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  Subjects -> METEOROLOGY (Total: 82 journals)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 2)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 6)
Advances in Climate Change Research     Open Access  
Advances in Meteorology     Open Access   (Followers: 5)
Aeolian Research     Hybrid Journal   (Followers: 3)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 6)
American Journal of Climate Change     Open Access   (Followers: 7)
Asian Journal of Earth Sciences     Open Access   (Followers: 20)
Atmósfera     Open Access  
Atmosphere     Open Access   (Followers: 4)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 7)
Atmospheric Chemistry and Physics (ACP)     Open Access   (Followers: 13)
Atmospheric Chemistry and Physics Discussions (ACPD)     Open Access   (Followers: 7)
Atmospheric Research     Hybrid Journal   (Followers: 20)
Atmospheric Science Letters     Hybrid Journal   (Followers: 8)
Boundary-Layer Meteorology     Hybrid Journal   (Followers: 10)
Bulletin of the American Meteorological Society     Open Access   (Followers: 14)
Carbon Balance and Management     Open Access   (Followers: 5)
Change and Adaptation in Socio-Ecological Systems     Open Access  
Climate     Open Access   (Followers: 2)
Climate Change Economics     Hybrid Journal   (Followers: 16)
Climate Change Responses     Open Access  
Climate Dynamics     Hybrid Journal   (Followers: 14)
Climate law     Hybrid Journal   (Followers: 3)
Climate of the Past (CP)     Open Access   (Followers: 4)
Climate of the Past Discussions (CPD)     Open Access   (Followers: 2)
Climate Policy     Hybrid Journal   (Followers: 22)
Climate Risk Management     Open Access  
Climatic Change     Hybrid Journal   (Followers: 33)
Current Climate Change Reports     Hybrid Journal  
Developments in Atmospheric Science     Full-text available via subscription   (Followers: 4)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 3)
Earth Perspectives - Transdisciplinarity Enabled     Open Access   (Followers: 1)
Energy & Environment     Full-text available via subscription   (Followers: 17)
Environmental and Climate Technologies     Open Access   (Followers: 2)
Global Meteorology     Open Access  
International Journal of Atmospheric Sciences     Open Access   (Followers: 4)
International Journal of Biometeorology     Hybrid Journal   (Followers: 1)
International Journal of Climate Change Strategies and Management     Hybrid Journal   (Followers: 9)
International Journal of Climatology     Hybrid Journal   (Followers: 15)
International Journal of Image and Data Fusion     Hybrid Journal   (Followers: 1)
Journal of Applied Meteorology and Climatology     Full-text available via subscription   (Followers: 8)
Journal of Atmospheric and Oceanic Technology     Full-text available via subscription   (Followers: 11)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 15)
Journal of Atmospheric Chemistry     Hybrid Journal   (Followers: 2)
Journal of Climate     Full-text available via subscription   (Followers: 27)
Journal of Climatology     Open Access   (Followers: 1)
Journal of Hydrology and Meteorology     Open Access   (Followers: 4)
Journal of Hydrometeorology     Full-text available via subscription   (Followers: 3)
Journal of Integrative Environmental Sciences     Hybrid Journal   (Followers: 4)
Journal of Meteorology and Climate Science     Full-text available via subscription   (Followers: 1)
Journal of Space Weather and Space Climate     Open Access   (Followers: 4)
Journal of the Atmospheric Sciences     Full-text available via subscription   (Followers: 27)
Journal of Weather Modification     Full-text available via subscription  
Large Marine Ecosystems     Full-text available via subscription   (Followers: 1)
Meteorologica     Open Access  
Meteorological Applications     Hybrid Journal   (Followers: 1)
Meteorologische Zeitschrift     Full-text available via subscription   (Followers: 2)
Meteorology and Atmospheric Physics     Hybrid Journal   (Followers: 5)
Mètode Science Studies Journal : Annual Review     Open Access  
Michigan Journal of Sustainability     Open Access  
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 2)
Monthly Notices of the Royal Astronomical Society Letters     Hybrid Journal   (Followers: 3)
Monthly Weather Review     Full-text available via subscription   (Followers: 13)
Nature Climate Change     Full-text available via subscription   (Followers: 41)
Nature Reports Climate Change     Full-text available via subscription   (Followers: 17)
Open Journal of Modern Hydrology     Open Access   (Followers: 3)
Revista Brasileira de Meteorologia     Open Access   (Followers: 1)
Russian Meteorology and Hydrology     Hybrid Journal   (Followers: 4)
Space Weather     Full-text available via subscription   (Followers: 3)
Studia Geophysica et Geodaetica     Hybrid Journal   (Followers: 3)
Tellus A     Open Access   (Followers: 4)
Tellus B     Open Access   (Followers: 6)
The Cryosphere (TC)     Open Access   (Followers: 2)
The Cryosphere Discussions (TCD)     Open Access   (Followers: 1)
The Quarterly Journal of the Royal Meteorological Society     Hybrid Journal   (Followers: 7)
Theoretical and Applied Climatology     Hybrid Journal   (Followers: 2)
Weather     Hybrid Journal   (Followers: 2)
Weather and Climate Extremes     Open Access   (Followers: 2)
Weather and Forecasting     Full-text available via subscription   (Followers: 2)
Weatherwise     Hybrid Journal  
气候与环境研究     Full-text available via subscription  
Journal Cover   Journal of Atmospheric and Solar-Terrestrial Physics
  [SJR: 1.045]   [H-I: 61]   [15 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1364-6826
   Published by Elsevier Homepage  [2812 journals]
  • Study of surface ozone at Port Blair, India, a remote marine station in
           the Bay of Bengal
    • Abstract: Publication date: July 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 129
      Author(s): T.K. Mandal , S.K. Peshin , C. Sharma , Prabhat Kumar Gupta , Rachit Raj , S.K. Sharma
      This paper presents seasonal variation of surface ozone monitored continuously at site of the meteorological observatory at Port Blair, a maritime site of the Bay of Bengal for the period of August, 2005–March, 2007. Present observation depicts the characteristics of surface ozone at the remote marine site and the long range transport of pollutants from three different sides i.e., Indian Subcontinent, South East Asia and Indian Ocean. Very high ozone mixing ratio (~70–80ppbv) is occasionally observed during March and November at this site. A campaign mode of observation of trace gases (surface ozone, CO, NO x , CO2), aerosol concentration and its size, UV radiation at Port Blair was made to understand the role of transport on pollutants during March 16–26, 2002. During this period of observation, a near zero surface ozone of different time scales (~few hours) has been observed several times during the period of midnight to early morning. Simultaneously NO x (NO+NO2) (~40ppbv) and carbon monoxide was observed very high (300–600ppbv) during this period. Source of this high pollutant are not expected at this remote marine sites although wind patterns, 7-days isentropic back Trajectory analysis and MATCH Model output suggest that polluted air mass has come from eastern side of Indian subcontinent.


      PubDate: 2015-05-24T12:01:13Z
       
  • Variability of the quasi-2-day wave and interaction with longer period
           
    • Abstract: Publication date: Available online 19 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): A. Guharay , P.P. Batista , B.R. Clemesha
      An exclusive study has been carried out with long term meteor wind data (2000-2014) to characterize the quasi-2-day wave (QTDW) in the mesosphere and lower thermosphere (MLT) and its interactions with the longer period planetary waves at Cachoeira Paulista (22.7°S, 45°W). The QTDW is observed to be dominant during late summer (January-February) all the years under consideration except 2013. All the wave parameters exhibit significant interannual variability. The maximum wave amplitude comes out to be 39m/s, which is significantly higher than the reported northern hemispheric findings. The mean MLT period exhibits a wide range of variability (36-70h) indicating the presence of multiple Rossby normal modes with varying zonal wave numbers. Modulations of the QTDW amplitude by the planetary waves with longer periodicities (>9 days) are evident, especially during summer. The nonlinear interactions between the 2-day wave and longer period waves are believed to give rise to a host of secondary waves with frequencies lying close to 2-day. The strong QTDW activity, as observed at this location, has potential to cause significant effect on the overlying ionosphere and hence the atmosphere-ionosphere dynamical coupling.


      PubDate: 2015-05-20T11:32:38Z
       
  • Fe embedded in ice: The impacts of sublimation and energetic particle
           bombardment
    • Abstract: Publication date: May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 127
      Author(s): Victoria L. Frankland , John M.C. Plane
      Icy particles containing a variety of Fe compounds are present in the upper atmospheres of planets such as the Earth and Saturn. In order to explore the role of ice sublimation and energetic ion bombardment in releasing Fe species into the gas phase, Fe-dosed ice films were prepared under UHV conditions in the laboratory. Temperature-programmed desorption studies of Fe/H2O films revealed that no Fe atoms or Fe-containing species co-desorbed along with the H2O molecules. This implies that when noctilucent ice cloud particles sublimate in the terrestrial mesosphere, the metallic species embedded in them will coalesce to form residual particles. Sputtering of the Fe-ice films by energetic Ar+ ions was shown to be an efficient mechanism for releasing Fe into the gas phase, with a yield of 0.08 (Ar+ energy=600eV). Extrapolating with a semi-empirical sputtering model to the conditions of a proton aurora indicates that sputtering by energetic protons (>100keV) should also be efficient. However, the proton flux in even an intense aurora will be too low for the resulting injection of Fe species into the gas phase to compete with that from meteoric ablation. In contrast, sputtering of the icy particles in the main rings of Saturn by energetic O+ ions may be the source of recently observed Fe+ in the Saturnian magnetosphere. Electron sputtering (9.5keV) produced no detectable Fe atoms or Fe-containing species. Finally, it was observed that Fe(OH)2 was produced when Fe was dosed onto an ice film at 140K (but not at 95K). Electronic structure theory shows that the reaction which forms this hydroxide from adsorbed Fe has a large barrier of about 0.7eV, from which we conclude that the reaction requires both translationally hot Fe atoms and mobile H2O molecules on the ice surface.


      PubDate: 2015-05-16T11:18:16Z
       
  • The crystal structure of ice under mesospheric conditions
    • Abstract: Publication date: May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 127
      Author(s): Benjamin J. Murray , Tamsin L. Malkin , Christoph G. Salzmann
      Ice clouds form in the summer high latitude mesopause region, which is the coldest part of the Earth's atmosphere. At these very low temperatures (<150K) ice can exist in metastable forms, but the nature of these ices remains poorly understood. In this paper we show that ice which is grown at mesospherically relevant temperatures does not have a structure corresponding to the well-known hexagonal form or the metastable cubic form. Instead, the ice which forms under mesospheric conditions is a material in which cubic and hexagonal sequences of ice are randomly arranged to produce stacking disordered ice (ice Isd). The structure of this ice is in the trigonal crystal system, rather than the cubic or hexagonal systems, and is expected to produce crystals with aspect ratios consistent with lidar observations.


      PubDate: 2015-05-16T11:18:16Z
       
  • Study on morphology and growth of water–ice grains spontaneously
           generated in a laboratory plasma
    • Abstract: Publication date: May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 127
      Author(s): Kil-Byoung Chai , Paul M. Bellan
      An apparatus has been developed to study the nucleation, growth, and morphology of water–ice grains spontaneously generated in a weakly ionized plasma having very cold neutral particles. Nucleation of water–ice grains in the laboratory experiment occurs only when plasma exists but the plasma density is not too high. Nonspherical, fast growth occurs when the mean free path of water molecules exceeds the screening length for the ice grain in which case molecules incident on the ice grain can be considered to have collisionless trajectories. High water vapor pressure enhances this nonspherical, fast growth provided the collisionless condition is satisfied. Magnetic field impedes nonspherical growth by reducing the charge residing on water–ice grains if the field is sufficiently strong to make the electron gyro radius smaller than the ice grain screening length.


      PubDate: 2015-05-16T11:18:16Z
       
  • On the early onset of the NLC season 2013 as observed at ALOMAR
    • Abstract: Publication date: May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 127
      Author(s): Jens Fiedler , Gerd Baumgarten , Uwe Berger , Axel Gabriel , Ralph Latteck , Franz-Josef Lübken
      On 21 May the ALOMAR RMR-lidar in Northern Norway detected the first noctilucent clouds (NLC) in 2013. This unusual early NLC onset was accompanied by ∼6K lower temperatures and higher water vapor mixing ratios at NLC altitudes from the end of April until the beginning of June. The zonal mean temperature and dynamic conditions in the Arctic middle atmosphere deviated in spring 2013 significantly from the mean conditions of the last 20years. Furthermore the planetary wave activity in the high latitude stratosphere was enhanced from 20 April to beginning of May. The colder and wetter upper mesosphere in May 2013 is attributed to this unusual late planetary wave activity in the stratosphere, introducing a strong upwelling in the mesosphere, lower temperatures and an upward transport of water vapor, which finally resulted in earlier existence conditions for mesospheric ice particles. We regard this as a first evidence for intra-hemispheric coupling in the northern hemisphere extending from the stratosphere into the mesopause region. Yet it is unclear whether this is an unusual extreme event or an indicator for a change in the circulation due to the observed long-term cooling of the middle atmosphere.


      PubDate: 2015-05-16T11:18:16Z
       
  • The fractal perimeter dimension of noctilucent clouds: Sensitivity
           analysis of the area–perimeter method and results on the seasonal
           and hemispheric dependence of the fractal dimension
    • Abstract: Publication date: May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 127
      Author(s): L.A. Brinkhoff , C. von Savigny , C.E. Randall , J.P. Burrows
      The fractal perimeter dimension is a fundamental property of clouds. It describes the cloud shape and is used to improve the understanding of atmospheric processes responsible for cloud shapes. von Savigny et al. (2011) determined the fractal perimeter dimension of noctilucent clouds (or polar mesospheric clouds) for the first time based on a limited data set of cloud images observed with the CIPS (Cloud Imaging and Particle Size) instrument on board the AIM (Aeronomy of Ice in the Mesosphere) satellite. This paper builds on von Savigny et al. (2011) by first presenting a sensitivity analysis of the determination of the fractal perimeter dimension, and secondly presenting results on the seasonal and interhemispheric differences of the perimeter dimension of noctilucent clouds (NLCs). The same method as in the earlier study is applied to an extended data set of satellite images of noctilucent cloud fields taken with the CIPS experiment. The sensitivity studies reveal that cloud holes play an important role for the area–perimeter method, since excluding clouds with holes reduces the dimension value by up to 3%. The results on the fractal perimeter dimension over six NLC seasons from 2007 to 2009 demonstrate that the dimension values of the NLCs neither show significant differences between the seasons nor between the hemispheres.
      Graphical abstract image Highlights

      PubDate: 2015-05-16T11:18:16Z
       
  • Comparing nadir and limb observations of polar mesospheric clouds: The
           effect of the assumed particle size distribution
    • Abstract: Publication date: May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 127
      Author(s): Scott M. Bailey , Gary E. Thomas , Mark E. Hervig , Jerry D. Lumpe , Cora E. Randall , Justin N. Carstens , Brentha Thurairajah , David W. Rusch , James M. Russell III , Larry L. Gordley
      Nadir viewing observations of Polar Mesospheric Clouds (PMCs) from the Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) spacecraft are compared to Common Volume (CV), limb-viewing observations by the Solar Occultation For Ice Experiment (SOFIE) also on AIM. CIPS makes multiple observations of PMC-scattered UV sunlight from a given location at a variety of geometries and uses the variation of the radiance with scattering angle to determine a cloud albedo, particle size distribution, and Ice Water Content (IWC). SOFIE uses IR solar occultation in 16 channels (0.3–5μm) to obtain altitude profiles of ice properties including the particle size distribution and IWC in addition to temperature, water vapor abundance, and other environmental parameters. CIPS and SOFIE made CV observations from 2007 to 2009. In order to compare the CV observations from the two instruments, SOFIE observations are used to predict the mean PMC properties observed by CIPS. Initial agreement is poor with SOFIE predicting particle size distributions with systematically smaller mean radii and a factor of two more albedo and IWC than observed by CIPS. We show that significantly improved agreement is obtained if the PMC ice is assumed to contain 0.5% meteoric smoke by mass, in agreement with previous studies. We show that the comparison is further improved if an adjustment is made in the CIPS data processing regarding the removal of Rayleigh scattered sunlight below the clouds. This change has an effect on the CV PMC, but is negligible for most of the observed clouds outside the CV. Finally, we examine the role of the assumed shape of the ice particle size distribution. Both experiments nominally assume the shape is Gaussian with a width parameter roughly half of the mean radius. We analyze modeled ice particle distributions and show that, for the column integrated ice distribution, Log-normal and Exponential distributions better represent the range of masses that contribute to the IWC. We further show that agreement between SOFIE and CIPS is further improved with the assumption of either Log-normal or Exponential ice particle size distributions. This improvement suggests that the range of mass bearing particle radii is larger, but not significantly shifted from what is obtained by assuming a Gaussian distribution. The assumption of an Exponential particle size distribution, as shown to be justifiable here, has the attractive benefits of being characterized with a single parameter, the mean radius, which greatly facilitates studies of the spatial and temporal variation of PMC particle size distributions as well as comparisons between observations and models. Overall, our results represent a validation of both the CIPS and SOFIE datasets.


      PubDate: 2015-05-16T11:18:16Z
       
  • Tidal signatures in temperatures derived from daylight lidar soundings
           above Kühlungsborn (54°N, 12°E)
    • Abstract: Publication date: May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 127
      Author(s): M. Kopp , M. Gerding , J. Höffner , F.-J. Lübken
      We have developed a new Rayleigh–Mie–Raman (RMR) lidar at the mid-latitude station in Kühlungsborn (54°N, 12°E) for analyzing geophysical phenomena at day and night, e.g., temperature tides and Noctilucent Clouds. For this study we have used about 3100h of data since April 2011 with additional data from summer 2010. The RMR lidar was in operation day and night in addition to the existing daylight-capable potassium resonance lidar. We show for the first time an overview of the altitude structure and seasonal variation of temperature tides, observed with lidars between 40 and 100km altitude at a mid-latitude site. There is a gap around 80km altitude due to a decreasing signal-to-noise ratio during the day. We derive mean tidal amplitudes and phases with 24-, 12-, and 8-h period. In most of the months, the diurnal component dominates the other tidal components with mean amplitudes of 1–2K in the stratopause region (45–55km altitude), where it is up to three times higher than semidiurnal and terdiurnal tidal amplitudes. The diurnal tide is damped at ∼60km altitude. In the mid-mesosphere (65–70km) diurnal, semidiurnal, and terdiurnal tidal components have comparable mean amplitudes of about 1–1.5K, except around the equinoxes. Around the mesopause the diurnal tide dominates again, with mean amplitudes of about 4K, but with a large variability. The seasonal variation shows a conspicuous structure below ∼65km altitude with tidal amplitudes small in summer and large around the equinoxes. This structure vanishes above ∼65km. There, the amplitude increases in summer. The measured tidal amplitudes and phases are compared with the MERRA (Modern Era Retrospective analysis for Research and Applications) reanalysis data. Repeated soundings in subsequent years allow to examine the year-to-year variation. The data from March in both 2012 and 2013 show a prominent diurnal tide at around 45km altitude with amplitudes about three times larger than in the other months. The short-term variability can be examined from continuous lidar operations during clear-sky periods. In a case study we show a large variability of the tidal amplitudes, especially the 8-h variation. This can only be examined due to a good temporal coverage of the lidar data.


      PubDate: 2015-05-16T11:18:16Z
       
  • The seasonal cycle of gravity wave momentum flux and forcing in the high
           latitude northern hemisphere mesopause region
    • Abstract: Publication date: May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 127
      Author(s): R.J. de Wit , R.E. Hibbins , P.J. Espy
      A new generation all-sky SKiYMET meteor radar, optimized to measure high-frequency gravity wave momentum flux, was installed in Trondheim, Norway (63.4°N, 10.5°E), and has been providing near-continuous measurements since September 2012. Using the system's first full calendar year of observations the seasonal cycle of gravity wave momentum flux and forcing in the mesopause region is studied. The vertical flux of zonal momentum is observed to change from westward to eastward with increasing altitude in winter, and from eastward to westward in summer. This vertical divergence results in westward gravity wave forcing in winter, and eastward forcing in summer. It is shown that the seasonal cycle in gravity wave momentum flux and forcing can be interpreted in terms of selective filtering of a uniform spectrum of vertically propagating GWs between the surface and the mesopause region.


      PubDate: 2015-05-16T11:18:16Z
       
  • Characterisation of quasi-stationary planetary waves in the Northern MLT
           during summer
    • Abstract: Publication date: May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 127
      Author(s): Nora H. Stray , Patrick J. Espy , Varavut Limpasuvan , Robert E. Hibbins
      Observations of planetary wave (PW) activity in the northern hemisphere, polar summer mesosphere and lower thermosphere (MLT) are presented. Meteor winds from a northern hemisphere chain of SuperDARN radars have been used to monitor the meridional wind along a latitude band (51–66°N) in the MLT. A stationary PW-like longitudinal structure with a strong zonal PW number 1 characteristic is persistently observed year-to-year during summer. Here we characterize the amplitude and the phase structure of this wave in the MLT. The Modern-Era Retrospective Analysis for Research and Application (MERRA) of the NASA Global Modelling and Assimilation Office has been used to evaluate possible sources of the observed longitudinal perturbation in the mesospheric meridional wind by investigating the amplitudes and phases of PWs in the underlying atmosphere. The investigation shows that neither gravity wave modulation by lower atmospheric PWs nor direct propagation of PWs from the lower atmosphere are a significant cause of the observed longitudinal perturbation. However, the data are not of sufficient scope to investigate longitudinal differences in gravity wave sources, or to separate the effects of instabilities and inter-hemispheric propagation as possible causes for the large PW present in the summer MLT.


      PubDate: 2015-05-16T11:18:16Z
       
  • IFC-Ed. board
    • Abstract: Publication date: May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 127




      PubDate: 2015-05-16T11:18:16Z
       
  • Wavelength dependence of the effective cloud optical depth
    • Abstract: Publication date: Available online 11 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): D. Serrano , M.J. Marín , M. Núñez , M.P. Utrillas , S. Gandía , J.A. Martínez-Lozano
      This study examines the wavelength dependence of cloud optical depth. To accomplish this task two different wavelength bands of the solar spectrum were considered in the cloud optical depth retrieval which was conducted in Valencia, Spain. The first retrieval used global irradiance measurements in the UVER range taken from a YES-UVB-1 radiometer in combination with multiple scattering model estimates; while the second retrieval was obtained in the Broadband range, with measurements of global solar surface irradiance from a CM6 pyranometer and a multiple scattering model. Whilst the dependence of the cloud optical depth (τ) on the wavelength is small, the best result was displayed by the SBDART model with less than 2% deviation between two ranges and moderately worse results were obtained with the LibRadtran model. Finally, seasonal statistical data for optical depth are presented for 2011 and 2012.


      PubDate: 2015-05-16T11:18:16Z
       
  • Simultaneous retrieval of T(p) and CO2 VMR from two-channel non-LTE limb
           radiances and application to daytime SABER/TIMED measurements
    • Abstract: Publication date: Available online 11 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): L. Rezac , A. Kutepov , J.M. Russell III , A.G. Feofilov , J. Yue , R.A. Goldberg
      The kinetic temperature, T k , and carbon dioxide, CO2 density, are key parameters that characterize the energetics and dynamics of the mesosphere and lower thermosphere (MLT) region. The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on-board the Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (TIMED) satellite has been providing global, simultaneous measurements of limb radiance in 10 spectral channels continuously since late January 2002. In this paper we (1) present a methodology for a self-consistent simultaneous retrieval of temperature/pressure, T k (p), and CO2 volume mixing ratio (VMR) from the broadband infrared limb measurements in the 15 and 4.3 μ m channels, and (2) qualitatively describe the first results on the CO2 VMR and T k obtained from application of this technique to the SABER 15 and 4.3 μ m channels, including issues, which demand additional constrains to be applied. The self-consistent two-channel retrieval architecture updates parameters at all altitudes simultaneously, and it is built upon iterative switching between two retrieval modules, one for CO2 and one for T k . A detailed study of sensitivity, stability and convergence was carried out to validate the algorithm. The T k /CO2 VMR distribution can be reliably retrieved without biases connected with this non-linear inverse problem starting with an initial guess as far as ±20% of CO2 VMR and ±15K from the solution (as global shift, or somewhat larger if only local deviations are considered). In polar summer toward high latitudes the retrieved CO2 VMR profile shows a local peak around 90km. We discuss details of this feature an show that: (a) it is not an algorithm artifact or instability, (b) additional a-priori constraints are needed in order to obtain a physical profile and to remove this peak, and (c) several possibilities are explored as to uncover the real cause of this feature, but no firm conclusion can be reached at this time. This algorithm has been applied to all available daytime SABER measurements since 2002, and the first results of the mean CO2 VMR profiles and their distribution is discussed. In particular, the CO2 VMR profiles depart from a well mixed value at altitudes of 65–70km during equinoxes at high and mid-latitudes, but in the summer hemisphere solstice period the SABER data is more consistent with a well mixed VMR conditions extend up to 87–90km especially toward high latitudes.


      PubDate: 2015-05-16T11:18:16Z
       
  • Ionospheric electron density profileEstimation using Commercial AM
           Broadcast Signals
    • Abstract: Publication date: Available online 12 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): De Yu , Hong Ma , Li Cheng , Yang Li , Yufeng Zhang , Wenjun Chen
      A new method for estimating the bottom electron density profile by using commercial AM broadcast signals as non-cooperative signals is presented in this paper. Without requiring any dedicated transmitters, the required input data are the measured elevation angles of signals transmitted from the known locations of broadcast stations. The input data are inverted for the QPS model parameters depicting the electron density profile of the signal’s reflection area by using a probabilistic inversion technique. This method has been validated on synthesized data and used with the real data provided by an HF direction-finding system situated near the city of Wuhan. The estimated parameters obtained by the proposed method have been compared with vertical ionosonde data and have been used to locate the Shijiazhuang broadcast station. The simulation and experimental results indicate that the proposed ionospheric sounding method is feasible for obtaining useful electron density profiles.


      PubDate: 2015-05-16T11:18:16Z
       
  • Synoptic Kelvin type perturbation waves over Congo basin over the period
           1979-2010
    • Abstract: Publication date: Available online 13 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Zebaze Sinclaire , André Lenouo , Clément Tchawoua , Serge Janicot
      The synoptic structure and inter-annual variability of Kelvin waves over the Congo basin from 1979 to 2010 are explored using outgoing longwave radiation (OLR) and National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis data. Composite method shows that high values of synoptic Kelvin wave (SKW) index are located over Congo basin during March-June where the convective active phase favors the formation of convective synoptic systems. Mean composite SKWs structure shows that these waves propagate faster over land surface and dissipate with suppressed phase. Because convective instability is smaller, these waves cannot grow in Congo basin. High correlation between SKWs and precipitation time series occurs when the Kelvin waves lead the precipitation time series by about 4 days. The analysis of 32 years datasets (1979–2010) also shows that in some particular year, strong SKWs propagation exists with periods centered around 5 days. Otherwise, results show marked inter-annual variability of Kelvin wave activity over Congo basin associated with divergence and low level westerly trade winds.


      PubDate: 2015-05-16T11:18:16Z
       
  • Observations of large-amplitude electromagnetic waves and associated
           wave–particle interactions at the dipolarization front in the
           Earth's magnetotail: A case study
    • Abstract: Publication date: July 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 129
      Author(s): S.Y. Huang , Z.G. Yuan , B. Ni , M. Zhou , H.S. Fu , S. Fu , X.H. Deng , Y. Pang , H.M. Li , D.D. Wang , H.M. Li , X.D. Yu
      Broadband frequency waves around the dipolarization front (DF) are believed to play a crucial role in the particle dynamics. Using the Cluster observations, we report in this study large-amplitude electromagnetic waves with frequencies just above the ion cyclotron frequency at the DF in the near-Earth magnetotail region. The waves have very large amplitudes of magnetic and electric field fluctuations, up to ~2nT and ~10mV/m, respectively. The magnetic fluctuations are predominately along the ambient magnetic field (B 0 ), while the electric fluctuations are primarily perpendicular to B 0 . The observed waves are highly oblique with a propagation angle of ~100° with respect to the ambient magnetic field, and are also linearly polarized. These features are consistent with the properties of the ion Bernstein wave mode in the high plasma β region, and also with the properties of current-driven ion cyclotron waves driven by the electromagnetic current-driven Alfven instability. We also discuss the possibility of wave–particle interactions at the DF.


      PubDate: 2015-05-16T11:18:16Z
       
  • Validating the use of scintillation proxies to study ionospheric
           scintillation over the Ugandan region
    • Abstract: Publication date: June 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 128
      Author(s): Emirant B. Amabayo , Edward Jurua , Pierre J. Cilliers
      In this study, we compare the standard scintillation indices (S 4 and σ Φ ) from a SCINDA receiver with scintillation proxies (S 4p and sDPR ) derived from two IGS GPS receivers. Amplitude (S 4) and phase ( σ Φ ) scintillation data were obtained from the SCINDA installed at Makerere University (0.34°N, 32.57°E). The corresponding amplitude (S 4p ) and phase ( sDPR ) scintillation proxies were derived from data archived by IGS GPS receivers installed at Entebbe (0.04°N, 32.44°E) and Mbarara (0.60°S, 30.74°E). The results show that for most of the cases analysed in this study, σ Φ and sDPR are in agreement. Amplitude scintillation occurrence estimated using the S 4p are fairly consistent with the standard S 4, mainly between 17:00 UT and 21:00 UT, despite a few cases of over and under estimation of scintillation levels by S 4p . Correlation coefficients between σ Φ and the sDPR proxy revealed positive correlation. Generally, S 4p and S 4 exhibits both moderate and strong positive correlation. TEC depletions associated with equatorial plasma bubbles are proposed as the cause of the observed scintillation over the region. These equatorial plasma bubbles were evident along the ray paths to satellites with PRN 2, 15, 27 and 11 as observed from MBAR and EBBE. In addition to equatorial plasma bubbles, atmospheric gravity waves with periods similar to those of large scale traveling ionospheric disturbances were also observed as one of the mechanisms for scintillation occurrence. The outcome of this study implies that GPS derived scintillation proxies can be used to quantify scintillation levels in the absence of standard scintillation data in the equatorial regions.


      PubDate: 2015-05-11T11:08:47Z
       
  • Extraction of the global absolute temperature for Northern Hemisphere
           using a set of 6190 meteorological stations from 1800 to 2013
    • Abstract: Publication date: June 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 128
      Author(s): Demetris T. Christopoulos
      Starting from a set of 6190 meteorological stations we are choosing 6130 of them and only for Northern Hemisphere we are computing average values for absolute annual Mean, Minimum, Q1, Median, Q3, Maximum temperature plus their standard deviations for years 1800–2013, while we use 4887 stations and 389467 rows of complete yearly data. The data quality and the seasonal bias indices are defined and used in order to evaluate our dataset. After the year 1969 the data quality is monotonically decreasing while the seasonal bias is positive in most of the cases. An Extreme Value Distribution estimation is performed for minimum and maximum values, giving some upper bounds for both of them and indicating a big magnitude for temperature changes. Finally suggestions for improving the quality of meteorological data are presented.
      Graphical abstract image Highlights

      PubDate: 2015-05-11T11:08:47Z
       
  • OI 630.0nm all-sky image observations of medium-scale traveling
           ionospheric disturbances at geomagnetic conjugate points
    • Abstract: Publication date: June 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 128
      Author(s): M.B. Stefanello , M.T.A.H. Muella , D.C.M. Amorim , C.S. Machado , J.V. Bageston , A.A. Pimenta , C. Martinis , C. Sullivan , J.A. Bittencourt , N.J. Schuch
      This paper presents a medium-scale traveling ionospheric disturbance (MSTID) occurrence detected through the OI 630.0nm emission all-sky images, obtained by ground-based imaging systems installed at close geomagnetic conjugate locations: one at the Southern Space Observatory-SSO/CRS/INPE-MCTI, (29.4°S, 53.8°W), in Sao Martinho da Serra, RS, Brazil, and another at the Arecibo Observatory (18.3°N, 66.7°W), in Puerto Rico. The images obtained show the optical signature of MSTIDs (low intensity regions of 630.0nm airglow emission), propagating simultaneously in both hemispheres, during geomagnetically quiet conditions (Kp<3). Observations using digital ionosonde installed at Falkland Islands (51.4°S, 57.5°W) and Ramey, Puerto Rico (18.5°N, 67.1°W) show an abrupt upward motion of the ionospheric F region plasma and the occurrence of frequency-type spread-F that could be related to the MSTIDs observed optically. Using Global Positioning System (GPS) receiver data, we also obtained the rate of the Total Electronic Content (TEC) change (ROT) for two geomagnetically conjugated sites-Santa Maria (29.7°S, 53.7°W) and Virgin Islands (17.7° N, 64.7°W). The analysis of TEC allows us to identify an irregular ionization in the F layer associated with the passage of an MSTID. The possible effects of the South America Magnetic Anomaly (SAMA) on the electrodynamic processes that control the inter-hemispheric coupling that give origin to the conjugate MSTIDs are highlighted and discussed.


      PubDate: 2015-05-11T11:08:47Z
       
  • Modelling the probability of ionospheric irregularity occurrence over
           African low latitude region
    • Abstract: Publication date: June 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 128
      Author(s): Patrick Mungufeni , Edward Jurua , John Bosco Habarulema , Simon Anguma Katrini
      This study presents models of geomagnetically quiet time probability of occurrence of ionospheric irregularities over the African low latitude region. GNSS-derived ionospheric total electron content data from Mbarara, Uganda (0.60°S, 30.74°E, geographic, 10.22°S, magnetic) and Libreville, Gabon (0.35°N, 9.68°E, geographic, 8.05°S, magnetic) during the period 2001–2012 were used. First, we established the rate of change of total electron content index (ROTI) value associated with background ionospheric irregularity over the region. This was done by analysing GNSS carrier-phases at L-band frequencies L1 and L2 with the aim of identifying cycle slip events associated with ionospheric irregularities. We identified at both stations a total of 699 events of cycle slips. The corresponding median ROTI value at the epochs of the cycle slip events was 0.54TECU/min. The probability of occurrence of ionospheric irregularities associated with ROTI ≥ 0.5 TECU / min was then modelled by fitting cubic B-splines to the data. The aspects the model captured included diurnal, seasonal, and solar flux dependence patterns of the probability of occurrence of ionospheric irregularities. The model developed over Mbarara was validated with data over Mt. Baker, Uganda (0.35°N, 29.90°E, geographic, 9.25°S, magnetic), Kigali, Rwanda (1.94°S, 30.09°E, geographic, 11.62°S, magnetic), and Kampala, Uganda (0.34°N, 32.60°E, geographic, 9.29°S, magnetic). For the period validated at Mt. Baker (approximately, 137.64km, north west), Kigali (approximately, 162.42km, south west), and Kampala (approximately, 237.61km, north east) the percentages of the number of errors (difference between the observed and the modelled probability of occurrence of ionospheric irregularity) less than 0.05 are 97.3, 89.4, and 81.3, respectively.


      PubDate: 2015-05-11T11:08:47Z
       
  • Latitude dependence of narrow bipolar pulse emissions
    • Abstract: Publication date: June 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 128
      Author(s): M.R. Ahmad , M.R.M. Esa , V. Cooray , Z.A. Baharudin , P. Hettiarachchi
      In this paper, we present a comparative study on the occurrence of narrow bipolar pulses (NBPs) and other forms of lightning flashes across various geographical areas ranging from northern regions to the tropics. As the latitude decreased from Uppsala, Sweden (59.8°N) to South Malaysia (1.5°N), the percentage of NBP emissions relative to the total number of lightning flashes increased significantly from 0.13% to 12%. Occurrences of positive NBPs were more common than negative NBPs at all observed latitudes. However, as latitudes decreased, the negative NBP emissions increased significantly from 20% (Uppsala, Sweden) to 45% (South Malaysia). Factors involving mixed-phase region elevations and vertical extents of thundercloud tops are invoked to explain the observed results. These factors are fundamentally latitude dependent. Our results suggest that the NBP emission rate is not a useful measure to monitor thunderstorm severity because regular tropical thunderstorms, where relatively high NBP emissions occur, lack suitable conditions to become severe (i.e., there is modest convective available potential energy and a lack of baroclinity in such regions). Observations of significantly high negative NBP occurrences together with very rare occurrences of positive cloud-to-ground flashes and isolated breakdown pulses in tropical thunderstorms are indicative of a stronger negative screening layer magnitude and weaker lower positive charge region magnitude than those in northern regions.


      PubDate: 2015-05-11T11:08:47Z
       
  • Effects of sporadic E-layer characteristics on spread-F generation in the
           nighttime ionosphere near a northern equatorial anomaly crest during solar
           minimum
    • Abstract: Publication date: June 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 128
      Author(s): C.C. Lee , W.S. Chen
      This study is to know how the characteristics of sporadic E-layer (Es-layer) affect the generation of spread-F in the nighttime ionosphere near the crest of equatorial ionization anomaly during solar minimum. The data of Es-layer parameters and spread-F are obtained from the Chungli ionograms of 1996. The Es-layer parameters include foEs (critical frequency of Es-layer), fbEs (blanketing frequency of Es-layer), and Δf (≡foEs−fbEs). Results show that the nighttime variations of foEs and fbEs medians (Δf medians) are different from (similar to) that of the occurrence probabilities of spread-F. Because the total number of Es-layer events is greater than that of spread-F events, the comparison between the medians of Es-layer parameters and the occurrence probabilities of spread-F might have a shortfall. Further, we categorize the Es-layer and spread-F events into each frequency interval of Es-layer parameters. For the occurrence probabilities of spread-F versus foEs, an increasing trend is found in post-midnight of all three seasons. The increasing trend also exists in pre-midnight of the J-months and in post-midnight of all seasons, for the occurrence probabilities of spread-F versus Δf. These demonstrate that the spread-F occurrence increases with increasing foEs and/or Δf. Moreover, the increasing trends indicate that polarization electric fields generated in Es-layer assist to produce spread-F, through the electrodynamical coupling of Es-layer and F-region. Regarding the occurrence probabilities of spread-F versus fbEs, the significant trend only appears in post-midnight of the E-months. This implies that fbEs might not be a major factor for the spread-F formation.


      PubDate: 2015-05-11T11:08:47Z
       
  • Long term changes in the ionosphere over Indian low latitudes: Impact of
           greenhouse gases
    • Abstract: Publication date: June 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 128
      Author(s): Som Sharma , H. Chandra , G. Beig
      Increased concentration of greenhouse gases due to anthropogenic activities warm the troposphere and have a cooling effect in the middle and upper atmosphere. Ionospheric densities and heights are affected due to cooling. Carbon dioxide is one of the most dominant gases for the cause of long term ionospheric trends along with other radiatively active greenhouse gases. Regular ionospheric soundings are made over Ahmedabad (23.1°N, 72.7°E), since 1953. Long term changes in the ionosphere as a consequence of the cooling of the mesosphere and thermosphere due to the increased concentration of greenhouse gases have been studied. Ionospheric observations over Ahmedabad, a low latitude station in the anomaly crest region, for the years 1955–2003 are examined to study the long term changes in the critical frequencies of the various ionospheric layers and the height of the maximum ionization as characterized by hPF2. A decrease in foF2 (1.9MHz for midday, 1.4MHz for midnight) and hPF2 (18km for midday, 17km for midnight) during about five decades are noted. An increase is noted in foF1 (0.4MHz). The foF2 data are also examined over an equatorial station Kodaikanal (10.2°N, 77.5°E), situated near the magnetic equator for the years 1960–1995 and a decrease of 0.5MHz for midday and 0.7MHz for midnight are noted in ~35 years.


      PubDate: 2015-05-11T11:08:47Z
       
  • Gravity wave characteristics in the middle atmosphere during the CESAR
           campaign at Palma de Mallorca in 2011/2012: Impact of extratropical
           cyclones and cold fronts
    • Abstract: Publication date: June 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 128
      Author(s): R. Kramer , S. Wüst , C. Schmidt , M. Bittner
      Based on a measuring campaign which was carried out at Mallorca (39.6°N, 2.7°E) as cooperation between Agència Estatal de Meteorologia (AEMET) and Deutsches Zentrum für Luft- und Raumfahrt, engl. 'German Aerospace Center' (DLR) in 2011/2012 (September–January), 143 radiosondes (day and night) providing vertical temperature and wind profiles were released. Additionally, nocturnal mesopause temperature measurements with a temporal resolution of about 1min were conducted by the infrared (IR) — Ground-based Infrared P-branch Spectrometer (GRIPS) during the campaign period. Strongly enhanced gravity wave activity in the lower stratosphere is observed which can be attributed to a hurricane-like storm (so-called Medicane) and to passing by cold fronts. Statistical features of gravity wave parameters including energy densitiy and momentum fluxes are calculated. Gravity wave momentum fluxes turned out being up to five times larger during severe weather. Moreover, gravity wave horizontal propagation characteristics are derived applying hodograph and Stokes parameter analysis. Preferred directions are of southeast and northwest due to prevailing wind directions at Mallorca.


      PubDate: 2015-05-11T11:08:47Z
       
  • IFC-Ed. board
    • Abstract: Publication date: June 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 128




      PubDate: 2015-05-11T11:08:47Z
       
  • Rain attenuation prediction during rain events in different climatic
           regions
    • Abstract: Publication date: June 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 128
      Author(s): Dalia Das , Animesh Maitra
      A rain attenuation prediction method has been applied to different climatic regions to test the validity of the model. The significant difference in rain rate and attenuation statistics for the tropical and temperate region needs to be considered in developing channel model to predict time series of rain attenuation for earth space communication links. Model parameters obtained for a tropical location has been successfully applied to predict time series of rain attenuation at other tropical locations. Separate model parameters are derived from the experimental data obtained at a temperate location and these are used to predict rain attenuation during rain events for other temperate locations showing the effectiveness of the technique.


      PubDate: 2015-05-11T11:08:47Z
       
  • Effect of diurnal variation of aerosols on surface reaching solar
           radiation
    • Abstract: Publication date: July 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 129
      Author(s): Kishore Reddy , D.V. Phanikumar , Hema Joshi , Y. Nazeer Ahammed , M. Naja
      In this report, we attempt to quantify direct aerosol radiative forcing by considering the diurnal variation of aerosols over central Himalayan region. The measured day time aerosol optical depth (AOD) values are higher by a small magnitude ≤15% during forenoon and reached as high as 90% by late afternoon when compare to night time AOD. The above observation gives clue about transport of regional polluted aerosols to the observational site. Our results show, 10 (16) % increment in atmospheric radiative forcing due to diurnal variation of aerosols instead of average aerosols during winter (post-monsoon) season.


      PubDate: 2015-05-11T11:08:47Z
       
  • Ionospheric anomalous disturbance during the tropospheric strong
           convective weather
    • Abstract: Publication date: July 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 129
      Author(s): Zhongya Cang , Guangguang Cheng , Guosheng Cheng
      Based on TBB data from Chinese FY-2 geostationary satellite, NCEP Reanalysis data and GPS-TEC data provided by IGS, by using sliding mean method, ionospheric anomalous disturbance during a typical convective weather was investigated. Results show that this severe convective weather was caused by a high-altitude cold eddy and a strong squall line. The ionospheric total electron content increased abnormally when convection occurred. The maximum increase of tested point was more than 6TECU mainly at 8–12 UT of the day, and the peak time of the day lagged about 2h than usual. Ionospheric anomalous region reached about 20 longitudes and 10 latitudes, and anomalous center was on the west side of the convective cloud, which may be related to the topographic effect of the Tibetan Plateau. Series of Case Studies further determine that convective weather can influence the ionospheric state. Furthermore, tropospheric vertical velocity was also analyzed to discuss the possible mechanisms of troposphere–ionosphere coupling.


      PubDate: 2015-05-11T11:08:47Z
       
  • Short term change in relative humidity during the festival of Diwali in
           India
    • Abstract: Publication date: July 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 129
      Author(s): Nandita D. Ganguly
      The changes in humidity levels during the Diwali festivities have been examined over a period of 13 years at three Indian metro cities: Ahmedabad, New Delhi and Kolkata. A small short term increase in relative humidity even in the absence of transport of humid air from Arabian Sea and Bay of Bengal has been observed. The relative humidity levels were found to be exceeding the ambient levels during night and lying below the ambient levels during morning hours, indicating an increase in the survival rates of viruses responsible for the transmission of viral infections, as well as triggering immune-mediated illnesses such as asthma during Diwali.


      PubDate: 2015-05-11T11:08:47Z
       
  • Automatic scaling of the sporadic E layer and removal of its multiple
           reflection and backscatter echoes for vertical incidence ionograms
    • Abstract: Publication date: July 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 129
      Author(s): Chunhua Jiang , Yuannong Zhang , Guobin Yang , Peng Zhu , Hengqing Sun , Xiao Cui , Huan Song , Zhengyu Zhao
      This paper presents a method for automatically scaling the sporadic E (Es) layer and removing its multiple reflection and backscatter echoes for vertical incidence (VI) ionograms. First, the method scales the Es layer automatically. Then, it removes the traces of multiple reflection and backscatter of the Es layer to clean VI ionograms using the parameters of the Es layer. Ionograms recorded at Wuhan (30.5°N, 114.37°E) are used to verify the performance of the proposed method compared with manually scaled values. The results indicate that the proposed method can automatically scale the Es layer and effectively improve the performance of the technique developed by Jiang et al. (2013).


      PubDate: 2015-05-11T11:08:47Z
       
  • A method to measure the broadband longwave irradiance in the terrestrial
           direct solar beam
    • Abstract: Publication date: July 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 129
      Author(s): Ibrahim Reda , Jörgen Konings , Yu Xie
      Shortwave radiometers such as pyranometers, pyrheliometers, photovoltaic cells, and longwave radiometers such as pyrgeometers are calibrated with traceability to consensus References, which are maintained by Absolute Cavity Radiometers (ACRs) and the World InfraRed Standard Group (WISG), respectively. Since the ACR is an open cavity with no window, and was developed to measure the extended broadband spectrum of the terrestrial direct solar beam irradiance, then there would be discrepancy in calibrating the shortwave radiometers because of their limited spectral band. On the other hand, pyrgeometers are calibrated during the nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This article describes a method to measure the broadband longwave irradiance in the terrestrial direct solar beam from 3µm to 50µm. The method might be used in developing calibration methods to address the mismatch between the broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometer calibration. We used the described method to measure the irradiance from sunrise to sunset; the irradiance varied from approximately 1Wm−2 to 16Wm−2 with an estimated uncertainty of 1.46Wm−2, for a solar zenith angle range from 80° to 16°, respectively.


      PubDate: 2015-05-11T11:08:47Z
       
  • Ionosphere equatorial ionization anomaly observed by GPS radio
           occultations during 2006–2014
    • Abstract: Publication date: July 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 129
      Author(s): Xinan Yue , William S. Schreiner , Ying-Hwa Kuo , Jiuhou Lei
      A large number of Global Position System (GPS) radio occultation (RO) observations have been accumulated in the University Corporation for Atmospheric Research (UCAR) Constellation Observation System for Meteorology, Ionosphere and Climate (COSMIC) Data Analysis and Archive Center (CDAAC) especially since the launch of COSMIC mission. This study made use of these RO data to study the morphology of ionosphere equatorial ionization anomaly (EIA) statistically during 2006–2014. The ionospheric peak density (NmF2) and peak height (hmF2) derived from the RO electron density profiles as well as the derived magnetic latitude of both crests and trough, the trough width, and the crest-to-trough ratio (CTR) of NmF2 are analyzed systematically. The corresponding seasonal, local time, and solar activity variations and the hemispheric asymmetry are identified and discussed. Most morphology agree well with previous studies and could be explained by the corresponding variations of neutral wind/composition and ExB vertical drift. We also found some interesting features. During May–August, magnetic latitude of the trough could be up to ~5° north of the equator especially around noontime, and the local time difference corresponding best developed EIA between both hemispheres could be up to ~6h. Both crests even move equator-ward with the increase of solar activity in the morning sector except June solstice.


      PubDate: 2015-05-11T11:08:47Z
       
  • An improved technique for global solar radiation estimation using
           numerical weather prediction
    • Abstract: Publication date: July 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 129
      Author(s): M.A. Shamim , R. Remesan , M. Bray , D. Han
      Global solar radiation is the driving force in hydrological cycle especially for evapotranspiration (ET) and is quite infrequently measured. This has led to the reliance on indirect techniques of estimation for data scarce regions. This study presents an improved technique that uses information from a numerical weather prediction (NWP) model (National Centre for Atmospheric Research NCAR's Mesoscale Meteorological model version 5 MM5), for the determination of a cloud cover index (CI), a major factor in the attenuation of the incident solar radiation. The cloud cover index (CI) together with the atmospheric transmission factor (K T ) and output from a global clear sky solar radiation were then used for the estimation of global solar radiation for the Brue catchment located in the southwest of England. The results clearly show an improvement in the estimated global solar radiation in comparison to the prevailing approaches.


      PubDate: 2015-05-11T11:08:47Z
       
  • Long-delayed bright dancing sprite with large Horizontal displacement from
           its parent flash
    • Abstract: Publication date: July 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 129
      Author(s): Jing Yang , Gaopeng Lu , Li-Jou Lee , Guili Feng
      We reported in this paper the observation of a very bright long-delayed dancing sprite with distinct horizontal displacement from its parent stroke. The dancing sprite lasted only 60ms, and the morphology consisted of three fields with two slim dim sprite elements in the first two fields and a very bright large element in the third field, different from other observations where the dancing sprites usually contained multiple elements over a longer time interval, and the sprite shape and brightness in the video field are often similar to the previous fields. The bright sprite was displaced at least 38km from its parent cloud-to-ground (CG) stroke and occurred over comparatively higher cloud top region. The parent flash of this compact dancing sprite was of positive polarity, with only one return stroke (approximately +24kA) and obvious continuing current process, and the charge moment change of stroke was small (barely above the threshold for sprite production). All the sprite elements occurred during the continuing current stage, and the bright long-delayed sprite element induced a considerable current pulse. The dancing feature of this sprite may be linked to the electrical charge structure, dynamics and microphysics of parent storm, and the inferred development of parent CG flash was consistent with previous very high-frequency (VHF) observations of lightning in the same region.


      PubDate: 2015-05-11T11:08:47Z
       
  • Extracting planetary waves from geomagnetic time series using Empirical
           Mode Decomposition
    • Abstract: Publication date: July 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 129
      Author(s): Dennis Frühauff , Karl-Heinz Glassmeier , Michael Lockwood , Daniel Heyner
      Empirical Mode Decomposition is presented as an alternative to traditional analysis methods to decompose geomagnetic time series into spectral components. Important comments on the algorithm and its variations will be given. Using this technique, planetary wave modes of 5-, 10-, and 16-day mean periods can be extracted from magnetic field components of three different stations in Germany. In a second step, the amplitude modulation functions of these wave modes can be shown to contain significant contribution from solar cycle variation through correlation with smoothed sunspot numbers. Additionally, the data indicate connections with geomagnetic jerk occurrences, supported by a second set of data providing reconstructed near-Earth magnetic field for 150 years. Usually attributed to internal dynamo processes within the Earth's outer core, the question of who is impacting whom will be briefly discussed here.


      PubDate: 2015-05-11T11:08:47Z
       
  • A tribute to Georg Witt
    • Abstract: Publication date: Available online 24 March 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Jörg Gumbel , Jacek Stegman



      PubDate: 2015-05-11T11:08:47Z
       
  • ATP4040: CO2 trapping in amorphous H2O ice: Relevance to polar mesospheric
           cloud particles
    • Abstract: Publication date: Available online 9 March 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): T.P. Mangan , V.L. Frankland , J.M.C. Plane
      Polar mesospheric clouds form in the summer high latitude mesopause region and are primarily comprised of H2O ice, forming at temperatures below 150K. Average summertime temperatures in the polar mesosphere (78°N) are approximately 125K and can be driven lower than 100K by gravity waves. Under these extreme temperature conditions and given the relative mesospheric concentrations of CO2 and H2O (~360ppmv and ~10ppmv, respectively) it has been hypothesised that CO2 molecules could become trapped within amorphous mesospheric ice particles, possibly making a significant contribution to the total condensed volume. Studies of CO2 trapping in co-deposited gas mixtures of increasing CO2:H2O ratio (deposited at 98K) were analysed via temperature programmed desorption. CO2 trapping was found to be negligible when the H2O flux to the surface was reduced to 4.8×1013 molecules cm−2 s−1. This corresponds to an average of 0.4 H2O molecules depositing on an adsorbed CO2 molecule and thereby trapping it in amorphous ice. Extrapolating the experimental data to mesospheric conditions shows that a mesospheric temperature of 100K would be required (at a maximum mesospheric H2O concentration of 10ppmv) in order to trap CO2 in the ice particles. Given the rarity of this temperature being reached in the mesosphere, this process would be an unlikely occurrence.


      PubDate: 2015-05-11T11:08:47Z
       
  • Layered phenomena in the mesopause region
    • Abstract: Publication date: Available online 23 April 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): J.M.C. Plane , S.M. Bailey , G. Baumgarten , M. Rapp



      PubDate: 2015-05-11T11:08:47Z
       
  • Investigating seasonal gravity wave activity in the summer polar
           mesosphere
    • Abstract: Publication date: Available online 4 April 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Y. Zhao , M.J. Taylor , C.E. Randall , J.D. Lumpe , D.E. Siskind , S.M. Bailey , J.M. Russell III
      The NASA Aeronomy of Ice in the Mesosphere (AIM) satellite is the first spaceborne mission dedicated to studying high-altitude (~83km) Polar Mesospheric Clouds (PMCs). Since its launch in 2007, the Cloud Imaging and Particle Size (CIPS) instrument onboard AIM has obtained large-field, high resolution (25km2/pixel) images of the PMCs, enabling a unique investigation of mesospheric gravity wave activity in the summer polar mesosphere where previous measurements have been sparse. In this study, we have analyzed 12 consecutive seasons of AIM/CIPS PMC albedo data to determine the statistical properties of medium and large horizontal scale (>100km) gravity waves present in the PMC data. Over 60,000 wave events with horizontal scale-sizes ranging up to >2000km have been identified and measured, revealing a wealth of wave events particularly in the ~300–800km range where our analysis sensitivity is largest. These data are ideal for investigating the intra-seasonal, inter-annual and hemispheric variability of these waves as observed over the whole summer polar cap regions. Throughout this 6 year study, the wave activity in the southern hemisphere was found to be consistently 10–15% higher than in the northern hemisphere and both the northern and southern hemisphere wave activity was determined to decrease systematically (by ~15%) during the course of each summer season. This decrease agrees well with previous seasonal stratospheric studies of variations in the wave energy, suggesting a direct influence of the lower atmospheric sources on polar mesospheric dynamics. Very similar and consistent results were also found from season to season in both hemispheres providing new information for gravity wave modeling and dynamical studies of the high-latitude summer-time mesosphere.


      PubDate: 2015-05-11T11:08:47Z
       
  • Summer time Fe depletion in the Antarctic mesopause region
    • Abstract: Publication date: Available online 28 April 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): T.P. Viehl , H. Höffner , F.-J. Lübken , J.M.C. Plane , B. Kaifler , R.J. Morris
      We report common volume measurements of Fe densities, temperatures and ice particle occurrence in the mesopause region at Davis Station, Antarctica (69°S) in the years 2011–2012. Our observations show a strong correlation of the Fe-layer summer time depletion with temperature, but no clear causal relation with the onset or occurrence of ice particles measured as noctilucent clouds (NLC) or polar mesosphere summer echoes (PMSE). The combination of these measurements indicates that the strong summer depletion can be explained by gas-phase chemistry alone and does not require heterogeneous removal of Fe and its compounds on ice particles.


      PubDate: 2015-05-11T11:08:47Z
       
  • Assessment of errors in precipitable water data derived from global
           navigation satellite system observations
    • Abstract: Publication date: Available online 25 April 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Pawel Hordyniec , Jaroslaw Bosy , Witold Rohm
      Among the new remote sensing techniques, one of the most promising is a GNSS meteorology, which provides continuous remote monitoring of the troposphere water vapor in all weather conditions with high temporal and spatial resolution. The Continuously Operating Reference Station (CORS) network and available meteorological instrumentation and models were scrutinized (we based our analysis on ASG-EUPOS network in Poland) as a troposphere Water Vapor retrieval system. This paper shows rigorous mathematical derivation of Precipitable Water errors based on uncertainties propagation method using all available data source quality measures (meteorological sensors and models precisions, ZTD estimation error, interpolation discrepancies, ZWD to PW conversion inaccuracies). We analyze both random and systematic errors introduced by indirect measurements and interpolation procedures, hence estimate the PW system integrity capabilities. The results for PW show that the systematic errors can be under half-millimeter level as long as pressure and temperature are measured at the observation site. In other case, i.e. no direct observations, Numerical Weather Model fields (we used in this study Coupled Ocean Atmospheric Mesoscale Prediction System) serves as the most accurate source of data. Investigated empirical pressure and temperature models, such as GPT2, GPT, UNB3m and Berg introduced into WV retrieval system, combined bias and random errors exceeding PW standard level of accuracy (3mm according to E-GVAP report). We also found that the pressure interpolation procedure is introducing over 0.5 hPa bias and 1 hPa standard deviation into the system (important in zenith total delay reduction) and hence has negative impact on the WV estimation quality.


      PubDate: 2015-05-11T11:08:47Z
       
  • Effect of recent minor volcanic Eruptions on Temperatures in the upper
           troposphere and lower stfratosphere
    • Abstract: Publication date: Available online 1 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Sanjay Kumar Mehta , Masatomo Fujiwara , Toshitaka Tsuda , Jean-Paul Vernier
      The impact of the recent minor volcanic eruptions during 2001–2010 in the temperature of the upper troposphere and lower stratosphere (UTLS) is investigated using data from the Global Positioning System Radio Occultation (GPS RO), three radiosonde compilations and two reanalyses (ERA-Interim and MERRA). The volcanic signals are identified in the residual temperature time series after removal of the linear trend, the quasi-biennial oscillation and El Nino Southern Oscillation components. Eight minor volcanic eruptions (six from the tropics and two from midlatitude) over the last decade (2001–2010) are analyzed in this study. We found significant volcanic signals in the UTLS temperature are found only in association with the tropical Soufrière Hills and Tavurvur eruptions (in May 2006 and in October 2006, respectively). Other four tropical eruptions had very small aerosol perturbations and did not show any significant UTLS temperature change. Out of the two midlatitude eruptions, Sarychev peak had similar stratospheric AOD perturbations as Soufrière Hills and Tavurvur eruptions, but it did not show any significant UTLS temperature change. The volcanic signals in the UTLS temperature from the tropical Soufrière Hills and Tavurvur eruptions were observed for the period of 7 months after August 2006. A warming of 0.5–0.8K in the tropical 16–18.5km (100–70hPa) layer was observed in association with these two tropical eruptions.


      PubDate: 2015-05-11T11:08:47Z
       
  • An analysis of selected aspects of irregularities oval monitoring using
           GNSS observations
    • Abstract: Publication date: Available online 1 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): R. Sieradzki
      The increasing number of permanent GNSS (Global Navigation Satellite System) receivers allows for more extensive ionospheric studies, involving the monitoring of the irregularities oval at high northern latitudes. Due to the high dynamics of the circumpolar ionosphere, the investigations aimed at a comprehensive view of oval should be carried out with as short a time resolution as possible. The shortening of this time interval leads to irregular coverage of the ionosphere by GNSS observations and has to be preceded by the preliminary analysis of selected aspects. Two of them are presented in this paper. The first one is the dependence of measured total electron content (TEC) fluctuations on the elevation angle of satellite observations. The results related to this point show its strong influence, clearly visible at low and high elevation angles. Furthermore, the additional impact of geomagnetic azimuth has been detected at lower elevation angles. The second analysed aspect is the comparative analysis of TEC fluctuation level changes observed in universal time and magnetic local time domains. Generally the study has confirmed the occurrence of oval variations, which can be monitored using subdaily maps of TEC fluctuations. The higher dynamics of ionospheric conditions have been observed in universal time domain, especially during the disturbed time. It indicates that the interpolation of TEC fluctuations values for regions without real data is more appropriate in magnetic local time domain.


      PubDate: 2015-05-11T11:08:47Z
       
  • Dynamically induced hemispheric differences in the seasonal cycle of the
           summer polar mesopause
    • Abstract: Publication date: Available online 5 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Erich Becker , Rahel Knöpfel , Franz-Josef Lübken
      A mechanistic atmospheric general circulation model from the surface up to the mesopause region with explicit representations of radiation and the tropospheric moisture cycle is employed to study hemispheric differences during the summer season with focus on dynamical coupling processes in the middle atmosphere. Hemispheric differences are imposed in the model by the geographical distributions of surface parameters. Consistent with reanalyses, we find that prior to summer solstice, the polar troposphere and lower stratosphere are significantly colder in the southern hemisphere than in the northern hemisphere. This induces vertically altering wind and temperature differences between the two hemispheres that are consistent with the recently detected Intrahemispheric Coupling mechanism. In particular, in the southern hemisphere the model yields a high mesopause around solstice which propagates downward over the season. Such a behavior has recently been observed by lidar measurements in Antarctica and is different from the northern hemisphere where the polar mesopause stays at approximately the same altitude over the summer season. After summer solstice, the mesopause is significantly warmer in the southern hemisphere, which is in accordance with Interhemispheric Coupling, i.e., the hemispheric differences after summer solstice are influenced by the strong planetary Rossby-wave activity in the northern stratosphere during boreal winter. Also enhanced filtering of eastward GWs in the southern troposphere contributes to the behavior after solstice. Orbital eccentricity is found to enhance the importance of Intrahemispheric Coupling. A more quantitative description of the hemispheric differences in the stratosphere and lower mesosphere as seen in reanalyses is obtained by adding an additional westward gravity drag in the southern stratosphere. The vertical mechanisms responsible for hemispheric differences apply also in this case.


      PubDate: 2015-05-11T11:08:47Z
       
  • Time evolution of ionization effect due to cosmic rays in terrestrial
           atmosphere during GLE 70
    • Abstract: Publication date: Available online 5 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): A.L. Mishev , P.I.Y. Velinov
      In the last years the possible effect of solar variability on atmospheric physics and chemistry is highly debated. In most of the proposed models the role of ion production in the atmosphere due to cosmic rays is significant. At resent are observed effects on minor constituents and aerosols over polar regions during major solar proton events. According to recent findings for a such effect it is necessary an essential increase of ion production, specifically during the winter season. Therefore, the ground level enhancement on 13th of December 2006 is appropriate for a such study. Here, we compute the ion production on 13th of December 2006 on the basis of a full target model based on Monte Carlo simulations. The ion production is computed on a step ranging from 10 to 30 minutes throughout the event. The spectral and angular characteristics of the solar protons are explicitly considered as well as their time evolution. The ionization effect is computed at several altitudes above the sea level, namely 25km, 18km, 15km, 12km and 8km in a sub-polar and polar regions, where the effect is maximal. Several applications of the obtained results are discussed.


      PubDate: 2015-05-11T11:08:47Z
       
  • Long-term variability of mid-latitude mesosphere-lower thermosphere winds
           over Collm (51°N, 13°E)
    • Abstract: Publication date: Available online 8 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Christoph Jacobi , Friederike Lilienthal , Christoph Geißler , Amelie Krug
      Radar observations of mesosphere/lower thermosphere (MLT) winds at middle latitudes obtained from meteor radar 2004-date and the low-frequency drift method 1979–2008 have been combined to obtain a homogeneous long-term data set of MLT dynamics at 90km altitude. The data are analyzed to obtain tendencies of prevailing winds during the last three decades. On a seasonal time scale, the zonal winds show positive trends towards more westerly winds throughout the year, while the meridional wind trends are negative in autumn/winter and positive in spring/summer. There is a tendency that the trends of both zonal and meridional summer prevailing winds are changing after 1995. Using a numerical circulation model with realistic ozone and carbon dioxide fields and with tropospheric/lower stratospheric circulation taken from ERA reanalyses, the observed trend changes can be reproduced qualitatively. The MLT wind trends are, according to the model, mainly due to the influence of changes in tropospheric and lower stratospheric dynamics.


      PubDate: 2015-05-11T11:08:47Z
       
  • Nonlinear dynamics of the 3D alfven waves in plasma of ionosphere and
           magnetosphere☆
    • Abstract: Publication date: Available online 8 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Vasily Yu. Belashov , Elena S. Belashova
      The nonlinear dynamics of the 3D solitary Alfvén waves propagating nearly parallel to the external magnetic field in plasma of ionosphere and magnetosphere, which are described by the model of the 3-DNLS equation, is studied analytically and numerically. Under the assumption of negligible dissipative effects the analytical estimates and the sufficient conditions for the stability of 3D solutions of the 3-DNLS equation are obtained, based on the transformational properties of the system's Hamiltonian for the whole range of the equation coefficients. On the basis of asymptotic analysis the solutions asymptotics are presented. To study the evolution of the 3D Alfven solitary waves including propagation of the Alfven waves’ beams in a magnetized plasma the equation are integrated numerically using the simulation codes specially developed. The results show that the 3-DNLS equation in non-dissipative case can have the stable 3D solutions in form of the 3D Alfvén solitons, and also on a level with them the 3D solutions collapsing or dispersing with time. In terms of the self-focusing phenomenon the results obtained can be interpreted as the formation of the stationary Alfvén wave beam propagating nearly parallel to magnetic field, or Alfvén wave beam spreading, or the self-focusing of the Alfvén wave beam. The influence of the dissipation in the medium on structure and character of evolution of 3D Alfvén waves is studied.


      PubDate: 2015-05-11T11:08:47Z
       
  • F region electron density profile inversion from backscatter ionogram
           based on international Reference ionosphere
    • Abstract: Publication date: Available online 8 May 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Peng Zhu , Chen Zhou , Yuannong Zhang , Guobin Yang , Chunhua Jiang , Hengqing Sun , Xiao Cui
      Ionospheric backscatter sounding transmits HF (3–30MHz) radio wave obliquely into ionosphere and receives echoes backscattered from remote ground. Due to the focusing effect, the echoes form leading edge on the swept frequency backscatter ionogram (BSI). This kind of backscatter ionogram contains plentiful ionospheric information, such as electron density, radio wave propagation modes and maximum usage frequency (MUF). By inversion algorithm, the backscatter ionogram can provide two-dimensional electron density profile (EDP) down range. In this paper, we propose an ionospheric F2 region EDP inversion algorithm. By utilizing the F2 bottomside electron density profile represented by the International Reference Ionosphere (IRI) model and ray tracing techniques, this approach inverts the leading edge of the backscatter ionogram to two dimensional F region EDP. Results of validation experiments demonstrate that the inverted ionospheric EDPs show good agreement with the results of vertical ionosonde and provide reliable information of ionosphere. Thus the proposed inversion algorithm provide an effective and accurate method for achieving large scale and remote ionospheric electron density structure.


      PubDate: 2015-05-11T11:08:47Z
       
  • Response to the comment on: “Soon, W., and Legates, D.R., solar
           irradiance modulation of equator-to-pole (Arctic) temperature gradients:
           empirical evidence for climate variation on multi-decadal timescales.
           Journal of Atmospheric and solar-terrestrial physics, 93, (2013)
           45–56” by F. Meunier and A. H. Reis
    • Abstract: Publication date: June 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 128
      Author(s): Willie Soon , David R. Legates
      We thank Meunier and Reis (hereafter as MR) for their comments on our paper. We, however, do not see the relevance of their alternative interpretation to our original results and believe this reflects their confusion regarding our conclusions rather than a discussion on physical mechanisms.


      PubDate: 2015-05-11T11:08:47Z
       
 
 
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