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  Subjects -> METEOROLOGY (Total: 89 journals)
Showing 1 - 36 of 36 Journals sorted alphabetically
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 34)
Advances in Climate Change Research     Open Access   (Followers: 10)
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: 15)
American Journal of Climate Change     Open Access   (Followers: 15)
Atmósfera     Open Access   (Followers: 2)
Atmosphere     Open Access   (Followers: 21)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 12)
Atmospheric and Oceanic Science Letters     Open Access   (Followers: 2)
Atmospheric Chemistry and Physics (ACP)     Open Access   (Followers: 31)
Atmospheric Chemistry and Physics Discussions (ACPD)     Open Access   (Followers: 11)
Atmospheric Research     Hybrid Journal   (Followers: 56)
Atmospheric Science Letters     Open Access   (Followers: 29)
Boundary-Layer Meteorology     Hybrid Journal   (Followers: 23)
Bulletin of the American Meteorological Society     Open Access   (Followers: 33)
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: 12)
Climate Change Responses     Open Access   (Followers: 4)
Climate Dynamics     Hybrid Journal   (Followers: 30)
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: 29)
Climate Research     Hybrid Journal   (Followers: 5)
Climate Risk Management     Open Access   (Followers: 1)
Climate Services     Open Access  
Climate Summary of South Africa     Full-text available via subscription  
Climatic Change     Hybrid Journal   (Followers: 55)
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: 3)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 11)
Earth Perspectives - Transdisciplinarity Enabled     Open Access  
Energy & Environment     Hybrid Journal   (Followers: 18)
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: 14)
International Journal of Climatology     Hybrid Journal   (Followers: 25)
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: 130)
Journal of Atmospheric Chemistry     Hybrid Journal   (Followers: 21)
Journal of Climate     Full-text available via subscription   (Followers: 40)
Journal of Hydrology and Meteorology     Open Access   (Followers: 14)
Journal of Hydrometeorology     Full-text available via subscription   (Followers: 6)
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: 21)
Journal of the Atmospheric Sciences     Full-text available via subscription   (Followers: 69)
Journal of the Meteorological Society of Japan     Partially Free   (Followers: 3)
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: 10)
Monthly Weather Review     Full-text available via subscription   (Followers: 26)
Nature Climate Change     Full-text available via subscription   (Followers: 66)
Nature Reports Climate Change     Full-text available via subscription   (Followers: 27)
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: 17)
Studia Geophysica et Geodaetica     Hybrid Journal   (Followers: 1)
Tellus A     Open Access   (Followers: 23)
Tellus B     Open Access   (Followers: 21)
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: 22)
Theoretical and Applied Climatology     Hybrid Journal   (Followers: 8)
Urban Climate     Hybrid Journal  
Weather     Hybrid Journal   (Followers: 14)
Weather and Climate Extremes     Open Access   (Followers: 8)
Weather and Forecasting     Full-text available via subscription   (Followers: 16)
Weatherwise     Hybrid Journal   (Followers: 2)
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]   [130 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1364-6826
   Published by Elsevier Homepage  [3042 journals]
  • Generalized models for estimation of diffuse solar radiation based on
           clearness index and sunshine duration in India: Applicability under
           different climatic zones
    • Authors: Basharat Jamil; Abid T. Siddiqui
      Pages: 16 - 34
      Abstract: Publication date: May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 157–158
      Author(s): Basharat Jamil, Abid T. Siddiqui
      Generalized models for assessment of monthly average diffuse solar radiation over India were established using long-term solar radiation data available for 15 years (1986–2000) obtained from Indian Meteorological Department (IMD), Pune. Regression analysis was employed to correlate the diffuse fraction ( K ̅ d ) with clearness index ( K ̅ t ) and relative sunshine period v ( S ̅ S ̅ o ) together. Seven new models (with two input variables i.e. global solar radiation and relative sunshine period) were developed using data of the measurement sites. Well-established models from literature were also compared with the proposed models. Statistical tests used to evaluate the accuracy of models were mean bias error, root mean square error, mean percentage error, coefficient of determination, t-statistics and normalized median absolute deviation. Global performance indicator (GPI) was used to rank the models. Further, the empirical models were applied on the five representative locations under diverse climatic zones (i.e. Hot & Dry, Warm & Humid, Temperate, Cold and Composite climates) prescribed by the Energy Conservation Building Code (ECBC) for India. Proposed models were also compared within each climatic zone and best model was recommended. Developed models were found to have good performance on collective data as well as under each climatic zone individually.

      PubDate: 2017-04-03T16:22:02Z
      DOI: 10.1016/j.jastp.2017.03.013
      Issue No: Vol. 157-158 (2017)
       
  • Unexpected East-West effect in mesopause region SABER temperatures over El
           Leoncito
    • Authors: Esteban R. Reisin; Jürgen Scheer
      Pages: 35 - 41
      Abstract: Publication date: Available online 31 March 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Esteban R. Reisin, Jürgen Scheer
      We find that mesopause region temperatures determined by the SABER instrument on the TIMED satellite during nocturnal overpasses at El Leoncito (31.8°S, 69.3°W) are several kelvins higher when SABER observes from the East than when it observes from the West. We distinguish between altitudes corresponding to the nominal emission heights of the OH and O2 airglow layers. The East-West temperature differences of 4.5K obtained for OH-equivalent height, and of 3.5K for O2-equivalent height are surprising, because an effect of the South Atlantic Anomaly on SABER temperature is unexpected. However, the ground-based data obtained with our airglow spectrometer at El Leoncito show that such a SABER artifact can be ruled out. Rather, the phenomenon is explained as a consequence of the temporal sampling of the nocturnal variation, which is mostly due to the semidiurnal tide. The monthly mean tide is strongest from April to September with a mean amplitude of 6.9K for OH, and of 10.5K for O2 rotational temperature, but the contribution to the East-West effect varies strongly from month to month because of differences in the temporal sampling. This mechanism should be active at other sites, as well.

      PubDate: 2017-04-03T16:22:02Z
      DOI: 10.1016/j.jastp.2017.03.016
      Issue No: Vol. 157-158 (2017)
       
  • Comparison of quiet time vertical plasma drifts with global empirical
           models over the Indian sector: Some insights
    • Authors: Kuldeep Pandey; R. Sekar; S.P. Gupta; D. Chakrabarty; B.G. Anandarao
      Pages: 42 - 54
      Abstract: Publication date: Available online 28 March 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Kuldeep Pandey, R. Sekar, S.P. Gupta, D. Chakrabarty, B.G. Anandarao
      The threshold vertical plasma drifts and their polarities are inferred from E-region irregularities reported earlier using different experiments conducted from India during geomagnetically quiet time. In addition, the hourly variations of magnetometer data sets are used in conjunction with an equatorial electrojet model (Anandarao, 1976) to deduce the vertical drifts around noon time (10:00–140:0 LT). These results are then compared with the vertical drifts presented by empirical models (Scherliess and Fejer, 1999; Fejer et al., 2008a) corresponding to the 60 ° E longitude sector. In general, the vertical drifts presented by empirical models are consistent with those inferred from snapshot measurements of E-region irregularities at different local times of the day except around sunrise hours. Further, the vertical drifts presented by Fejer et al. (2008a) model match fairly well with seasonally averaged vertical drifts deduced (within 1 σ variation) using magnetometer data. A time difference is noticed between occurrence of pre-reversal enhancement in vertical drifts over India reported earlier using different techniques and Scherliess and Fejer (1999) model. Probable reason for the time difference is discussed. The occurrence characteristic of afternoon equatorial counter electrojet in June solstice during low solar epoch is consistent with the drifts obtained from empirical models. The seasonally averaged vertical drifts during nighttime reported earlier using ionosonde/HF radar experiments are not consistent with the presence of streaming plasma waves on a few occasions. Further, nocturnal vertical drifts are systematically under-estimated and probable reason for this is discussed.

      PubDate: 2017-04-03T16:22:02Z
      DOI: 10.1016/j.jastp.2017.03.012
      Issue No: Vol. 157-158 (2017)
       
  • Temporal variation of Black Carbon concentration using Aethalometer
           observations and its relationships with meteorological variables in
           Karachi, Pakistan
    • Authors: Samina Bibi; Khan Alam; Farrukh Chishtie; Humera Bibi; Said Rahman
      Pages: 67 - 77
      Abstract: Publication date: May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 157–158
      Author(s): Samina Bibi, Khan Alam, Farrukh Chishtie, Humera Bibi, Said Rahman
      Black Carbon (BC) mass concentration was measured continuously for every five-minute interval with ground-based Aethalometer at an urban site in Karachi for the period from 2006 to 2008. In this study, the temporal (diurnal, monthly and seasonal) variations of BC and its relationship with meteorological variables were analyzed. Monthly averaged concentrations of BC ranged from 2.2 to 12.5µg/m3, with maximum in the month of January 2007 and minimum in the month of June 2006. BC showed higher concentrations during the months of January, February and November while lower during the months of May, June, July and August throughout the years. It also displayed comparatively high concentrations during winter and postmonsoon, while moderate during premonsoon and low during summer. Diurnal analysis of BC concentration showed sharp peaks between 07:00 and 09:00 LST and again around 22:00 during all the months. Moreover, the relationship between BC concentration and meteorological variables such as Temperature (Temp), Relative Humidity (RH), Wind Speed (WS), Visibility (VIS) and RainFall (RF) was found and it was observed that BC concentration showed an inverse relationship with all these meteorological variables. Finally, the analysis of the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) cluster trajectories revealed that almost all the clusters were originating from southwest of the study site.

      PubDate: 2017-04-11T16:52:25Z
      DOI: 10.1016/j.jastp.2017.03.017
      Issue No: Vol. 157-158 (2017)
       
  • Observed effects in the equatorial and low-latitude ionosphere in the
           South American and African sectors during the 2012 minor sudden
           stratospheric warming
    • Authors: R. de Jesus; I.S. Batista; A.J. de Abreu; P.R. Fagundes; K. Venkatesh; C.M. Denardini
      Pages: 78 - 89
      Abstract: Publication date: May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 157–158
      Author(s): R. de Jesus, I.S. Batista, A.J. de Abreu, P.R. Fagundes, K. Venkatesh, C.M. Denardini
      In this paper, the effects of a minor sudden stratospheric warming (SSW) event of 2012 in the ionosphere over South American and African sectors have been studied using C/NOFS satellite data and GPS observations. Also, the magnetometer measurements obtained at two stations in the equatorial and low-latitude regions in the South American sector are presented. There were significant Vertical Total Electron Content (VTEC) depletions in the afternoon in both South American and African sectors during the 2012 minor SSW event. A novel feature of the present study is the reduction of the quasi 16-day oscillation (periods ranging from 11 to 20 days) in the daily averaged VTEC in the Brazilian and African sector during an SSW event. Also, the results for the Brazilian sector show an amplification of the ~2–6day period in the daily averaged VTEC at equatorial and low-latitude regions, after the SSW temperature peak. This investigation shows that a minor SSW can affect the irregularities at ionospheric heights in the Brazilian and African sectors. Ground-based magnetometer measurements in the American sector shows strongly enhanced equatorial electrojet (EEJ) after the SSW temperature peak.

      PubDate: 2017-04-11T16:52:25Z
      DOI: 10.1016/j.jastp.2017.04.003
      Issue No: Vol. 157-158 (2017)
       
  • IFC-Ed. board
    • Abstract: Publication date: July 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 160


      PubDate: 2017-06-21T16:19:21Z
       
  • IFC-Ed. board
    • Abstract: Publication date: June 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 159


      PubDate: 2017-06-16T16:12:40Z
       
  • Coronal flux ropes and their interplanetary counterparts
    • Authors: N. Gopalswamy; S. Akiyama; S. Yashiro; H. Xie
      Abstract: Publication date: Available online 9 June 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): N. Gopalswamy, S. Akiyama, S. Yashiro, H. Xie
      We report on a study comparing coronal flux ropes inferred from eruption data with their interplanetary counterparts constructed from in situ data. The eruption data include the source-region magnetic field, post-eruption arcades, and coronal mass ejections (CMEs). Flux ropes were fit to the interplanetary CMEs (ICMEs) considered for the 2011 and 2012 Coordinated Data Analysis Workshops (CDAWs). We computed the total reconnected flux involved in each of the associated solar eruptions and found it to be closely related to flare properties, CME kinematics, and ICME properties. By fitting flux ropes to the white-light coronagraph data, we obtained the geometric properties of the flux ropes and added magnetic properties derived from the reconnected flux. We found that the CME magnetic field in the corona is significantly higher than the ambient magnetic field at a given heliocentric distance. The radial dependence of the flux-rope magnetic field strength is faster than that of the ambient magnetic field. The magnetic field strength of the coronal flux rope is also correlated with that in interplanetary flux ropes constructed from in situ data, and with the observed peak magnetic field strength in ICMEs. The physical reason for the observed correlation between the peak field strength in MCs is the higher magnetic field content in faster coronal flux ropes and ultimately the higher reconnected flux in the eruption region. The magnetic flux ropes constructed from the eruption data and coronagraph observations provide a realistic input that can be used by various models to predict the magnetic properties of ICMEs at Earth and other destination in the heliosphere.

      PubDate: 2017-06-11T16:00:27Z
      DOI: 10.1016/j.jastp.2017.06.004
       
  • Determination of effective droplet radius and optical depth of liquid
           water clouds over a tropical site in northern Thailand using passive
           microwave soundings, aircraft measurements and spectral irradiance data
    • Authors: P. Nimnuan; S. Janjai; M. Nunez; N. Pratummasoot; S. Buntoung; D. Charuchittipan; T. Chanyatham; P. Chantraket; N. Tantiplubthong
      Abstract: Publication date: Available online 6 June 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): P. Nimnuan, S. Janjai, M. Nunez, N. Pratummasoot, S. Buntoung, D. Charuchittipan, T. Chanyatham, P. Chantraket, N. Tantiplubthong
      This paper presents an algorithm for deriving the effective droplet radius and optical depth of liquid water clouds using ground-based measurements, aircraft observations and an adiabatic model of cloud liquid water. The algorithm derives cloud effective radius and cloud optical depth over a tropical site at Omkoi (17.80°N, 98.43°E), Thailand. Monthly averages of cloud optical depth are highest in April (54.5), which is the month with the lowest average cloud effective radius (4.2 μm), both occurring before the start of the rainy season and at the end of the high contamination period. By contrast, the monsoon period extending from May to October brings higher cloud effective radius and lower cloud optical depth to the region on average. At the diurnal scale there is a gradual increase in average cloud optical depth and decrease in cloud effective radius as the day progresses.

      PubDate: 2017-06-11T16:00:27Z
      DOI: 10.1016/j.jastp.2017.06.002
       
  • Signature of the quasi-27-day oscillation in the MLT and its relation with
           solar irradiance and convection
    • Authors: A. Guharay; P.P. Batista; R.A. Buriti; N.J. Schuch
      Abstract: Publication date: Available online 3 June 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): A. Guharay, P.P. Batista, R.A. Buriti, N.J. Schuch
      Intermittent occurrence of the quasi-27-day oscillation is observed in the mesosphere and lower thermosphere (MLT) zonal wind in the long term database over three southern hemispheric Brazilian locations, i.e. Sao Joao do Cariri (7.4°S, 36.5°W), Cachoeira Paulista (22.7°S, 45°W) and Santa Maria (29.7°S, 53.7°W). The oscillation shows a peak amplitude of ∼15 m/s in the lower MLT. To determine the plausible sources of the quasi-27-day oscillation, the variation of the solar Ly-α flux and outgoing longwave radiation (proxy for convection) have been looked into. The oscillation shows considerable consistency with the solar UV flux implying potential solar influence on excitation. The oscillation in the MLT also exhibits good correlation with the outgoing longwave radiation (a proxy of convection) at Cachoeira Paulista indicating plausible influence of lower atmospheric convective activity. Non-concurrent occurrence of the oscillation among the observational stations indicates potential role of local geophysical conditions. The zonal background wind in the MLT might cause dissipation of the upward propagating waves (modulated by 27-day oscillation) and hence imprint the lower atmospheric 27-day signature in the MLT.

      PubDate: 2017-06-06T15:10:54Z
      DOI: 10.1016/j.jastp.2017.06.001
       
  • Spectral characteristics of ionospheric scintillations of UHF radiosignal
           near magnetic zenith
    • Authors: Roman Vasilyev; Maria Globa Dmitry Kushnarev Andrey Medvedev Konstantin Ratovsky
      Abstract: Publication date: Available online 30 May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Roman Vasilyev, Maria Globa, Dmitry Kushnarev, Andrey Medvedev, Konstantin Ratovsky
      We present the results of observing the Cygnus-A radio source scintillation in the Earth's ionosphere under quiet and disturbed geomagnetic conditions by using the Irkutsk incoherent scattering radar (IISR). The scintillation method applied for ionosphere testing at IISR confidently determines the Fresnel frequency and power cutoff, the spectral characteristics usually related to the velocities and spatial spectra of ionospheric plasma irregularities. We also use the IGFR magnetic field model to show the relation between the shape of discrete radio source scintillation spectra and the direction to the radio source with respect to the geomagnetic field. The S4 index increase within the magnetic zenith is observed to be conditioned by the scintillation spectrum widening. We also evaluate the zonal velocity of observed ionospheric irregularities as ∼10 m/sec assuming the irregularity height to be equal to the F2-layer maximum height in the ionosphere.

      PubDate: 2017-06-02T14:40:25Z
       
  • Radar observations of the quarterdiurnal tide at midlatitudes: Seasonal
           and long-term variations
    • Authors: Christoph Jacobi; Amelie Krug; Eugeny Merzlyakov
      Abstract: Publication date: Available online 30 May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Christoph Jacobi, Amelie Krug, Eugeny Merzlyakov
      The seasonal and interannual variability of the quarterdiurnal tide is analysed using meteor radar wind observations at the two midlatitude sites Collm and Obninsk. Generally tidal amplitudes increase with height. Maximum tidal amplitudes are found in winter. Meridional amplitudes are smaller than zonal ones on an average. Phases mainly differ between summer and winter. Zonal and meridional phases differ by slightly less than 90°. The vertical wavelengths are very long in winter, but shorter and on the order of 20 km in summer. Collm and Obninsk amplitudes and phases agree well, indicating that the migrating quarterdiurnal tide may be responsible for a major part of the observed waves. Observations since 1980 show that the tidal amplitudes have increased on a whole, although the increase is not linear but mainly happening during the late 1990s and the early 2000s.

      PubDate: 2017-06-02T14:40:25Z
      DOI: 10.1016/j.jastp.2017.05.014
       
  • Long term variabilities and tendencies of mesospheric lunar semidiurnal
           tide over Tirunelveli (8.7°N, 77.8°E)
    • Authors: S. Sathishkumar; S. Sridharan; P.V. Muhammed Kutty; S. Gurubaran
      Abstract: Publication date: Available online 29 May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): S. Sathishkumar, S. Sridharan, P.V. Muhammed Kutty, S. Gurubaran
      The medium frequency radar deployed at Tirunelveli (8.7°N, 77.8°E), which is located near the southmost tip of peninsular India, have been providing continuous data from the year 1993 to the year 2012 that helped to study the long term tendencies in the lunar tidal variabilities over this geographic location. In the present paper we present the results of seasonal, interannual and long-term variabilities of lunar semi-diurnal tides in the upper mesosphere over Tirunelveli. The present study also includes comparison with model values. The study shows that the tidal amplitudes are larger in the meridional components of the mesospheric winds than the zonal winds. The seasonal variations of the tides are similar in both the components. The tides show maximum amplitudes of about ∼5 m/s in February/March, secondary maximum amplitudes of about ∼3 m/s in September and minimum amplitudes during summer months (May–August). The observed seasonal variation of the lunar tides do not compare well with Vial and Forbes (1994) model values, though it is consistent with earlier observations. The lunar tidal phase in meridional winds leads that in zonal winds from January to June and from September to November, while the latter leads the former during July/August. The lunar tides show large interannual variability. There are unusual amplitude enhancements in the lunar tide in meridional winds during the winters of 2006 and 2009, when major sudden stratospheric warmings (SSW) occurred at high latitude northern hemisphere, whereas zonal lunar tide does not show any clear association with the SSW. Vertical wavelengths of lunar tides in zonal and meridional wind are in the range of 20–90 km. The vertical wavelengths of lunar tides in both zonal and meridional component are smaller in June and larger in November and December. The monthly mean zonal and meridional winds are subjected to regression analysis to study the tidal response to long-period oscillations, namely, quasi-biennial oscillation (QBO), solar cycle variation and El-nino southern oscillation (ENSO). It is found the lunar tide in both zonal and meridional winds show significant QBO response, whereas zonal tide only shows significant negative response to solar cycle and positive response to ENSO. Besides, zonal tide only shows significant long-term increasing trend.

      PubDate: 2017-06-02T14:40:25Z
      DOI: 10.1016/j.jastp.2017.05.015
       
  • Variability of virtual layered phenomena in the mesosphere observed with
           medium frequency radars at 69°N
    • Authors: Toralf Renkwitz; Ralph Latteck
      Abstract: Publication date: Available online 22 May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Toralf Renkwitz, Ralph Latteck
      The MF-Saura radar positioned at polar latitudes is very sensitive to enhanced ionization caused by solar and geomagnetic activity. Differing from the intensities normally detected by partial reflections from the ionospheric D region during quiet conditions, distinct layers can be seen due to intense increase of electron number density at as low as 50 km altitude caused by particle precipitation. Effects of energetic particle precipitation on observations by medium frequency (MF) radars have been rarely reported so far, generally associated with solar proton events, which are rather scarce especially during solar minimum conditions. Here, we focus on events associated with precipitation of particles with lower energy (<10 MeV), which are seen by the MF radar with occurrence rates of as much as 40% at times. Such situations are studied for a period of continuous observations for one solar cycle and statistical results like diurnal and annual distributions are presented.

      PubDate: 2017-05-23T04:28:22Z
      DOI: 10.1016/j.jastp.2017.05.009
       
  • Inferring geoeffective solar variability signature in stratospheric and
           tropospheric Northern Hemisphere temperatures
    • Authors: V. Dobrica; R. Pirloaga; C. Stefan; C. Demetrescu
      Abstract: Publication date: Available online 17 May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): V. Dobrica, R. Pirloaga, C. Stefan, C. Demetrescu
      Possible climatic effects related to geoeffective solar variability have been investigated by means of long-term statistical correlations between stratospheric and tropospheric temperature and solar/geomagnetic indices. Our previous work on solar variability signature in the long records of air temperature in Europe showed that there were significant solar signals at Schwabe (11 years) and Hale (22 years) solar cycles, with peak to trough amplitudes of several degrees, and, respectively, of 0.6–0.8 °C. In the present study we extend the investigation using NCEP/NCAR reanalyzed data for the temperate climate zone of the Northern Hemisphere (35-65ºN), from Earth's surface to stratospheric levels. Features of these signals are discussed on various spatial scales of the Northern Hemisphere and at specific levels in troposphere and stratosphere. The long-term statistical correlation between reanalyzed temperatures and indices describing solar variability (R, aa) is also investigated.

      PubDate: 2017-05-23T04:28:22Z
      DOI: 10.1016/j.jastp.2017.05.001
       
  • Evidence of MLT propagation of the plasmapause inferred from THEMIS data
    • Authors: Mario Bandić; Giuli Verbanac; Viviane Pierrard; Junghee Cho
      Abstract: Publication date: Available online 17 May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Mario Bandić, Giuli Verbanac, Viviane Pierrard, Junghee Cho
      The cross-correlation analysis is applied to the comprehensive database of THEMIS plasmapause crossings (6840 L PP s) and both solar wind parameters and geomagnetic indices (thereafter L PP indicators). We estimate MLTs of the plasmapause formation and further monitor the motion of the new plasmapause at high MLT resolution. Our results show that plasmapause is firstly formed within 23–07 MLT and then propagates around the Earth with the velocity estimated to amounts for 1.10 and 0.45 of the corotation velocity in sectors 07–15 MLT and 15–23 MLT, respectively. Two branches within 23–07 MLT are identified, one at low time lags (T lag s) and second at high T lag s which we relate to the formation of the new plasmapause and to the propagation of the plasmapause formed one MLT-cycle before. This study can be used to improve the current understanding of the plasmapause formation and propagation.

      PubDate: 2017-05-23T04:28:22Z
      DOI: 10.1016/j.jastp.2017.05.005
       
  • Solar energetic particle catalogs: Assumptions, uncertainties and validity
           of reports
    • Authors: R. Miteva; S.W. Samwel; M.V. Costa-Duarte
      Abstract: Publication date: Available online 16 May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): R. Miteva, S.W. Samwel, M.V. Costa-Duarte
      The aim of this work is to summarize the main underlying assumptions, simplifications and uncertainties while studying solar energetic particles (SEPs). In general, numerous definitions are used for the evaluation of a given SEP parameter and these different methods lead to different outcomes for a given particle event. Several catalogs of SEP events from various instruments are currently available; however, each catalog is specific to the adopted data and analysis. We investigate the differences while comparing several SEP catalogs and outline probable reasons. We focus on SEP statistical studies and quantify the influences of the particle intensity, solar origin location and projection effects. We found that different definitions and criteria used for these parameters change the values of the correlation coefficients between the SEPs and their solar origin.

      PubDate: 2017-05-23T04:28:22Z
      DOI: 10.1016/j.jastp.2017.05.003
       
  • Analysis of lightning-ionosphere interaction using simultaneous records of
           source current and 380-km distant electric field
    • Authors: Mohammad Azadifar; Dongshuai Li; Farhad Rachidi; Marcos Rubinstein; Gerhard Diendorfer; Wolfgang Schulz; Hannes Pichler; Vladimir A. Rakov; Mario Paolone; Davide Pavanello
      Abstract: Publication date: Available online 12 May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Mohammad Azadifar, Dongshuai Li, Farhad Rachidi, Marcos Rubinstein, Gerhard Diendorfer, Wolfgang Schulz, Hannes Pichler, Vladimir A. Rakov, Mario Paolone, Davide Pavanello
      We present simultaneous current and wideband electric field waveforms at 380 km associated with upward lightning flashes initiated from the Säntis Tower, Switzerland. To the best of our knowledge, the dataset presented in this study includes the first simultaneous records of lightning currents and associated fields featuring ionospheric reflections for natural upward flashes, and the longest distance at which natural upward lightning fields have been measured simultaneously with their causative currents. The intervals between the groundwave and skywave arrival times are used to estimate ionospheric reflection heights during day and night times using the so-called zero-to-zero and peak-to-peak methods. During daytime, the mean ionospheric reflection heights, obtained using the two different delay estimation approaches, are about 78 and 76 km, corresponding to the D layer. The mean reflection height at nighttime is about 90 and 89 km, corresponding to the E layer. We present a full-wave, finite-difference time-domain (FDTD) analysis of the electric field propagation including the effect of the ionospheric reflections. The FDTD simulation results are compared with the measured fields associated with upward flashes initiated from the Säntis Tower. It is found that the model reproduces reasonably well the measured waveforms and the times of arrival of the one-hop and two-hop skywaves relative to the groundwave.

      PubDate: 2017-05-13T03:49:18Z
      DOI: 10.1016/j.jastp.2017.05.010
       
  • Performance of the Angstrom-Prescott Model (A-P) and SVM and ANN
           Techniques to estimate the daily Global Solar Irradiation in
           Botucatu/SP/Brazil
    • Authors: Maurício Bruno Prado da Silva; João Francisco Escobedo; Cícero Manoel dos Santos; Taiza Juliana Rossi; Sílvia Helena Modenese Gorla da Silva
      Abstract: Publication date: Available online 10 May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Maurício Bruno Prado da Silva, João Francisco Escobedo, Cícero Manoel dos Santos, Taiza Juliana Rossi, Sílvia Helena Modenese Gorla da Silva
      This study describes the comparative study of different methods for estimating daily global solar irradiation (HG): Angstrom-Prescott (A-P) model and two Machine Learning techniques (ML) - Support Vector Machine (SVM) and Artificial Neural Network (ANN). The HG database was measured from 1996 to 2011 in Botucatu/SP/Brazil. Different combinations of input variables were adopted. Statistical indicatives MBE, RMSE, d Willmott, r and R2 obtained in the validation of A-P and SVM and ANN models showed that: SVM technique has better performance than A-P and ANN models in estimating HG. The A-P model has better performance than ANN in estimating HG.

      PubDate: 2017-05-13T03:49:18Z
      DOI: 10.1016/j.jastp.2017.04.001
       
  • Variation of the Channel Temperature in the Transmission of Lightning
           Leader
    • Authors: Xuan Chang; Ping Yuan; Jianyong Cen; Xuejuan Wang
      Abstract: Publication date: Available online 10 May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Xuan Chang, Ping Yuan, Jianyong Cen, Xuejuan Wang
      According to the time-resolved spectra of the lightning stepped leader and dart leader processes, the channel temperature, its evolution characteristics with time and the variation along the channel height in the transmission process were analyzed. The results show that the stepped leader tip has a slightly higher temperature than the trailing end, which should be caused by a large amount of electric charges on the leader tip. In addition, both temperature and brightness are enhanced at the position of the channel node. The dart leader has a higher channel temperature than the stepped leader but a lower temperature than the return stroke. Meanwhile, the channel temperature of the dart leader obviously increases when the dart leader propagates to the ground.

      PubDate: 2017-05-13T03:49:18Z
      DOI: 10.1016/j.jastp.2017.04.006
       
  • Modulations of solar activity on El Niño Modoki and possible
           mechanisms
    • Authors: Wenjuan Huo; Ziniu Xiao
      Abstract: Publication date: Available online 10 May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Wenjuan Huo, Ziniu Xiao
      This paper uses the sunspot number (SSN) index and the El Niño modoki index (EMI) to examine the possible modulation of El Niño Modoki events by variations in solar activity. A significant positive correlation was found between SSN and EMI with a lag of two years, and both SSN and EMI have an obvious period of about 11–12 years. The evolution of El Niño Modoki events was investigated using composite analysis. There was a clear evolution of El Niño Modoki events in the three years after the solar peak year. An ocean mixed layer heat budget diagnostic method is used to investigate the contributor to the anomalous patterns in the three years after the solar peak. The atmosphere radiation fluxes are confirmed as the major contributor to the warming response in the central tropical Pacific. Two possible mechanisms are proposed, one is the direct mechanism that the solar radiation warms up the tropical pacific with a geographical difference, due to the cloud distribution. The warming response in the central Pacific is amplified by the coupled positive feedback between the ocean and atmosphere with 1–2 years lag. Another possible way can be described as follows: the solar heating effect propagating from the upper atmosphere modulates the strength and variation of atmospheric anomaly at high and mid-latitudes in the northern hemisphere winter, which results in an anomalous subtropical cyclone over the northeastern Pacific in the winter seasons following the solar peak years. The anomalous cyclone reduces the cloud cover over the northeastern Pacific and enhances the local input of solar radiation. As a result, a positive sea surface temperature (SST) anomaly occurs over the northeastern Pacific and extends towards the central tropical Pacific along the path of anomalous southwesterly winds, which may trigger an El Niño Modoki event in the following years.

      PubDate: 2017-05-13T03:49:18Z
      DOI: 10.1016/j.jastp.2017.05.008
       
  • IFC-Ed. board
    • Abstract: Publication date: May 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 157–158


      PubDate: 2017-05-02T03:06:31Z
       
  • Topside ionospheric effects of the annular solar eclipse of 15th January
           2010 as observed by DEMETER satellite
    • Authors: Surya K Maji; Sandip K Chakrabarti; Dipak Sanki; Sujay Pal
      Abstract: Publication date: Available online 28 April 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Surya K Maji, Sandip K Chakrabarti, Dipak Sanki, Sujay Pal
      We present effects of the annular solar eclipse of 15th January 2010 on the topside ionosphere using the DEMETER satellite data. Measurements of the electron-ion density and electron temperature by the ISL (Instrument Sonde de Langmuir) and IAP (Instrument Analyseur de Plasma) instruments on board the DEMETER satellite during the eclipse time over the low latitude (±40) Indian ocean area are presented. We found the peak decrease in electron density to be about 35% and the peak decrease in ion density to be about 40% from the reference orbits at the altitude of the satellite (∼660km). Electron and ion temperatures were found to have decreased by 200–300K at the same altitude. Instead of simple decrease as in ion density, electron temperature showed a complex wave-like oscillation as the solar eclipse progressed. Electron density decreased to a minimum value before the maximum obscuration and starts to increase before passing through another minimum at the time of maximum obscuration. Both the minima are located at the ± 10 degree geomagnetic latitude. Variations of electron and ion densities were found to follow the average solar illumination experienced by the satellite and its conjugate points at satellite altitude, while the electron temperature showed no such correlation.

      PubDate: 2017-05-02T03:06:31Z
      DOI: 10.1016/j.jastp.2017.04.012
       
  • A study on raindrop size distribution variability in before and after
           
    • Authors: Jayalakshmi Janapati; Balaji Kumar seela; M. Venkatrami Reddy; K. Krishna Reddy; Pay-Liam Lin; T. Narayana Rao; Chian-Yi Liu
      Abstract: Publication date: Available online 28 April 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Jayalakshmi Janapati, Balaji Kumar seela, M. Venkatrami Reddy, K. Krishna Reddy, Pay-Liam Lin, T. Narayana Rao, Chian-Yi Liu
      Raindrop size distribution (RSD) characteristics in before landfall (BLF) and after landfall (ALF) of three tropical cyclones (JAL, THANE, and NILAM) induced precipitations are investigated by using a laser-based (PARticleSIze and VELocity - PARSIVEL) disdrometer at two different locations [Kadapa (14.47°N, 78.82°E) and Gadanki (13.5oN, 79.2oE)] in semi-arid region of southern India. In both BLF and ALF precipitations of these three cyclones, convective precipitations have higher mass weighted mean diameter (Dm) and lower normalized intercept parameter (log10Nw) values than stratiform precipitations. The radar reflectivity (Z) and rain rate (R) relations (Z=A⁎Rb) showed distinct variations in BLF and ALF precipitations of three cyclones. BLF precipitation of JAL cyclone has a higher Dm than ALF precipitation. Whereas, for THANE and NILAM cyclones ALF precipitations have higher Dm than BLF. The Dm values of three cyclones (both in BLF and ALF) are smaller than the Dm values of the other (Atlantic and Pacific) oceanic cyclones. Interaction of different regions (eyewall, inner rainbands, and outer rainbands) of cyclones with the environment and underlying surface led to RSD variations between BLF and ALF precipitations through different microphysical (collision-coalescence, breakup, evaporation, and riming) processes. The immediate significance of the present work is that (i) it contributes to our understanding of cyclone RSD in BLF and ALF precipitations, and (ii) it provides the useful information for quantitative estimation of rainfall from Doppler weather radar observations.

      PubDate: 2017-05-02T03:06:31Z
      DOI: 10.1016/j.jastp.2017.04.011
       
  • Comparisons of planetary wave propagation to the upper atmosphere during
           stratospheric warming events at different QBO phases
    • Authors: Andrey V. Koval; Nikolai M. Gavrilov; Alexander I. Pogoreltsev; Elena N. Savenkova
      Abstract: Publication date: Available online 27 April 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Andrey V. Koval, Nikolai M. Gavrilov, Alexander I. Pogoreltsev, Elena N. Savenkova
      The dynamical coupling of the lower and upper atmosphere by planetary waves (PWs) is studied. Numerical simulations of planetary wave (PW) amplitudes during composite sudden stratospheric warming (SSW) events in January-February are made using a model of general circulation of the middle and upper atmosphere with initial and boundary conditions typical for the westerly and easterly phases of quasi-biennial oscillation (QBO). The changes in PW amplitudes in the middle atmosphere before, during and after SSW event for the different QBO phases are considered. Near the North Pole, the increase in the mean temperature during SSW reaches 10–30K at altitudes 30–50km for four pairs of the model runs with the eQBO and wQBO, which is characteristic for the sudden stratospheric warming event. Amplitudes of stationary PWs in the middle atmosphere of the Northern hemisphere may differ up to 30% during wQBO and eQBO before and during the SSW. After the SSW event SPW amplitudes are substantially larger during wQBO phase. PW refractivity indices and Eliassen-Palm flux vectors are calculated. The largest EP-fluxes in the middle atmosphere correspond to PWs with zonal wavenumber m=1. Simulated changes in PW amplitudes correspond to inhomogeneities of the global circulation, refractivity index and EP-flux produced by the changes in QBO phases. Comparisons of differences in PW characteristics and circulation between the wQBO and eQBO show that PWs could provide effective coupling mechanism and transport dynamical changes from local regions of the lower atmosphere to distant regions of the upper atmosphere of both hemispheres.

      PubDate: 2017-05-02T03:06:31Z
      DOI: 10.1016/j.jastp.2017.04.013
       
  • Variability of OH(3-1) and OH(6-2) emission altitude and volume emission
           rate from 2003 to 2011
    • Authors: Georg Teiser; Christian von Savigny
      Abstract: Publication date: Available online 26 April 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Georg Teiser, Christian von Savigny
      In this study we report on variability in emission rate and centroid emission altitude of the OH(3-1) and OH(6-2) Meinel bands in the terrestrial nightglow based on spaceborne nightglow measurements with the SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) instrument on the Envisat satellite. The SCIAMACHY observations cover the time period from August 2002 to April 2012 and the nighttime observations used in this study are performed at 10:00p.m. local solar time. Characterizing variability in OH emission altitude – particularly potential long-term variations – is important for an appropriate interpretation of ground-based OH rotational temperature measurements, because simultaneous observations of the vertical OH volume emission rate profile are usually not available for these measurements. OH emission altitude and vertically integrated emission rate time series with daily resolution for the OH(3-1) band and monthly resolution for the OH(6-2) band were analyzed using a standard multilinear regression approach allowing for seasonal variations, QBO-effects (Quasi-Biennial Oscillation), solar cycle (SC) variability and a linear long-term trend. The analysis focuses on low latitudes, where SCIAMACHY nighttime observations are available all year. The dominant sources of variability for both OH emission rate and altitude are the semi-annual and annual variations, with emission rate and altitude being highly anti-correlated. There is some evidence for a 11-year solar cycle signature in the vertically integrated emission rate and in the centroid emission altitude of both the OH(3-1) and OH(6-2) bands.

      PubDate: 2017-05-02T03:06:31Z
      DOI: 10.1016/j.jastp.2017.04.010
       
  • Equivalent slab thickness of the ionosphere over Europe as an indicator of
           long-term temperature changes in the thermosphere
    • Authors: Norbert Jakowski; Mohammed Mainul Hoque; Jens Mielich; Chris Hall
      Abstract: Publication date: Available online 25 April 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Norbert Jakowski, Mohammed Mainul Hoque, Jens Mielich, Chris Hall
      Simultaneous measurements of the total electron content (TEC) and the peak electron density NmF2 at vertical sounding stations enable the estimation of the equivalent slab thickness of the ionosphere. This shape parameter, defined as the ratio of the observables TEC and NmF2 of the vertical electron density profile, is closely related to the neutral gas scale height under steady-state conditions at daytime. In this paper we present for the first time a long term trend (LTT) analysis of the equivalent slab thickness for estimating long term trends of thermospheric temperature changes. The analysis is made for 5 vertical sounding stations located in the latitude range 40 – 70°N in Europe and covers the entire solar cycle 23 during the years 1995 – 2009. The observations indicate a long term decrease of the equivalent slab thickness at all ionosonde stations considered here from 11 – 62km/decade with increasing tendency towards higher latitudes. Since the seasonal dynamics of the slab thickness clearly overestimates expected temperature changes, it has been found that composition changes, in particular the atomic oxygen/molecular nitrogen density ratio, contribute essentially to the high dynamics of the equivalent slab thickness closely associated with the occurrence of the well-known daytime winter anomaly in Northern mid-latitudes. In analogy, to explain remaining temperature overestimates in the long term trends of the equivalent slab thickness, it is assumed that a long term increase of the atomic oxygen/molecular nitrogen density ratio exist. So the contraction (decrease of scale height and equivalent slab thickness) and the lowering (decrease of the peak density height hmF2) of the electron density profile can be understood in a consistent manner. It is demonstrated that a permanent monitoring of the equivalent slab thickness can contribute to explore long term changes of the thermosphere. To get quantitative estimates of thermospheric temperature changes based on this new LTT monitoring technique, more detailed studies including first principles models are needed.

      PubDate: 2017-04-25T02:54:04Z
      DOI: 10.1016/j.jastp.2017.04.008
       
  • Long-Term Trends in the D- and E-Region Based on Rocket-Borne Measurements
    • Authors: M. Friedrich; C. Pock; K. Torkar
      Abstract: Publication date: Available online 25 April 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): M. Friedrich, C. Pock, K. Torkar
      Electron densities obtained from rocket borne measurements are compared to an empirical, steady state model built from these data. The ratios between each measured value and its corresponding model value vs. time yield trends which significantly vary with altitude. Notably above 120 to 130km the electron densities generally increase, whereas between 95 and 120km the ionosphere appears stable. Somewhere below 80 to 90km - depending on the investigated data subset - there is again a positive trend down to below 70km. Tentative explanations such as cooling of the mesosphere are suggested and may be confirmed by comprehensive theoretical models of the upper atmosphere.

      PubDate: 2017-04-25T02:54:04Z
      DOI: 10.1016/j.jastp.2017.04.009
       
  • Mesospheric Temperature Trends derived from Standard Phase-Height
           Measurements
    • Authors: Dieter H.W. Peters; Günter Entzian; Philippe Keckhut
      Abstract: Publication date: Available online 22 April 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Dieter H.W. Peters, Günter Entzian, Philippe Keckhut
      New homogeneous time series of daily standard phase-height (SPH) and daily plasma scale-height (PSH) have been derived from a 50-year long-radio-wave measurement of the broadcasting station Allouis (France, 162kHz). The signal was received at Kühlungsborn (54°N, 12°E, Mecklenburg, Germany) and the present series is a third release. The daily time series of SPH shows in its spectrum dominant modes which are typical for the solar cycle (SC), for El Niño-Southern Oscillation (ENSO) and for quasi-biannual oscillation (QBO), indicating solar and lower atmospheric influences. Surprisingly, the time series of daily PSH shows a band of dominant cycles larger than 16 years. In order to exclude the influence of the winter anomaly in the determination of column-integrated mesospheric temperature trends the phase-height-temperature procedure is confined to summer months. The derived thickness temperature of the mesosphere decreased statistically significant over the period 1959–2008 after pre-whitening with summer mean of solar sun spot numbers. The trend value is in the order of about −1.05K / decade if the stratopause trend is excluded. The linear regression is more pronounced, −1.35K / decade for the period of 1963–1985 (2 SCs), but weaker, −0.51K / decade during 1986-08 (last 2 SCs). The linear regression is in very good agreement with a mean column-integrated mesospheric trend derived from OHP-Lidar temperatures on a monthly mean basis for the last two SCs. This clearly shows that the thickness temperature of the mesosphere derived from phase-height measurement is a useful proxy for the long-term summer temperature change in the mesosphere from 1959 until 2008.

      PubDate: 2017-04-25T02:54:04Z
      DOI: 10.1016/j.jastp.2017.04.007
       
  • Ionospheric effects of magneto-acoustic-gravity waves: Dispersion relation
    • Authors: R. Michael Jones; Lev A. Ostrovsky; Alfred J. Bedard
      Abstract: Publication date: Available online 20 April 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): R. Michael Jones, Lev A. Ostrovsky, Alfred J. Bedard
      There is extensive evidence for ionospheric effects associated with earthquake-related atmospheric disturbances. Although the existence of earthquake precursors is controversial, one suggested method of detecting possible earthquake precursors and tsunamis is by observing possible ionospheric effects of atmospheric waves generated by such events. To study magneto-acoustic-gravity waves in the atmosphere, we have derived a general dispersion relation including the effects of the Earth's magnetic field. This dispersion relation can be used in a general atmospheric ray tracing program to calculate the propagation of magneto-acoustic-gravity waves from the ground to the ionosphere. The presence of the Earth's magnetic field in the ionosphere can radically change the dispersion properties of the wave. The general dispersion relation obtained here reduces to the known dispersion relations for magnetoacoustic waves and acoustic-gravity waves in the corresponding particular cases. As far as we know, no ray tracing program is now available to calculate the propagation of magneto-acoustic-gravity waves or just magnetoacoustic waves in the atmosphere. The work described here is the first step in achieving a generalized ray tracing program permitting propagation studies of magneto-acoustic-gravity waves.

      PubDate: 2017-04-25T02:54:04Z
      DOI: 10.1016/j.jastp.2017.04.004
       
  • IFC-Ed. board
    • Abstract: Publication date: April 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 156


      PubDate: 2017-04-03T16:22:02Z
       
  • Interplanetary Drivers of Daytime Penetration Electric Field into
           Equatorial Ionosphere during CIR-Induced Geomagnetic Storms
    • Authors: Thana Yeeram
      Abstract: Publication date: Available online 21 February 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Thana Yeeram
      Observations based on the magnetometer data of the response of the daytime equatorial electric field to the geomagnetic storms induced by corotating interaction regions (CIRs) during 2007 – 2010 reveal many events of striking long duration of multiple short-lived prompt penetration electric fields (PPEFs). The PPEFs essentially occurred in the main phase of the storms, which are associated with the ring current and magnetic reconnection of the southward z-component of the interplanetary magnetic field (IMF Bz) in relation to the Alfvén waves. The behaviors of the electric field penetration during the storms are consistent with the shielding theory. Particularly, the PPEF is found to be complex due to transient variations in the solar wind dynamic pressure (SWDP) and the IMF Bz in the CIRs. The PPEF is temporary suppressed for about an hour under a shock in association with a drop in the SWDP. The interplanetary electric field Ey is the main driver of the PPEFs, when the solar wind speed, SWDP, and the symmetric ring current are nearly constant, even in the recovery phase. The PPEF is allowed under the condition of high and variable SWDP. The shocks with a northward IMF Bz shield the PPEFs when the SWDP is nearly constant. The partial ring current is strongest in the large and northward IMF Bz, where the shielding effect is greater than the undershielding caused by the large SWDP. The results may provide an important step to study equatorial and low latitude ionospheric electrodynamics in the solar minimum conditions.

      PubDate: 2017-02-23T12:45:38Z
      DOI: 10.1016/j.jastp.2017.02.008
       
 
 
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