidar signal in a specific direction. The experimental observations using the scanning lidar were conducted at night in the Shigaraki MU radar observatory located on a plateau with undulating topography and surrounded by forests. The root mean square error (RMSE) between the temporal variations of the water vapor mixing ratio by the scanning Raman lidar and by an in-situ weather sensor equipped with a tethered balloon was 0.17g/kg at an altitude of 100m. In cross-sectional measurements taken at altitudes and horizontal distances up to 400m from the observatory, we found that the water vapor mixing ratio above and within the surface layer varied vertically and horizontally. The spatio-temporal variability of water vapor near the surface seemed to be sensitive to topographic variations as well as the wind field and the temperature gradient over the site. From the wide-range cross-sectional observations of the water vapor mixing ratio and the backscatter ratio of aerosols within a 2000m range, we can detect small-scale water vapor structures on a horizontal scale of several hundred meters in the atmospheric boundary layer.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.013
      Issue No: Vol. 150-151 (2016)
       
  • The solar dimming/brightening effect over the Mediterranean Basin in the
           period 1979–2012
    • Authors: H.D. Kambezidis; D.G. Kaskaoutis; G.K. Kalliampakos; A. Rashki; M. Wild
      Pages: 31 - 46
      Abstract: Publication date: December 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 150–151
      Author(s): H.D. Kambezidis, D.G. Kaskaoutis, G.K. Kalliampakos, A. Rashki, M. Wild
      Numerous studies have shown that the solar radiation reaching the Earth's surface is subjected to multi-decadal variations with significant spatial and temporal heterogeneities in both magnitude and sign. Although several studies have examined the solar radiation trends over Europe, North America and Asia, the Mediterranean Basin has not been studied extensively. This work investigates the evolution and trends in the surface net short-wave radiation (NSWR, surface solar radiation - reflected) over the Mediterranean Basin during the period 1979–2012 using monthly re-analysis datasets from the Modern Era Retrospective-Analysis for Research and Applications (MERRA) and aims to shed light on the specific role of clouds on the NSWR trends. The solar dimming/brightening phenomenon is temporally and spatially analyzed over the Mediterranean Basin. The spatially-averaged NSWR over the whole Mediterranean Basin was found to increase in MERRA by +0.36Wm−2 per decade, with higher rates over the western Mediterranean (+0.82Wm−2 per decade), and especially during spring (March-April-May; +1.3Wm−2 per decade). However, statistically significant trends in NSWR either for all-sky or clean-sky conditions are observed only in May. The increasing trends in NSWR are mostly associated with decreasing ones in cloud optical depth (COD), especially for the low (<700hPa) clouds. The decreasing COD trends (less opaque clouds and/or decrease in absolute cloudiness) are more pronounced during spring, thus controlling the increasing tendency in NSWR. The NSWR trends for cloudless (clear) skies are influenced by changes in the water-vapor content or even variations in surface albedo to a lesser degree, whereas aerosols are temporally constant in MERRA. The slight negative trend (not statistically significant) in NSWR under clear skies for nearly all months and seasons implies a slight increasing trend in water vapor under a warming and more humid climatic scenario over the Mediterranean.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.006
      Issue No: Vol. 150-151 (2016)
       
  • Modelling the CO2 atmosphere-ocean flux in the upwelling zones using
           radiative transfer tools
    • Authors: Vladimir F. Krapivin; Costas A. Varotsos
      Pages: 47 - 54
      Abstract: Publication date: December 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 150–151
      Author(s): Vladimir F. Krapivin, Costas A. Varotsos
      An advanced mathematical model of the radiation forcing on the ocean surface is proposed for the assessment of the CO2 fluxes between atmosphere and ocean boundary in the upwelling zones. Two types of the upwelling are considered: coastal and local in the open ocean that are closely associated with changes in solar irradiance. The proposed model takes into account the maximal number of the carbon fluxes in the upwelling ecosystem considering that in the latter the only original source of energy and matter for all forms of life is the energy of the solar radiation. The vertical structure of the upwelling zone is represented by four levels: the upper mixed layer above the thermocline, the intermediate photic layer below the thermocline, the deep ocean and the near-bottom layer. Peruvian upwelling and typical local upwelling of tropical pelagic region are considered as examples for the model calculations.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.015
      Issue No: Vol. 150-151 (2016)
       
  • Point discharge current measurements beneath dust devils
    • Authors: Ralph D. Lorenz; Lynn D.V. Neakrase; John P. Anderson; R. Giles Harrison; Keri A. Nicoll
      Pages: 55 - 60
      Abstract: Publication date: December 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 150–151
      Author(s): Ralph D. Lorenz, Lynn D.V. Neakrase, John P. Anderson, R. Giles Harrison, Keri A. Nicoll
      We document for the first time observations of point discharge currents under dust devils using a novel compact sensor deployed in summer 2016 at the USDA-ARS Jornada Experimental Range in New Mexico, USA. A consistent signature is noted in about a dozen events seen over 40 days, with a positive current ramping up towards closest approach, switching to a decaying negative current as the devil recedes. The currents, induced on a small wire about 10cm above the ground, correlate with dust devil intensity (pressure drop) and dust loading, and reached several hundred picoAmps.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.017
      Issue No: Vol. 150-151 (2016)
       
  • Quantification of scaling exponents and dynamical complexity of microwave
           refractivity in a tropical climate
    • Authors: Ibiyinka A. Fuwape; Samuel T. Ogunjo
      Pages: 61 - 68
      Abstract: Publication date: December 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 150–151
      Author(s): Ibiyinka A. Fuwape, Samuel T. Ogunjo
      Radio refractivity index is used to quantify the effect of atmospheric parameters in communication systems. Scaling and dynamical complexities of radio refractivity across different climatic zones of Nigeria have been studied. Scaling property of the radio refractivity across Nigeria was estimated from the Hurst Exponent obtained using two different scaling methods namely: The Rescaled Range (R/S) and the detrended fluctuation analysis(DFA). The delay vector variance (DVV), Largest Lyapunov Exponent (λ 1) and Correlation Dimension (D 2) methods were used to investigate nonlinearity and the results confirm the presence of deterministic nonlinear profile in the radio refractivity time series. The recurrence quantification analysis (RQA) was used to quantify the degree of chaoticity in the radio refractivity across the different climatic zones. RQA was found to be a good measure for identifying unique fingerprint and signature of chaotic time series data. Microwave radio refractivity was found to be persistent and chaotic in all the study locations. The dynamics of radio refractivity increases in complexity and chaoticity from the Coastal region towards the Sahelian climate. The design, development and deployment of robust and reliable microwave communication link in the region will be greatly affected by the chaotic nature of radio refractivity in the region.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.010
      Issue No: Vol. 150-151 (2016)
       
  • Ball lightning passage through a glass without breaking it
    • Authors: Vladimir L. Bychkov; Anatoly I. Nikitin; Ilia P. Ivanenko; Tamara F. Nikitina; Alexander M. Velichko; Igor A. Nosikov
      Pages: 69 - 76
      Abstract: Publication date: December 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 150–151
      Author(s): Vladimir L. Bychkov, Anatoly I. Nikitin, Ilia P. Ivanenko, Tamara F. Nikitina, Alexander M. Velichko, Igor A. Nosikov
      In long history of ball lightning (BL) theory development there is a struggle of two concepts. According to the first one, BL – is a high frequency electrical discharge, burning in the air due to action of alternating electric field or a continuous current generated by an external source of energy. According to the second one, the BL is a material body, storing energy within itself. Data banks of BL observations give evidence that BL can pass through glasses, leaving no traces on them. Supporters of the first concept consider this as the proof of the correctness of the “electric field” BL nature. Representation of BL as a material body with internal source of energy explains most of its features, but has difficulties in explanation of BL penetration through glasses. We describe results of research of the glass, through which BL freely passed, that was observed by one of the authors. They proved the presence of traces left by BL. With a help of optical and scanning microscopes and laser beam probing of the glass, that experienced action of 20cm BL, we have found traces in it: in the glass we found a region of 1–2mm, at the center of which a cavity of 0.24mm diameter is located. This gives evidence to a “material” nature of BL. BL possibility to pass through small holes and its ability to “make” such holes poses a number of difficult issues to researchers indicated in the article.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.018
      Issue No: Vol. 150-151 (2016)
       
  • Mid-latitude mesospheric clouds and their environment from SOFIE
           observations
    • Authors: Mark E. Hervig; Michael Gerding; Michael H. Stevens; Robert Stockwell; Scott M. Bailey; James M. Russell; Gunter Stober
      Pages: 1 - 14
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Mark E. Hervig, Michael Gerding, Michael H. Stevens, Robert Stockwell, Scott M. Bailey, James M. Russell, Gunter Stober
      Observations from the Solar Occultation For Ice Experiment (SOFIE) on the Aeronomy of Ice in the Mesosphere (AIM) satellite are used to examine noctilucent clouds (NLC) and their environment at middle latitudes (~56°N and ~52°S). Because SOFIE is uniquely capable of measuring NLC, water vapor, and temperature simultaneously, the local cloud environment can be specified to examine what controls their formation at mid-latitudes. Compared to higher latitudes, mid-latitude NLCs are less frequent and have lower ice mass density, by roughly a factor of five. Compared to higher latitudes at NLC heights, mid-latitude water vapor is only ~12% lower while temperatures are more than 10K higher. As a result the reduced NLC mass and frequency at mid-latitudes can be attributed primarily to temperature. Middle and high latitude NLCs contain a similar amount of meteoric smoke, which was not anticipated because smoke abundance increases towards the equator in summer. SOFIE indicates that mid-latitude NLCs may or may not be associated with supersaturation with respect to ice. It is speculated that this situation is due in part to SOFIE uncertainties related to the limb measurement geometry combined with the non-uniform nature of NLCs. SOFIE is compared with concurrent NLC, temperature, and wind observations from Kühlungsborn, Germany (54°N) during the 2015 summer. The results indicate good agreement in temperature and NLC occurrence frequency, backscatter, and height. SOFIE indicates that NLCs were less frequent over Europe during 2015 compared to other longitudes, in contrast to previous years at higher latitudes that showed no clear longitude dependence. Comparisons of SOFIE and the Solar Backscatter Ultraviolet (SBUV) indicate good agreement in average ice water column (IWC), although differences in occurrence frequency were often large.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.09.004
      Issue No: Vol. 149 (2016)
       
  • Dependency of rain integral parameters on specific rain drop sizes and its
           seasonal behaviour
    • Authors: Saurabh Das; Debaleena Ghosh
      Pages: 15 - 20
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Saurabh Das, Debaleena Ghosh
      This paper investigates the variability of raindrop size distribution (DSD) and rain integral parameters at Ahmedabad, a tropical location, in relation to the radar estimation of rainfall. Rain DSDs for the years 2006–2007 at Ahmedabad (23°04′N, 72°38′E) have been measured using a disdrometer. Variability of DSD is evaluated for different seasons and its effect on the integral rain parameters like radar reflectivity, rainfall intensity and attenuation are examined. A percentage contribution of different drop diameters on rain integral parameters is studied to understand the seasonal behaviour of rain attenuation and radar reflectivity. It is observed that drops with diameter around 3mm contribute maximum to the radar reflectivity while drops having a diameter around 2mm contribute the maximum to the rainfall intensity for the present location. The critical diameter range responsible for the maximum contribution in rain attenuation found to shift towards large drops with an increase in rain rate for a fixed frequency. Linear and non-linear regression analysis between radar reflectivity and rainfall intensity show significant variations in different seasons but does not differ much for different regression techniques. Results point to the necessity of considering the seasonal variability of rain DSD in radar remote sensing and will be helpful for better characterizing of rain parameters from radar measurements.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.09.003
      Issue No: Vol. 149 (2016)
       
  • Wavelet neural networks using particle swarm optimization training in
           modeling regional ionospheric total electron content
    • Authors: Mir Reza Ghaffari Razin; Behzad Voosoghi
      Pages: 21 - 30
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Mir Reza Ghaffari Razin, Behzad Voosoghi
      Wavelet neural networks (WNNs) are a new class of neural networks (NNs) that has been developed using a combined method of multi-layer artificial neural networks and wavelet analysis (WA). In this paper, WNNs is used for modeling and prediction of total electron content (TEC) of ionosphere with high spatial and temporal resolution. Generally, back-propagation (BP) algorithm is used to train the neural network. While this algorithm proves to be very effective and robust in training many types of network structures, it suffers from certain disadvantages such as easy entrapment in a local minimum and slow convergence. To improve the performance of WNN in training step, the adjustment of network weights using particle swarm optimization (PSO) was proposed. The results obtained in this paper were compared with standard NN (SNN) by BP training algorithm (SNN-BP), SNN by PSO training algorithm (SNN-PSO) and WNN by BP training algorithm (WNN-BP). For numerical experiments, observations collected at 36 GPS stations in 5 days of 2012 from Iranian permanent GPS network (IPGN) are used. The average minimum relative errors in 5 test stations for WNN-PSO, WNN-BP, SNN-BP and SNN-PSO compared with GPS TEC are 10.59%, 12.85%, 13.18%, 13.75% and average maximum relative errors are 14.70%, 17.30%, 18.53% and 20.83%, respectively. Comparison of diurnal predicted TEC values from the WNN-PSO, SNN-BP, SNN-PSO and WNN-BP models with GPS TEC revealed that the WNN-PSO provides more accurate predictions than the other methods in the test area.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.09.005
      Issue No: Vol. 149 (2016)
       
  • Multifractal detrended fluctuation analysis of ionospheric total electron
           content data during solar minimum and maximum
    • Authors: E. Chandrasekhar; Sanjana S. Prabhudesai; Gopi K. Seemala; Nayana Shenvi
      Pages: 31 - 39
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): E. Chandrasekhar, Sanjana S. Prabhudesai, Gopi K. Seemala, Nayana Shenvi
      The spatio-temporal variations in ionospheric vertical total electron content (TEC) data, which often reflect their scale invariant properties, can well be studied with multifractal analysis. We discuss the multifractal behaviour of TEC recorded at a total of 27 stations confined to a narrow longitude band (35°W-80°W) spanning from equator to high-latitude regions (30°S to 80°N) (geographic coordinates) during solar minimum (2008) and solar maximum (2014), using multifractal detrended fluctuation analysis (MFDFA). MFDFA provides an understanding of the multifractal scaling behaviour of a signal using the multifractal singularity spectra and the generalised Hurst exponents as diagnostic tools. The objectives of this study are to (i) understand the latitudinal dependence of the multifractal behaviour of TEC, (ii) compare the multifractal behaviour of TEC corresponding to the well-known 27-day variation (solar rotation period) and its harmonics and the 1-day (solar diurnal) periodicities, during 2008 and 2014 and (iii) understand the lunar tidal influence on TEC. Results indicate that except for the 1-day period, the TEC at all other periods shows a higher degree of multifractality during solar maximum compared to solar minimum. Further, irrespective of the solar activity, the degree of mutifractality in general decreases with increase in period for all latitude zones for periods of 27-day and its harmonics. However, the 1-day period exhibits monofractal behaviour regardless of the solar activity. The influence of semi-lunar tidal effects (having a periodicity of about 14.5 days) as a function of latitude is clearly seen in the 13.5-day periodicity (i.e., the 2nd harmonic of 27-day variation) of TEC. It manifests in the form of decreasing differences in the widths of the multifractal singularity spectra corresponding to the years 2008 and 2014, with increase in latitude. Results are discussed in the light of these observations.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.09.007
      Issue No: Vol. 149 (2016)
       
  • A temperature error correction method for a naturally ventilated radiation
           shield
    • Authors: Jie Yang; Qingquan Liu; Wei Dai; Rrenhui Ding
      Pages: 40 - 45
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Jie Yang, Qingquan Liu, Wei Dai, Rrenhui Ding
      Due to solar radiation exposure, air flowing inside a naturally ventilated radiation shield may produce a measurement error of 0.8°C or higher. To improve the air temperature observation accuracy, a temperature error correction method is proposed. The correction method is based on a Computational Fluid Dynamics (CFD) method and a Genetic Algorithm (GA) method. The CFD method is implemented to analyze and calculate the temperature errors of a naturally ventilated radiation shield under various environmental conditions. Then, a temperature error correction equation is obtained by fitting the CFD results using the GA method. To verify the performance of the correction equation, the naturally ventilated radiation shield and an aspirated temperature measurement platform are characterized in the same environment to conduct the intercomparison. The aspirated temperature measurement platform serves as an air temperature reference. The mean temperature error given by measurements is 0.36°C, and the mean temperature error given by correction equation is 0.34°C. This correction equation allows the temperature error to be reduced by approximately 95%. The mean absolute error (MAE) and the root mean square error (RMSE) between the temperature errors given by the correction equation and the temperature errors given by the measurements are 0.07°C and 0.08°C, respectively.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.09.010
      Issue No: Vol. 149 (2016)
       
  • Phase synchronization between tropospheric radio refractivity and rainfall
           amount in a tropical region
    • Authors: Ibiyinka A. Fuwape; Samuel T. Ogunjo; Joseph B. Dada; Gabriel A. Ashidi; Israel Emmanuel
      Pages: 46 - 51
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Ibiyinka A. Fuwape, Samuel T. Ogunjo, Joseph B. Dada, Gabriel A. Ashidi, Israel Emmanuel
      This study investigated linear and nonlinear relationship between the amount of rainfall and radio refractivity in a tropical country, Nigeria using forty seven locations scattered across the country. Correlation and Phase synchronization measures were used for the linear and nonlinear relationship respectively. Weak correlation and phase synchronization was observed between seasonal mean rainfall amount and radio refractivity while strong phase synchronization was found for the detrended data suggesting similar underlying dynamics between rainfall amount and radio refractivity. Causation between rainfall and radio refractivity in a tropical location was studied using Granger causality test. In most of the Southern locations, rainfall was found to Granger cause radio refractivity. Furthermore, it was observed that there is strong correlation between mean rainfall amount and the phase synchronization index over Nigeria. Coupling between rainfall and radio refractivity has been found to be due to water vapour in the atmosphere. Frequency planning and budgeting for microwave propagation during periods of high rainfall should take into consideration this nonlinear relationship.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.09.009
      Issue No: Vol. 149 (2016)
       
  • The association between space weather conditions and emergency hospital
           admissions for myocardial infarction during different stages of solar
           activity
    • Authors: J. Vencloviene; J. Antanaitiene; R. Babarskiene
      Pages: 52 - 58
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): J. Vencloviene, J. Antanaitiene, R. Babarskiene
      A number of studies have established the effects of space weather on the human cardio-vascular system. We investigated whether geomagnetic storms (GS), solar proton events (SPEs), and X-class solar flare affect the risk of emergency hospitalization for acute myocardial infarction (MI) separately during declining (2004–2006) and rising (2010–2012) phases of solar activity. The data on hospital admissions for MI were obtained from the computer database of Lithuanian University of Health sciences from January 1, 2004 to December 31, 2012. We evaluated the associations between space weather conditions and the daily number of emergency admissions for MI by Poisson regression, controlling for seasonal variation and weekdays. During 2004–2006, an increase in the risk of hospital admission for MI was observed on days of the daily mean proton >10MeV flux >100pfu (by 63%, p<0.001) and on days of GS concomitant with SPE, 1–2 days following these events, and on days of SPE occurring 1–2 days before GS concomitant with SPE (by 26%, p=0.019). During 2010–2012, an increase in the risk of hospital admission for MI was observed on days of the daily mean proton >10MeV flux >100pfu (by 52%, p=0.015) and on days of GS and 1–2 days after GS (by 17%, p=0.024). These findings suggest that the impact of hazardous space weather conditions on human health depends of the strength of space storm during the investigated period.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.09.012
      Issue No: Vol. 149 (2016)
       
  • Preliminary observations and simulation of nocturnal variations of airglow
           temperature and emission rates at Pune (18.5°N), India
    • Authors: S. Fadnavis; W. Feng; Gordon G. Shepherd; J.M.C. Plane; S. Sonbawne; Chaitri Roy; S. Dhomse; S.D. Ghude
      Pages: 59 - 68
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): S. Fadnavis, W. Feng, Gordon G. Shepherd, J.M.C. Plane, S. Sonbawne, Chaitri Roy, S. Dhomse, S.D. Ghude
      Preliminary observations of the nocturnal variations of the OH(6-2) and O2b(0-1) nighttime airglow in the mesosphere and lower thermosphere are investigated in the context of tidal influence for the tropical latitude station Pune (18.5°N, 73.85°E). This is the only tropical Spectral Airglow Temperature Imager (SATI) station where the tidal variations of mesosphere and lower thermosphere (MLT) temperature have been determined from ground based SATI observations. The SATI observations obtained since October 2012 reveal the influence of the migrating semidiurnal tides during solstice at this tropical station. There is variability in amplitude and phase obtained from SATI observations. In this paper, SATI observations on 10 Dec 2012 and 3 March 2013 are compared with Whole Atmosphere Community Climate Model (WACCM) simulations. The amplitude of semidiurnal tides is ~25K/30K on 10 Dec 2012 during solstice for OH/O2 temperature. During equinox SATI data indicates existence of semidiurnal tide also. The airglow observations are compared with simulations from the WACCM. The model underestimates the amplitude of the semi diurnal tide during equinox (1.6K/2.7K at 87km/96km) and solstice (~3.8K/4.8K at 87km/96km) for these days. The reason may be related to dampening of tides in the model due to the effect of strong latitudinal shear in zonal wind. The diurnal variation of airglow emission – which the model simulates well – is related to the vertical advection associated with the tides and downward mixing of atomic oxygen.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.002
      Issue No: Vol. 149 (2016)
       
  • Performance assessment of different day-of-the-year-based models for
           estimating global solar radiation - Case study: Egypt
    • Authors: Gasser E. Hassan; M. Elsayed Youssef; Mohamed A. Ali; Zahraa E. Mohamed; Ali I. Shehata
      Pages: 69 - 80
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Gasser E. Hassan, M. Elsayed Youssef, Mohamed A. Ali, Zahraa E. Mohamed, Ali I. Shehata
      Different models are introduced to predict the daily global solar radiation in different locations but there is no specific model based on the day of the year is proposed for many locations around the world. In this study, more than 20 years of measured data for daily global solar radiation on a horizontal surface are used to develop and validate seven models to estimate the daily global solar radiation by day of the year for ten cities around Egypt as a case study. Moreover, the generalization capability for the best models is examined all over the country. The regression analysis is employed to calculate the coefficients of different suggested models. The statistical indicators namely, RMSE, MABE, MAPE, r and R2 are calculated to evaluate the performance of the developed models. Based on the validation with the available data, the results show that the hybrid sine and cosine wave model and 4th order polynomial model have the best performance among other suggested models. Consequently, these two models coupled with suitable coefficients can be used for estimating the daily global solar radiation on a horizontal surface for each city, and also for all the locations around the studied region. It is believed that the established models in this work are applicable and significant for quick estimation for the average daily global solar radiation on a horizontal surface with higher accuracy. The values of global solar radiation generated by this approach can be utilized in the design and estimation of the performance of different solar applications.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.09.011
      Issue No: Vol. 149 (2016)
       
  • A study on the main periodicities in interplanetary magnetic field Bz
           component and geomagnetic AE index during HILDCAA events using wavelet
           analysis
    • Authors: A.M. Souza; E. Echer; M.J.A. Bolzan; R. Hajra
      Pages: 81 - 86
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): A.M. Souza, E. Echer, M.J.A. Bolzan, R. Hajra
      The interplanetary and geomagnetic characteristics of High-Intensity Long-Duration Continuous AE Activity (HILDCAA) events are studied using wavelet analysis technique. The Morlet wavelet transform was applied to the 1min interplanetary magnetic field (IMF) Bz component and the geomagnetic AE index during HILDCAA events. We have analyzed the AE data for the events occurring between 1975 and 2011, and the IMF Bz data (both in GSE and GSM) for the events between 1995 and 2011. We analyzed the scalograms and the global wavelet spectrum of the parameters. For 50% of all HILDCAA events, the main periodicities of the AE index are generally between 4 and 12h. For the Bz component, the main periodicities were found to be less than 8h for ~56% of times in GSM system and for ~54% of times in GSE system. It is conjectured that the periodicities might be associated with the Alfvén waves which have typical periods between 1 and 10h. The results are discussed in the light of self organized criticality theory where the physical events have the capacity of releasing a considerable amount of energy in a short interval of time.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.09.006
      Issue No: Vol. 149 (2016)
       
  • Balloon measurements of the vertical ionization profile over southern
           Israel and comparison to mid-latitude observations
    • Authors: Roy Yaniv; Yoav Yair; Colin Price; Keri Nicoll; Giles Harrison; Anton Artamonov; Ilya Usoskin
      Pages: 87 - 92
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Roy Yaniv, Yoav Yair, Colin Price, Keri Nicoll, Giles Harrison, Anton Artamonov, Ilya Usoskin
      Airborne measurements using meteorological balloons were conducted for the first time from southern Israel (geographic 30°35’N, 34°45’E geomagnetic 27°6’N 112°23’E) for measuring the vertical ionization profile during solar cycle 24. The results show the differences (increase of ~30%) in count rates as we proceed from solar maximum toward solar minimum. The observed altitude of maximum ionization (the Regener-Pfotzer maximum) was between 17–20km, and it agrees well with results from other simultaneous measurements conducted at different latitudes (Reading, UK and Zaragoza-Barcelona, Spain). When compared with predictions of an analytical model, we find a highly significant correlation (R2=0.97) between our observations and the computed ionization profiles. The difference in count rates can be attributed to the height of the tropopause due to the model using a US standard atmosphere that differs from the measured atmospheric parameters above Israel.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.003
      Issue No: Vol. 149 (2016)
       
  • Spatial and temporal variability of the atmospheric turbidity in Tunisia
    • Authors: Mohamed Saad; Amel Trabelsi; Mohamed Masmoudi; Stephane C. Alfaro
      Pages: 93 - 99
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Mohamed Saad, Amel Trabelsi, Mohamed Masmoudi, Stephane C. Alfaro
      Atmospheric turbidity is an important parameter in meteorology, climatology and for providing hindsight on particulate air pollution in local areas. In this work we exploit 1260 direct solar radiation measurements performed in Sfax (Center Tunisia), from March 2015 to February 2016. These measurements were made with a pyrheliometer only when clouds did not obstruct the solar disk. The atmospheric turbidity is quantified by the means of both the Linke's turbidity factor (T LI ) and Angström's coefficient (β). Over the year, values of T LI and β are found to vary in the ranges 1–15 and 0–0.7, with the most probable values around 3.5 and 0.05, respectively. However, a marked seasonal pattern is observed for the two turbidity parameters. They achieve their maximum in the spring and summer months, their minimum in winter and autumn appears as a transitional period. The comparison of the results obtained in Sfax with those of three AERONET stations located in north (Carthage), central-north (Ben Salem), and south (Medenine) Tunisia, reveals that this seasonal pattern of the atmospheric turbidity is valid for all the Tunisian territory, and probably beyond. At shorter (hourly) time scales, the diurnal behavior of the turbidity in Sfax is different in the summer months from the one observed during the rest of the year. Indeed, an enhancement of T LI is observed during the day. This is assumedly attributed to the production of secondary aerosols by atmospheric photochemistry.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.001
      Issue No: Vol. 149 (2016)
       
  • Temporal and spatial characteristics of lightning-produced nitrogen oxides
           in China
    • Authors: Guo Fengxia; Bao Min; Mu Yijun; Liu Zupei; Li Yawen; Shi Haifeng
      Pages: 100 - 107
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Guo Fengxia, Bao Min, Mu Yijun, Liu Zupei, Li Yawen, Shi Haifeng
      Tropospheric NO2 vertical column densities (NO2VCDs) retrieved from the Global Ozone Monitoring Experiment-2 satellite spectrometer, as well as lightning flashes measured by an Optical Transient Detector and Lightning Image Sensor from 1997 to 2013 are used to investigate spatial and temporal characteristics of lightning-produced nitrogen oxides (LNOX) under the recent period of rapid and locally-unbalanced economic development in China. Correlations between spatial distributions of lightning flashes and monthly mean tropospheric NO2VCDs were analyzed over this period. Mean production of LNOX per flash is 330mol[N]/flash which was estimated using the correlation between lightning flashes and monthly mean tropospheric NO2VCD for the Tibetan Plateau. Using this correlation, the spatial and temporal characteristics of the ratio of LNOX to tropospheric NOX in China were determined. Results show that the ratio of LNOX to the tropospheric NOX is small in eastern regions, having a developed industrial sector and dense population, but relatively large in western regions, with a developing industrial sector and sparser population. The annual mean value of LNOX contributing to tropospheric NOX is 7.5% in China, which is lower than global averages (10–20%). The difference in interannual variability of LNOX production contributing to tropospheric NOX in different areas is distinct, ranging from high to low values for the Tibetan Plateau, Pearl River Delta, Yangtze River Delta and Beijing–Tianjin–Hebei regions, respectively. This indicates that lightning had a large influence on the column density of tropospheric NOX on the Tibetan Plateau, a region typically used as a sensitivity indicator for climate change. Lightning had less influence on atmospheric environments of the Pearl River Delta, Yangtze River Delta and Beijing–Tianjin–Hebei regions.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.007
      Issue No: Vol. 149 (2016)
       
  • Vertical winds and momentum fluxes due to equatorial planetary scale waves
           using all-sky meteor radar over Brazilian region
    • Authors: F. Egito; V.F. Andrioli; P.P. Batista
      Pages: 108 - 119
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): F. Egito, V.F. Andrioli, P.P. Batista
      In the equatorial region planetary scale waves play an important role transporting significant amount of energy and momentum through atmosphere. Quantifying the momentum transported by these waves and its effects on the mean flow is rather important. Direct estimates of the momentum flux transported by waves require horizontal and vertical wind measurements. Ground-based meteor radars have provided continuous and reliable measurements of the horizontal wind components in the Mesosphere and Lower Thermosphere (MLT) region and have contributed to improve our knowledge of the dynamics of this region. However, instrumental limitations hinder its use for measuring vertical winds and momentum fluxes. On the other hand, according to Babu et al (2012), all- sky meteor radars are able to infer tridimensional winds when using a large number of meteor echoes centered at the meteor ablation peak. Following this approach, we have used measurements performed by a Meteor Radar installed at São João do Cariri, Brazil (7.4°S; 36.5°W) in order to measure vertical winds and calculate the momentum flux transported by equatorial planetary scale waves. In order to evaluate the accuracy of vertical wind values we have performed several tests based on a simple model considering real meteor distributions and theoretical equations for the MLT winds motion. From our tests, we inferred that Brazilian meteor radar data can be used for this purpose with an accuracy of ~ 1.8m/s. The results show that the vertical wind presents magnitudes of a few meters per second and occasionally reaches magnitudes around 10m/s. Below 92km the vertical wind is predominantly upward during the whole year and above exhibits a semi-annual oscillation with downward phase during the equinoxes. Variations associated to planetary scale waves in the vertical wind are also observed and some of them appear simultaneously in the zonal and meridional wind as well. Largest wave induced amplitudes in the vertical wind are found in the 3–4d band, reaching up to 4m/s. From the vertical and zonal wind measurements, we calculated the vertical transport of zonal momentum in the 3–4d band and found it to be maximum near autumn equinox, when its value reaches almost 20m2/s2, while minimum momentum flux is observed after the winter solstice.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.005
      Issue No: Vol. 149 (2016)
       
  • Receiver DCB estimation and GPS vTEC study at a low latitude station in
           the South Pacific
    • Authors: Ramendra Prasad; Sushil Kumar; P.T. Jayachandran
      Pages: 120 - 130
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Ramendra Prasad, Sushil Kumar, P.T. Jayachandran
      The statistical estimation of receiver differential code bias (DCB) of the GSV4004B receiver at a low latitude station, Suva (lat. 18.15°S, long. 178.45°E, Geomag. Lat. 21.07°S), Fiji, and the subsequent behaviour of vTEC, are presented. By means of least squares linear regression fitting technique, the receiver DCB was determined using the GPS vTEC data recorded during the year 2010, CODE TEC and IRI-2012 model for 2010. To substantiate the results, minimization of the standard deviation (SD) method was also used for GPS vTEC data. The overall monthly DCB was estimated to be in the range of 62.6 TECU. The vTEC after removing the resultant monthly DCB was consistent with other low latitude observations. The GPS vTEC 2010 data after eliminating the resultant DCB were lower in comparison to Faraday rotation vTEC measurements at Suva during 1984 primarily due to higher solar activity during 1984 as compared to 2010. Seasonally, vTEC was maximum during summer and minimum during winter. The winter showed least vTEC variability whereas equinox showed the largest daytime variability. The geomagnetic disturbances effect showed that both vTEC and its variability were higher on magnetically disturbed days as compared to quiet days with maximum variability in the daytime. Two geomagnetic storms of moderate strengths with main phases in the local daytime showed long duration (∼52h) increase in vTEC by 33–67% which can be accounted by changes in E×B drifts due to prompt penetration of storm-time auroral electric field in the daytime and disturbance dynamo electric field in the nighttime to low latitudes.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.004
      Issue No: Vol. 149 (2016)
       
  • Estimation of daily global solar radiation using wavelet regression, ANN,
           GEP and empirical models: A comparative study of selected
           temperature-based approaches
    • Authors: Sayed Saber Sharifi; Vahid Rezaverdinejad; Vahid Nourani
      Pages: 131 - 145
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Sayed Saber Sharifi, Vahid Rezaverdinejad, Vahid Nourani
      Although the sunshine-based models generally have a better performance than temperature-based models for estimating solar radiation, the limited availability of sunshine duration records makes the development of temperature-based methods inevitable. This paper presents a comparative study between Artificial Neural Networks (ANNs), Gene Expression Programming (GEP), Wavelet Regression (WR) and 5 selected temperature-based empirical models for estimating the daily global solar radiation. A new combination of inputs including four readily accessible parameters have been employed: daily mean clearness index (KT), temperature range (ΔT), theoretical sunshine duration (N) and extraterrestrial radiation (Ra). Ten statistical indicators in a form of GPI (Global Performance Indicator) is used to ascertain the suitability of the models. The performance of selected models across the range of solar radiation values, was depicted by the quantile-quantile (Q-Q) plots. Comparing these plots makes it evident that ANNs can cover a broader range of solar radiation values. The results shown indicate that the performance of ANN model was clearly superior to the other models. The findings also demonstrated that WR model performed well and presented high accuracy in estimations of daily global solar radiation.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.008
      Issue No: Vol. 149 (2016)
       
  • Foreword: Special issue on “Effects of the solar wind and interplanetary
           disturbances on the Earth's atmosphere and climate”
    • Authors: E. Rozanov; K. Georgieva; I. Mironova; B. Tinsley; A. Aylward
      Pages: 146 - 150
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): E. Rozanov, K. Georgieva, I. Mironova, B. Tinsley, A. Aylward
      The special issue “Effects of the solar wind and interplanetary disturbances on the Earth's atmosphere and climate” discusses the effects of solar wind and interplanetary disturbances on the Earth's atmosphere and climate. After a brief introduction to the solar wind and its geoeffective agents, the results presented in the special issue are highlighted, which include both statistical studies aimed at the identification of atmosphere and climate response to external solar forcing, and attempts to identify responsible physical mechanisms and include some of them in climate models.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.08.012
      Issue No: Vol. 149 (2016)
       
  • Ionosphere dynamics in the auroral zone during the magnetic storm of March
           17–18, 2015
    • Authors: D.V. Blagoveshchensky; M.A. Sergeeva
      Pages: 151 - 160
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): D.V. Blagoveshchensky, M.A. Sergeeva
      A comprehensive study of the ionospheric processes encountered during the superstorm which started on March 17th 2015 has been carried out using magnetometer, ionosonde, riometer, ionospheric tomography and an all-sky camera installed in the observatory of Sodankylä, Finland. The storm manifested a number of interesting features. From 12:00 on March 17 there was a significant decrease of critical frequencies foF2 and intensive sporadic Es layers were observed. During the disturbance, there was a lack of variation of the X-component of the magnetic field at times, but the absorption level measured by the riometer was high. A comparison of the electron density distributions for the quiet and disturbed days as shown in the tomography data were very different. Where results were available at the same times, the tomographic foF2 values coincided with the “real” foF2 values from the ionosonde. Where the ionosonde data was missing due to absorption, the tomographic foF2 values were used instead. The keograms from the all-sky camera showed that during disturbed days the aurorae manifested themselves as bright discrete forms. It was shown that the peaks of absorption due to particle precipitation seen by the riometer coincided in time with the brightenings of aurorae seen on the keograms.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.06.016
      Issue No: Vol. 149 (2016)
       
  • Comparing the influence of sunspot activity and geomagnetic activity on
           winter surface climate
    • Authors: I. Roy; T. Asikainen; V. Maliniemi; K. Mursula
      Pages: 167 - 179
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): I. Roy, T. Asikainen, V. Maliniemi, K. Mursula
      We compare here the effect of geomagnetic activity (using the aa index) and sunspot activity on surface climate using sea level pressure dataset from Hadley centre during northern winter. Previous studies using the multiple linear regression method have been limited to using sunspots as a solar activity predictor. Sunspots and total solar irradiance indicate a robust positive influence around the Aleutian Low. This is valid up to a lag of one year. However, geomagnetic activity yields a positive NAM pattern at high to polar latitudes and a positive signal around Azores High pressure region. Interestingly, while there is a positive signal around Azores High for a 2-year lag in sunspots, the strongest signal in this region is found for aa index at 1-year lag. There is also a weak but significant negative signature present around central Pacific for both sunspots and aa index. The combined influence of geomagnetic activity and Quasi Biannual Oscillation (QBO 30hPa) produces a particularly strong response at mid to polar latitudes, much stronger than the combined influence of sunspots and QBO, which was mostly studied in previous studies so far. This signal is robust and insensitive to the selected time period during the last century. Our results provide a useful way for improving the prediction of winter weather at middle to high latitudes of the northern hemisphere.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.04.009
      Issue No: Vol. 149 (2016)
       
  • The influence of Middle Range Energy Electrons on atmospheric chemistry
           and regional climate
    • Authors: P. Arsenovic; E. Rozanov; A. Stenke; B. Funke; J.M. Wissing; K. Mursula; F. Tummon; T. Peter
      Pages: 180 - 190
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): P. Arsenovic, E. Rozanov, A. Stenke, B. Funke, J.M. Wissing, K. Mursula, F. Tummon, T. Peter
      We investigate the influence of Middle Range Energy Electrons (MEE; typically 30-300keV) precipitation on the atmosphere using the SOCOL3-MPIOM chemistry-climate model with coupled ocean. Model simulations cover the 2002-2010 period for which ionization rates from the AIMOS dataset and atmospheric composition observations from MIPAS are available. Results show that during geomagnetically active periods MEE significantly increase the amount of NO y and HO x in the polar winter mesosphere, in addition to other particles and sources, resulting in local ozone decreases of up to 35%. These changes are followed by an intensification of the polar night jet, as well as mesospheric warming and stratospheric cooling. The contribution of MEE also substantially enhances the difference in the ozone anomalies between geomagnetically active and quiet periods. Comparison with MIPAS NO y observations indicates that the additional source of NO y from MEE improves the model results, however substantial underestimation above 50km remains and requires better treatment of the NO y source from the thermosphere. A surface air temperature response is detected in several regions, with the most pronounced warming occurring in the Antarctic during austral winter. Surface warming of up to 2K is also seen over continental Asia during boreal winter.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.04.008
      Issue No: Vol. 149 (2016)
       
  • Particle precipitation: How the spectrum fit impacts atmospheric chemistry
    • Authors: J.M. Wissing; H. Nieder; O.S. Yakovchouk; M. Sinnhuber
      Pages: 191 - 206
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): J.M. Wissing, H. Nieder, O.S. Yakovchouk, M. Sinnhuber
      Particle precipitation causes atmospheric ionization. Modeled ionization rates are widely used in atmospheric chemistry/climate simulations of the upper atmosphere. As ionization rates are based on particle measurements some assumptions concerning the energy spectrum are required. While detectors measure particles binned into certain energy ranges only, the calculation of a ionization profile needs a fit for the whole energy spectrum. Therefore the following assumptions are needed: (a) fit function (e.g. power-law or Maxwellian), (b) energy range, (c) amount of segments in the spectral fit, (d) fixed or variable positions of intersections between these segments. The aim of this paper is to quantify the impact of different assumptions on ionization rates as well as their consequences for atmospheric chemistry modeling. As the assumptions about the particle spectrum are independent from the ionization model itself the results of this paper are not restricted to a single ionization model, even though the Atmospheric Ionization Module OSnabrück (Aimos, Wissing and Kallenrode, 2009) is used here. We include protons only as this allows us to trace changes in the chemistry model directly back to the different assumptions without the need to interpret superposed ionization profiles. However, since every particle species requires a particle spectrum fit with the mentioned assumptions the results are generally applicable to all precipitating particles. The reader may argue that the selection of assumptions of the particle fit is of minor interest, but we would like to emphasize on this topic as it is a major, if not the main, source of discrepancies between different ionization models (and reality). Depending on the assumptions single ionization profiles may vary by a factor of 5, long-term calculations may show systematic over- or underestimation in specific altitudes and even for ideal setups the definition of the energy-range involves an intrinsic 25% uncertainty for the ionization rates. The effects on atmospheric chemistry (HO x , NO x and Ozone) have been calculated by 3dCTM, showing that the spectrum fit is responsible for a 8% variation in Ozone between setups, and even up to 50% for extreme setups.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.04.007
      Issue No: Vol. 149 (2016)
       
  • Cloud cover anomalies at middle latitudes: Links to troposphere dynamics
           and solar variability
    • Authors: S. Veretenenko; M. Ogurtsov
      Pages: 207 - 218
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): S. Veretenenko, M. Ogurtsov
      In this work we study links between low cloud anomalies (LCA) at middle latitudes of the Northern and Southern hemispheres and galactic cosmic ray (GCR) variations used as a proxy of solar variability on the decadal time scale. It was shown that these links are not direct, but realized through GCR/solar activity phenomena influence on the development of extratropical baric systems (cyclones and troughs) which form cloud field. The violation of a positive correlation between LCA and GCR intensity which was observed in the 1980s–1990s occurred simultaneously in the Northern and Southern hemispheres in the early 2000s and coincided with the sign reversal of GCR effects on troposphere circulation. It was suggested that a possible reason for the correlation reversal between cyclonic activity at middle latitudes and GCR fluxes is the change of the stratospheric polar vortex intensity which influences significantly the troposphere-stratosphere coupling. The evidences for a noticeable weakening of the polar vortices in the Arctic and Antarctic stratosphere in the early 2000s are provided. The results obtained suggest an important role of the polar vortex evolution as a reason for a temporal variability of solar activity effects on the lower atmosphere.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.04.003
      Issue No: Vol. 149 (2016)
       
  • A link between high-speed solar wind streams and explosive extratropical
           cyclones
    • Authors: Paul Prikryl; Koki Iwao; Donald B. Muldrew; Vojto Rušin; Milan Rybanský; Robert Bruntz
      Pages: 219 - 231
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Paul Prikryl, Koki Iwao, Donald B. Muldrew, Vojto Rušin, Milan Rybanský, Robert Bruntz
      A link between solar wind magnetic sector boundary (heliospheric current sheet) crossings by the Earth and the upper-level tropospheric vorticity was discovered in the 1970s. These results have been later confirmed but the proposed mechanisms remain controversial. Extratropical-cyclone tracks obtained from two meteorological reanalysis datasets are used in superposed epoch analysis of time series of solar wind plasma parameters and green coronal emission line intensity. The time series are keyed to times of maximum growth of explosively developing extratropical cyclones in the winter season. The new statistical evidence corroborates the previously published results (Prikryl et al., 2009). This evidence shows that explosive extratropical cyclones tend to occur after arrivals of solar wind disturbances such as high-speed solar wind streams from coronal holes when large amplitude magneto-hydrodynamic waves couple to the magnetosphere-ionosphere system. These MHD waves modulate Joule heating and/or Lorentz forcing of the high-latitude thermosphere generating medium-scale atmospheric gravity waves that propagate energy upward and downward from auroral zone through the atmosphere. At the tropospheric level, in spite of significantly reduced amplitudes, these gravity waves can provide a lift of unstable air to release the moist symmetric instability thus initiating slantwise convection and forming cloud/precipitation bands. The release of latent heat is known to provide energy for rapid development and intensification of extratropical cyclones.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.04.002
      Issue No: Vol. 149 (2016)
       
  • Correlations of global sea surface temperatures with the solar wind speed
    • Authors: Limin Zhou; Brian Tinsley; Huimin Chu; Ziniu Xiao
      Pages: 232 - 239
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Limin Zhou, Brian Tinsley, Huimin Chu, Ziniu Xiao
      A significant correlation between the solar wind speed (SWS) and sea surface temperature (SST) in the region of the North Atlantic Ocean has been found for the Northern Hemisphere winter from 1963 to 2010, based on 3-month seasonal averages. The correlation is dependent on B z (the interplanetary magnetic field component parallel to the Earth's magnetic dipole) as well as the SWS, and somewhat stronger in the stratospheric quasi-biennial oscillation (QBO) west phase than in the east phase. The correlations with the SWS are stronger than those with the F10.7 parameter representing solar UV inputs to the stratosphere. SST responds to changes in tropospheric dynamics via wind stress, and to changes in cloud cover affecting the radiative balance. Suggested mechanisms for the solar influence on SST include changes in atmospheric ionization and cloud microphysics affecting cloud cover, storm invigoration, and tropospheric dynamics. Such changes modify upward wave propagation to the stratosphere, affecting the dynamics of the polar vortex. Also, direct solar inputs, including energetic particles and solar UV, produce stratospheric dynamical changes. Downward propagation of stratospheric dynamical changes eventually further perturbs tropospheric dynamics and SST.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.02.010
      Issue No: Vol. 149 (2016)
       
  • The role of climatic forcings in variations of Portuguese temperature: A
           comparison of spectral and statistical methods
    • Authors: Anna L. Morozova; Tatiana V. Barlyaeva
      Pages: 240 - 257
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Anna L. Morozova, Tatiana V. Barlyaeva
      Monthly series of temperature parameters measured by three Portuguese meteorological stations from 1888 to 2001 were used to study the effect of different climatic forcings. Three types of external forcings were considered: anthropogenic greenhouse gases and aerosols, volcanic aerosols, and solar and geomagnetic activity variations. Long-term variations of the temperature and other parameters with characteristic periods of decades were studied by various methods including the seasonal-trend decomposition based on LOESS (LOcally wEighted regreSSion), correlation and multiple regression analyses, and wavelet/wavelet coherence analyses. Obtained results confirm the statistical dependence of the temperature variations on the volcanic and the anthropogenic influence as well as variability that can be associated with the solar activity impact. In particular, surprisingly strong bi-decadal cycles were observed in temperature series whereas the observed decadal cycles are weaker and transient. Another interesting finding is the apparent non-stationarity of the relations between the solar and atmospheric parameters probably related to periods of strong/weak global circulation or frequent/occasional volcanic eruptions or interaction between the external forcing and internal atmospheric variability.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.02.006
      Issue No: Vol. 149 (2016)
       
  • Catalogue of electron precipitation events as observed in the
           long-duration cosmic ray balloon experiment
    • Authors: V.S. Makhmutov; G.A. Bazilevskaya; Yu.I. Stozhkov; A.K. Svirzhevskaya; N.S. Svirzhevsky
      Pages: 258 - 276
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): V.S. Makhmutov, G.A. Bazilevskaya, Yu.I. Stozhkov, A.K. Svirzhevskaya, N.S. Svirzhevsky
      Since the International Geophysical Year (1957), the Lebedev Physical Institute performs the regular measurements of charged particle fluxes in the Earth's atmosphere (from the ground level up to 30–35km) at several latitudes. The unique experimental data base obtained during 58 years of cosmic rays observations in the atmosphere allows to investigate temporal, spatial and energetic characteristics of galactic and solar cosmic rays as well as the role of charged particles in the atmospheric processes. Analysis of this data base also revealed a special class of numerous events caused by energetic electron precipitation recorded in the atmosphere at polar latitudes. In this paper we present Catalogue of electron precipitation events observed in the polar atmosphere during 1961–2014 and briefly outline the previous results of this data set analysis.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2015.12.006
      Issue No: Vol. 149 (2016)
       
  • Solar wind-atmospheric electricity-cloud microphysics connections to
           weather and climate
    • Authors: Mai Mai Lam; Brian A. Tinsley
      Pages: 277 - 290
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): Mai Mai Lam, Brian A. Tinsley
      We review recent research articles that present observations of the large-scale day-to-day dynamic tropospheric response to changes in the downward current density J z of the global atmospheric electric circuit (GEC). The evidence for the global circuit downward current density, J z , causing changes in atmospheric dynamics is now even stronger than as reviewed by Tinsley (2008) (Rep. Prog. Phys. 71, 066801). We consider proposed mechanisms for these responses, and suggest future directions for research.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2015.10.019
      Issue No: Vol. 149 (2016)
       
  • Relevance of long term time – Series of atmospheric parameters at a
           mountain observatory to models for climate change
    • Authors: M. Kancírová; K. Kudela; A.D. Erlykin; A.W. Wolfendale
      Pages: 1 - 12
      Abstract: Publication date: October 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 148
      Author(s): M. Kancírová, K. Kudela, A.D. Erlykin, A.W. Wolfendale
      A detailed analysis has been made based on annual meteorological and cosmic ray data from the Lomnicky stit mountain observatory (LS, 2634 masl; 49.40°N, 20.22°E; vertical cut-off rigidity 3.85GV), from the standpoint of looking for possible solar cycle (including cosmic ray) manifestations. A comparison of the mountain data with the Global average for the cloud cover in general shows no correlation but there is a possible small correlation for low clouds (LCC in the Global satellite data). However, whereas it cannot be claimed that cloud cover observed at Lomnicky stit (LSCC) can be used directly as a proxy for the Global LCC, its examination has value because it is an independent estimate of cloud cover and one that has a different altitude weighting to that adopted in the satellite-derived LCC. This statement is derived from satellite data (http://isccp.giss.nasa.gov/climanal7.html) which shows the time series for the period 1983–2010 for 9 cloud regimes. There is a significant correlation only between cosmic ray (CR) intensity (and sunspot number (SSN)) and the cloud cover of the types cirrus and stratus. This effect is mainly confined to the CR intensity minimum during the epoch around 1990, when the SSN was at its maximum. This fact, together with the present study of the correlation of LSCC with our measured CR intensity, shows that there is no firm evidence for a significant contribution of CR induced ionization to the local (or, indeed, Global) cloud cover. Pressure effects are the preferred cause of the cloud cover changes. A consequence is that there is no evidence favouring a contribution of CR to the Global Warming problem. Our analysis shows that the LS data are consistent with the Gas Laws for a stable mass of atmosphere.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.08.002
      Issue No: Vol. 148 (2016)
       
  • foF2 vs solar indices for the Rome station: Looking for the best general
           relation which is able to describe the anomalous minimum between cycles 23
           and 24
    • Authors: L. Perna; M. Pezzopane
      Pages: 13 - 21
      Abstract: Publication date: October 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 148
      Author(s): L. Perna, M. Pezzopane
      Analyses of the dependence of the F2layer critical frequency, foF2, on five widely used solar activity indices (F 10.7, Lym-α, MgII, R and EUV 0.1–50)are carried out considering noon values manually validated at the ionospheric station of Rome (41.8°N, 12.5°E, Italy) between January 1976 and December 2013, a period of time covering the last three solar cycles and including the prolonged and anomalous minimum of solar cycle 23/24 (years 2008–2009). After applying a 1-year running mean to both foF2 and solar activity indices time series, a second order polynomial fitting proves to perform better than a linear one, and this is specifically due to the very low solar activity of the last solar minimum and to the remaining saturation effect characterizing the high solar activity. A comparison between observed and synthetic foF2 values, the latter calculated by using the analytical relations found for every index, and some considerations made on the R parameter introduced by Solomon et al. (2013), suggest that MgII is the best index to describe the dependence of foF2 on the solar activity. Three main reasons justify this result: (1) the good sensibility of MgII to the variations of foF2 for low solar activity; (2) the reduced saturation effect characterizing MgII at high solar activity; (3) the poor influence of the hysteresis effect characterizing MgII at medium solar activity. On the other hand, the F 10.7 index, widely used as input parameter for numerous ionospheric models, does not represent properly the last minimum; specifically, it is not able to describe the variations of foF2 under a solar activity level of F 10.7=82·10–22 [JHz–1 s–1 m–2].

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.08.003
      Issue No: Vol. 148 (2016)
       
  • Scattering of relativistic and ultra-relativistic electrons by obliquely
           propagating Electromagnetic Ion Cyclotron waves
    • Authors: Bogdan Uzbekov; Yuri Y. Shprits; Ksenia Orlova
      Pages: 22 - 31
      Abstract: Publication date: October 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 148
      Author(s): Bogdan Uzbekov, Yuri Y. Shprits, Ksenia Orlova
      Electromagnetic Ion Cyclotron (EMIC) waves are transverse plasma waves that are generated in the Earth magnetosphere by ring current protons with temperature anisotropy in three different bands: below the H + , He + and O + ion gyrofrequencies. EMIC events are enhanced during the main phase of a geomagnetic storm when intensifications in the electric field result in enhanced injections of ions and are usually confined to high-density regions just inside the plasmapause or within drainage plumes. EMIC waves are capable of scattering radiation belt electrons and thus provide an important link between the intensification of the electric field, ion populations, and radiation belt electrons. Bounce-averaged diffusion coefficients computed with the assumption of parallel wave propagation are compared to the results of the code that uses the full cold plasma dispersion relation taking into account oblique propagation of waves and higher-order resonances. We study the sensitivity of the scattering rates to a number of included higher-order resonances, wave spectral distribution parameters, wave normal angle distribution parameters, ambient plasma density, and ion composition. Inaccuracies associated with the neglect of higher-order resonances and oblique propagation of waves are compared to potential errors introduced by uncertainties in the model input parameters.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.08.004
      Issue No: Vol. 148 (2016)
       
  • Fluorescence caused by ionizing radiation from ball lightning: Observation
           and quantitative analysis
    • Authors: Karl D. Stephan; Rozlyn Krajcik; Rolf J. Martin
      Pages: 32 - 38
      Abstract: Publication date: October 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 148
      Author(s): Karl D. Stephan, Rozlyn Krajcik, Rolf J. Martin
      Ball lightning is a rare phenomenon, typically appearing as a glowing sphere associated with thunderstorms. In 2008 one of the authors witnessed a blue ball-lightning object hover in front of a glass window that appeared to glow yellow. Calibrated quantitative fluorometry measurements of the window show that the glow was probably due to fluorescence caused by ionizing radiation (UV or possibly X rays). Based on the measurements performed, estimates of the total ionizing-radiation power emitted by the object range upward from about 10W. These are among the most reliable semi-quantitative measurements so far of ionizing-radiation output from a ball-lightning object.
      Graphical abstract image

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.08.005
      Issue No: Vol. 148 (2016)
       
  • High-Resolution Observations and Modeling of Turbulence Sources,
           Structures, and Intensities in the Upper Mesosphere
    • Authors: David C. Fritts; Ling Wang; Gerd Baumgarten; Amber D. Miller; Marvin A. Geller; Glenn Jones; Michele Limon; Daniel Chapman; Joy Didier; Carl B. Kjellstrand; Derek Araujo; Seth Hillbrand; Andrei Korotkov; Gregory Tucker; Jerry Vinokurov
      Abstract: Publication date: Available online 24 November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): David C. Fritts, Ling Wang, Gerd Baumgarten, Amber D. Miller, Marvin A. Geller, Glenn Jones, Michele Limon, Daniel Chapman, Joy Didier, Carl B. Kjellstrand, Derek Araujo, Seth Hillbrand, Andrei Korotkov, Gregory Tucker, Jerry Vinokurov
      New capabilities for imaging small-scale instabilities and turbulence and for modeling gravity wave (GW), instability, and turbulence dynamics at high Reynolds numbers are employed to identify the major instabilities and quantify turbulence intensities near the summer mesopause. High-resolution imaging of polar mesospheric clouds (PMCs) reveal a range of instability dynamics and turbulence sources that have their roots in multi-scale GW dynamics at larger spatial scales. Direct numerical simulations (DNS) of these dynamics exhibit a range of instability types that closely resemble instabilities and turbulence seen in PMC imaging and by ground-based and in-situ instruments at all times and altitudes. The DNS also exhibit the development of “sheet-and-layer” (S&L) structures in the horizontal wind and thermal stability fields that resemble observed flows near the mesopause and at lower altitudes. Both observations and modeling suggest major roles for GW breaking, Kelvin-Helmholtz instabilities (KHI), and intrusions in turbulence generation and energy dissipation. Of these, larger-scale GW breaking and KHI play the major roles in energetic flows leading to strong turbulence. GW propagation and breaking can span several S&L features and induce KHI ranging from GW to turbulence scales. Intrusions make comparable contributions to turbulence generation as instabilities become weaker and more intermittent. Turbulence intensities are highly variable in the vertical and typically span 3 or more decades. DNS results that closely resemble observed flows suggest a range of mechanical energy dissipation rates of ε ~10-3-10 Wkg-1 that is consistent with the range of in-situ measurements at ~80–90km in summer.

      PubDate: 2016-11-30T09:27:24Z
      DOI: 10.1016/j.jastp.2016.11.006
       
  • IFC-Ed. board
    • Abstract: Publication date: October 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 148


      PubDate: 2016-11-23T06:38:05Z
       
  • Statistical characterization of high-to-medium frequency mesoscale gravity
           waves by lidar-measured vertical winds and temperatures in the MLT
    • Authors: Xian Lu; Xinzhao Chu; Haoyu Li; Cao Chen; John A. Smith; Sharon L. Vadas
      Abstract: Publication date: Available online 18 October 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Xian Lu, Xinzhao Chu, Haoyu Li, Cao Chen, John A. Smith, Sharon L. Vadas
      We present the first statistical study of gravity waves with periods of 0.3–2.5h that are persistent and dominant in the vertical winds measured with the University of Colorado STAR Na Doppler lidar in Boulder, CO (40.1°N, 105.2°W). The probability density functions of the wave amplitudes in temperature and vertical wind, ratios of these two amplitudes, phase differences between them, and vertical wavelengths are derived directly from the observations. The intrinsic period and horizontal wavelength of each wave are inferred from its vertical wavelength, amplitude ratio, and a designated eddy viscosity by applying the gravity wave polarization and dispersion relations. The amplitude ratios are positively correlated with the ground-based periods with a coefficient of ~0.76. The phase differences between the vertical winds and temperatures ( φ W − φ T ) follow a Gaussian distribution with 84.2±26.7°, which has a much larger standard deviation than that predicted for non-dissipative waves (~3.3°). The deviations of the observed phase differences from their predicted values for non-dissipative waves may indicate wave dissipation. The shorter-vertical-wavelength waves tend to have larger phase difference deviations, implying that the dissipative effects are more significant for shorter waves. The majority of these waves have the vertical wavelengths ranging from 5 to 40km with a mean and standard deviation of ~18.6 and 7.2km, respectively. For waves with similar periods, multiple peaks in the vertical wavelengths are identified frequently and the ones peaking in the vertical wind are statistically longer than those peaking in the temperature. The horizontal wavelengths range mostly from 50 to 500km with a mean and median of ~180 and 125km, respectively. Therefore, these waves are mesoscale waves with high-to-medium frequencies. Since they have recently become resolvable in high-resolution general circulation models (GCMs), this statistical study provides an important and timely reference for them.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.009
       
  • Two-dimensional Morlet wavelet transform and its application to wave
           recognition methodology of automatically extracting two-dimensional wave
           packets from lidar observations in Antarctica
    • Authors: Cao Chen; Xinzhao Chu
      Abstract: Publication date: Available online 27 October 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Cao Chen, Xinzhao Chu
      Waves in the atmosphere and ocean are inherently intermittent, with amplitudes, frequencies, or wavelengths varying in time and space. Most waves exhibit wave packet-like properties, propagate at oblique angles, and are often observed in two-dimensional (2-D) datasets. These features make the wavelet transforms, especially the 2-D wavelet approach, more appealing than the traditional windowed Fourier analysis, because the former allows adaptive time-frequency window width (i.e., automatically narrowing window size at high frequencies and widening at low frequencies), while the latter uses a fixed envelope function. This study establishes the mathematical formalism of modified 1-D and 2-D Morlet wavelet transforms, ensuring that the power of the wavelet transform in the frequency/wavenumber domain is equivalent to the mean power of its counterpart in the time/space domain. Consequently, the modified wavelet transforms eliminate the bias against high-frequency/small-scale waves in the conventional wavelet methods and many existing codes. Based on the modified 2-D Morlet wavelet transform, we put forward a wave recognition methodology that automatically identifies and extracts 2-D quasi-monochromatic wave packets and then derives their wave properties including wave periods, wavelengths, phase speeds, and time/space spans. A step-by-step demonstration of this methodology is given on analyzing the lidar data taken during 28–30 June 2014 at McMurdo, Antarctica. The newly developed wave recognition methodology is then applied to two more lidar observations in May and July 2014, to analyze the recently discovered persistent gravity waves in Antarctica. The decomposed inertia-gravity wave characteristics are consistent with the conclusion in Chen et al. (2016a) that the 3–10h waves are persistent and dominant, and exhibit lifetimes of multiple days. They have vertical wavelengths of 20–30km, vertical phase speeds of 0.5–2m/s, and horizontal wavelengths up to several thousands kilometers in the mesosphere and lower thermosphere (MLT). The variations in the extracted wave properties from different months in winter indicate a month-to-month variability in the gravity wave activities in the Antarctic MLT region.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.10.016
       
  • Atmospheric ionization induced by precipitating electrons: Comparison of
           CRAC:EPII model with a parametrization model
    • Authors: A.A. Artamonov; A.L. Mishev I.G. Usoskin
      Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149
      Author(s): A.A. Artamonov, A.L. Mishev, I.G. Usoskin
      Results of a comparison of a new model CRAC:EPII (Cosmic Ray Atmospheric Cascade: Electron Precipitation Induced Ionization) with a commonly used parametric model of atmospheric ionization is presented. The CRAC:EPII is based on a Monte Carlo simulation of precipitating electrons propagation and interaction with matter in the Earth's atmosphere. It explicitly considers energy deposit: ionization, pair production, Compton scattering, generation of Bremsstrahlung high energy photons, photo-ionization and annihilation of positrons, multiple scattering as physical processes accordingly. Propagation of precipitating electrons and their interactions with air is simulated with the GEANT4 simulation tool PLANETOCOSMICS code using NRLMSISE-00 atmospheric model. Ionization yields are computed and compared with a parametrization model for different energies of incident precipitating energetic electrons, using simulated fluxes of mono-energetic particles. A good agreement between the two models is achieved in the mesosphere but the contribution of Bremsstrahlung in the stratosphere, which is not accounted for in the parametric models, is found significant. As an example, we calculated profiles of the ion production rates in the middle and upper atmosphere (below 100km) on the basis of balloon-born measured spectra of precipitating electrons for 30-October-2002 and 07-January-2004.

      PubDate: 2016-11-23T06:38:05Z
       
  • IFC-Ed. board
    • Abstract: Publication date: November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 149


      PubDate: 2016-11-23T06:38:05Z
       
  • Spatiotemporal assessment of CO2 emissions and its satellite remote
           sensing over Pakistan and neighboring regions
    • Authors: Zia ul-Haq; Salman Tariq; Muhammad Ali
      Abstract: Publication date: Available online 9 November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Zia ul-Haq, Salman Tariq, Muhammad Ali
      For the first time, anthropogenic CO2 emissions and spatiotemporal variability of mid-tropospheric CO2 has been discussed using EDGAR database and Atmospheric Infrared Sounder (AIRS) onboard Aqua satellite observations. The EDGAR data indicate an increase of 147% in anthropogenic CO2 emissions from 66101 to 163737 Gg for Pakistan during the period of 1990−2008. Dera Ghazi Khan (Pakistan) is found with the highest increase of 260% of anthropogenic CO2 emissions followed by Delhi (India) 153%, Karachi (Pakistan) 66% and Lahore (Pakistan) 59% whereas a decreasing trend of −53% is observed for Kabul (Afghanistan) during 1990−2008. Industrial activities, road transportation, open field crop-waste burning, and energy production have been identified as major anthropogenic emission sources of CO2 in the studied region. AIRS CO2 retrievals over Pakistan and adjoining areas of India and Afghanistan show an averaged CO2 to be 383±5 ppm with a positive trend of 5.05% during December 2002 to February 2012. An elevated value of CO2 has been observed over northern mountainous and high human settlement regions. The seasonal analysis shows a spring maximum 385±5 ppm with a secondary peak in late autumn, and the highest increasing trend of 5.5% associated with winter. May and August showed maximum and minimum mean monthly values of 385±5 ppm and 382±5 ppm respectively. HYSPLIT trajectories of air masses movement have been drawn to track CO2 transport.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.11.001
       
  • Sensitivity of equatorial atomic oxygen in the MLT region to the 11-year
           and 27-day solar cycles
    • Authors: Olexandr Lednyts'kyy; Christian von Savigny; Mark Weber
      Abstract: Publication date: Available online 19 November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Olexandr Lednyts'kyy, Christian von Savigny, Mark Weber
      We report on 27-day and 11-year solar cycle signatures in atomic oxygen (O) concentrations ([O]) in the MLT (Mesosphere/Lower Thermosphere) region of the terrestrial atmosphere. MLT [O] profiles were retrieved on the base of green line (557.7nm) nightglow data sets provided by the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard Envisat from 2002 to 2012. A statistically significant solar 27-day signature was identified (and then quantified with respect to the sensitivity and phase relationship to solar forcing) in time series of MLT [O] profiles with use of cross-correlation and superposed epoch analysis techniques. It was the first identification of the solar 27-day signature in MLT atomic oxygen on the base of such experimental data sets. The sensitivity of [O] to solar cycle variability at the 11-year time scale was quantified with use of cross-correlation and multiple-linear regression analysis techniques, which yield results consistent with known studies and, particularly, indicate that the sensitivity of [O] to solar forcing increases with increasing altitude. A comparison of obtained values of atomic oxygen sensitivity in response to solar forcing at the 27-day and 11-year time scales reveals the fact that the sensitivities agree well to each other within their uncertainties during the descending phase of the last (23rd) 11-year cycle of solar activity, whereas the [O] sensitivity values at the 27-day time scale during the last solar minimum phase were lower than those ones during the descending phase. It was also determined that atomic oxygen is in-phase with the solar forcing (in agreement with model results) at the 11-year time scale, whereas the time lag of the 27-day signature in response to solar forcing was about 12 – 14 days.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.11.003
       
  • Seasonal, inter-annual and solar cycle variability of the quasi two day
           wave in the low-latitude mesosphere and lower thermosphere
    • Authors: N. Venkateswara Rao; M. Venkat Ratnam; C. Vedavathi; T. Tsuda; B.V. Krishna Murthy; S. Sathishkumar; S. Gurubaran; K. Kishore Kumar; K.V. Subrahmanyam; S. Vijaya Bhaskara Rao
      Abstract: Publication date: Available online 22 November 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): N. Venkateswara Rao, M. Venkat Ratnam, C. Vedavathi, T. Tsuda, B.V. Krishna Murthy, S. Sathishkumar, S. Gurubaran, K. Kishore Kumar, K.V. Subrahmanyam, S. Vijaya Bhaskara Rao
      We analyzed 17 years (1993–2009) of horizontal winds measured by the medium frequency (MF) radar located at Tirunelveli (8.7°N, 77.8°E) and 10 years (2005–2014) of horizontal winds measured by a meteor radar located at Thumba (8.5°N, 77°E) to examine the seasonal, inter-annual, and solar cycle variability of the Quasi-Two Day Wave (QTDW) in the mesosphere and lower thermosphere region. These two radars are nearly co-located, but differ in their measurement technique. Comparison of the estimated QTDW amplitudes by the two radars shows that the amplitudes are larger in the meteor radar than those in the MF radar. The difference between the amplitudes is larger in May in the zonal component and in April and September in the meridional one. Furthermore, the differences are larger in the meridional component. The QTDWs in both the radars show a strong semi-annual oscillation (SAO). In addition, the meridional QTDW amplitudes of both the MF and meteor radars show a distinct enhancement in the month of October. While the whole spectra of QTDWs contribute to the SAO amplitudes, only 45–50 h waves contribute to the October enhancement. The amplitudes of the QTDWs, in general, show large inter-annual variability. The QTDW amplitudes from both the radars show modulation at period of quasi-biennial oscillation. The QTDWs of the MF radar show a small negative correlation with solar activity while those of meteor radar do not show any correlation. The above aspects are discussed in the light of current understanding of the QTDWs.

      PubDate: 2016-11-23T06:38:05Z
      DOI: 10.1016/j.jastp.2016.11.005
       
  • IFC-Ed. board
    • Abstract: Publication date: December 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 150–151


      PubDate: 2016-11-23T06:38:05Z
       
 
 
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