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Showing 1 - 36 of 36 Journals sorted alphabetically
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 36)
Advances in Climate Change Research     Open Access   (Followers: 12)
Advances in Meteorology     Open Access   (Followers: 19)
Advances in Statistical Climatology, Meteorology and Oceanography     Open Access   (Followers: 5)
Aeolian Research     Hybrid Journal   (Followers: 6)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 15)
American Journal of Climate Change     Open Access   (Followers: 16)
Atmósfera     Open Access   (Followers: 2)
Atmosphere     Open Access   (Followers: 20)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 12)
Atmospheric and Oceanic Science Letters     Open Access   (Followers: 4)
Atmospheric Chemistry and Physics (ACP)     Open Access   (Followers: 36)
Atmospheric Chemistry and Physics Discussions (ACPD)     Open Access   (Followers: 11)
Atmospheric Research     Hybrid Journal   (Followers: 61)
Atmospheric Science Letters     Open Access   (Followers: 30)
Boundary-Layer Meteorology     Hybrid Journal   (Followers: 26)
Bulletin of the American Meteorological Society     Open Access   (Followers: 39)
Carbon Balance and Management     Open Access   (Followers: 5)
Change and Adaptation in Socio-Ecological Systems     Open Access   (Followers: 2)
Climate     Open Access   (Followers: 3)
Climate Change Economics     Hybrid Journal   (Followers: 12)
Climate Change Responses     Open Access   (Followers: 4)
Climate Dynamics     Hybrid Journal   (Followers: 32)
Climate law     Hybrid Journal   (Followers: 3)
Climate of the Past (CP)     Open Access   (Followers: 3)
Climate of the Past Discussions (CPD)     Open Access  
Climate Policy     Hybrid Journal   (Followers: 29)
Climate Research     Hybrid Journal   (Followers: 6)
Climate Risk Management     Open Access   (Followers: 1)
Climate Services     Open Access  
Climate Summary of South Africa     Full-text available via subscription   (Followers: 1)
Climatic Change     Hybrid Journal   (Followers: 57)
Current Climate Change Reports     Hybrid Journal   (Followers: 3)
Developments in Atmospheric Science     Full-text available via subscription   (Followers: 21)
Dynamics and Statistics of the Climate System     Open Access   (Followers: 3)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 13)
Earth Perspectives - Transdisciplinarity Enabled     Open Access  
Energy & Environment     Hybrid Journal   (Followers: 21)
Environmental and Climate Technologies     Open Access   (Followers: 3)
Global Meteorology     Open Access   (Followers: 6)
International Journal of Atmospheric Sciences     Open Access   (Followers: 21)
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: 26)
International Journal of Image and Data Fusion     Hybrid Journal   (Followers: 2)
Journal of Applied Meteorology and Climatology     Full-text available via subscription   (Followers: 27)
Journal of Atmospheric and Oceanic Technology     Full-text available via subscription   (Followers: 31)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 140)
Journal of Atmospheric Chemistry     Hybrid Journal   (Followers: 21)
Journal of Climate     Full-text available via subscription   (Followers: 42)
Journal of Hydrology and Meteorology     Open Access   (Followers: 22)
Journal of Hydrometeorology     Full-text available via subscription   (Followers: 7)
Journal of Integrative Environmental Sciences     Hybrid Journal   (Followers: 4)
Journal of Meteorology and Climate Science     Full-text available via subscription   (Followers: 8)
Journal of Space Weather and Space Climate     Open Access   (Followers: 22)
Journal of the Atmospheric Sciences     Full-text available via subscription   (Followers: 68)
Journal of the Meteorological Society of Japan     Partially Free   (Followers: 3)
Journal of Weather Modification     Full-text available via subscription  
Large Marine Ecosystems     Full-text available via subscription   (Followers: 1)
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: 21)
Mètode Science Studies Journal : Annual Review     Open Access  
Michigan Journal of Sustainability     Open Access   (Followers: 1)
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 11)
Monthly Weather Review     Full-text available via subscription   (Followers: 28)
Nature Climate Change     Full-text available via subscription   (Followers: 73)
Nature Reports Climate Change     Full-text available via subscription   (Followers: 27)
npj Climate and Atmospheric Science     Open Access  
Open Journal of Modern Hydrology     Open Access   (Followers: 5)
Revista Brasileira de Meteorologia     Open Access  
Revista Iberoamericana de Bioeconomía y Cambio Climático     Open Access  
Russian Meteorology and Hydrology     Hybrid Journal   (Followers: 2)
Space Weather     Full-text available via subscription   (Followers: 20)
Studia Geophysica et Geodaetica     Hybrid Journal  
Tellus A     Open Access   (Followers: 21)
Tellus B     Open Access   (Followers: 19)
The Cryosphere (TC)     Open Access   (Followers: 4)
The Cryosphere Discussions (TCD)     Open Access   (Followers: 2)
The Quarterly Journal of the Royal Meteorological Society     Hybrid Journal   (Followers: 23)
Theoretical and Applied Climatology     Hybrid Journal   (Followers: 9)
Urban Climate     Hybrid Journal   (Followers: 1)
Weather     Hybrid Journal   (Followers: 15)
Weather and Climate Extremes     Open Access   (Followers: 10)
Weather and Forecasting     Full-text available via subscription   (Followers: 20)
Weatherwise     Hybrid Journal   (Followers: 4)
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]   [140 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1364-6826
   Published by Elsevier Homepage  [3175 journals]
  • Comparisons of planetary wave propagation to the upper atmosphere during
           stratospheric warming events at different QBO phases
    • Authors: Nikolai M. Gavrilov; Andrey V. Koval; Alexander I. Pogoreltsev; Elena N. Savenkova
      Pages: 1819 - 1836
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      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: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.asr.2017.08.022
      Issue No: Vol. 61, No. 7 (2018)
  • Source tracing of thunderstorm generated inertia-gravity waves observed
           during the RADAGAST campaign in Niamey, Niger
    • Authors: Kashyapa Naren Athreyas; Erry Gunawan; Bee Kiat Tay
      Pages: 1 - 9
      Abstract: Publication date: July 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 172
      Author(s): Kashyapa Naren Athreyas, Erry Gunawan, Bee Kiat Tay
      In recent years, the climate changes and weather have become a major concern which affects the daily life of a human being. Modelling and prediction of the complex atmospheric processes needs extensive theoretical studies and observational analyses to improve the accuracy of the prediction. The RADAGAST campaign was conducted by ARM climate research stationed at Niamey, Niger from January 2006 to January 2007, which was aimed to improve the west African climate studies have provided valuable data for research. In this paper, the characteristics and sources of inertia-gravity waves observed over Niamey during the campaign are investigated. The investigation focuses on highlighting the waves which are generated by thunderstorms which dominate the tropical region. The stratospheric energy densities spectrum is analysed for deriving the wave properties. The waves with Eulerian period from 20 to 50 h occupied most of the spectral power. It was found that the waves observed over Niamey had a dominant eastward propagation with horizontal wavelengths ranging from 350 to 1 400 km, and vertical wavelengths ranging from 0.9 to 3.6 km. GROGRAT model with ERA-Interim model data was used for establishing the background atmosphere to identify the source location of the waves. The waves generated by thunderstorms had propagation distances varying from 200 to 5 000 km and propagation duration from 2 to 4 days. The horizontal phase speeds varied from 2 to 20 m/s with wavelengths varying from 100 to 1 100 km, vertical phase speeds from 0.02 to 0.2 m/s and wavelengths from 2 to 15 km at the source point. The majority of sources were located in South Atlantic ocean and waves propagating towards northeast direction. This study demonstrated the complex large scale coupling in the atmosphere.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2018.03.003
      Issue No: Vol. 172 (2018)
  • Optical observations of electrical activity in cloud discharges
    • Authors: S.P.A. Vayanganie; M. Fernando; U. Sonnadara; V. Cooray; C. Perera
      Pages: 24 - 32
      Abstract: Publication date: July 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 172
      Author(s): S.P.A. Vayanganie, M. Fernando, U. Sonnadara, V. Cooray, C. Perera
      Temporal variation of the luminosity of seven natural cloud-to-cloud lightning channels were studied, and results were presented. They were recorded by using a high-speed video camera with the speed of 5000 fps (frames per second) and the pixel resolution of 512 × 512 in three locations in Sri Lanka in the tropics. Luminosity variation of the channel with time was obtained by analyzing the image sequences. Recorded video frames together with the luminosity variation were studied to understand the cloud discharge process. Image analysis techniques also used to understand the characteristics of channels. Cloud flashes show more luminosity variability than ground flashes. Most of the time it starts with a leader which do not have stepping process. Channel width and standard deviation of intensity variation across the channel for each cloud flashes was obtained. Brightness variation across the channel shows a Gaussian distribution. The average time duration of the cloud flashes which start with non stepped leader was 180.83 ms. Identified characteristics are matched with the existing models to understand the process of cloud flashes. The fact that cloud discharges are not confined to a single process have been further confirmed from this study. The observations show that cloud flash is a basic lightning discharge which transfers charge between two charge centers without using one specific mechanism.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2018.03.007
      Issue No: Vol. 172 (2018)
  • Response in the surface atmospheric electric field to the passage of
           isolated air mass cumulonimbus clouds
    • Authors: K.N. Pustovalov; P.M. Nagorskiy
      Pages: 33 - 39
      Abstract: Publication date: July 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 172
      Author(s): K.N. Pustovalov, P.M. Nagorskiy
      Convective clouds have a significant influence on the surface electric field. They are one of the most important components that support the global electrical circuit. To classify the response forms in the surface electric field to cumulonimbus clouds (Cb) at different stages of their development, the automated detection of the electric field response to the passage of isolated convective cells was carried out. The monitoring data of the surface electric field potential gradient (∇φ), registered in warm season over the period of 2006–2017 in Tomsk (south of Western Siberia), were used. In total, 9 types of ∇φ “slow variations” forms during the passage of isolated convective cells were identified. The main 6 types of ∇φ variations (97% of cases) were associated with different phases of the life cycle of the convective cell during its passage in the vicinity of the observation point. The main types of ∇φ variations were related to the Cb phases. Type 1 (12%) of ∇φ variations is unambiguously associated with cumulonimbus clouds in the growth phase and consists of one ∇φ disturbance with positive polarity. Type 2 (5%) of the ∇φ variations should be attributed to the “early” Cb mature stage, when there were shower, but without thunderstorm. Type 3 (19%) and type 4 (12% of ∇φ variations) can be associated with both “early” and “late” Cb mature phase. Type 5 (8% of ∇φ variations) should be associated with the “late” step of the Cb mature phase, when the intensity of the shower decreases and the intensity of the thunderstorm increases. Type 6 (41% of ∇φ variations) is a dominant one. It is associated with the Cb in the dissipation phase, when light shower and light thunderstorm are possible. These variations consist of one ∇φ disturbance of negative polarity. Thus, the general classification of response types in the electric field to the passage of isolated Cb in the vicinity of the observation point was suggested. It relates the types of ∇φ variations, the Cb development phases and the inclination peculiarities of its electric structure.
      Graphical abstract image

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2018.03.008
      Issue No: Vol. 172 (2018)
  • Relationship between lightning and solar activity for recorded between CE
           1392–1877 in Korea
    • Authors: Junhyeok Jeon; Sung-Jun Noh; Dong-Hee Lee
      Pages: 63 - 68
      Abstract: Publication date: July 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 172
      Author(s): Junhyeok Jeon, Sung-Jun Noh, Dong-Hee Lee
      In this study, we collected lightning data recorded in the Joseon-wangjo-sillok, one of the Korean history books, and discuss the characteristics of the long term variations and distribution of lightning based on the data. Although historical data such as lightning records are fragmentary, they are important information of solar activity on a long term scale. We found that there is a difference between the monthly distribution of lightning recorded in the Joseon-wangjo-sillok and the monthly distribution of modern observations. This difference of distribution could be understood to reflect that the purpose of viewpoint of the observers is different between the past and the present. Nevertheless, it is a very interesting result that the periodicity calculated from the records of lightning recorded in the Joseon-wangjo-sillok is similar to the solar cycle which is widely known as almost periodically 11 years.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2018.03.020
      Issue No: Vol. 172 (2018)
  • Wakefield acceleration in planetary atmospheres: A possible source of MeV
           electrons. The collisionless case
    • Authors: M. Arrayás; D. Cubero; J. Montanya; R. Seviour; J.L. Trueba
      Pages: 69 - 74
      Abstract: Publication date: July 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 172
      Author(s): M. Arrayás, D. Cubero, J. Montanya, R. Seviour, J.L. Trueba
      Intense electromagnetic pulses interacting with a plasma can create a wake of plasma oscillations. Electrons trapped in such oscillations can be accelerated under certain conditions to very high energies. We study the optimal conditions for the wakefield acceleration to produce MeV electrons in planetary plasmas under collisionless conditions. The conditions for the optimal plasma densities can be found in the Earth atmosphere at higher altitudes than 10–15 km, which are the altitudes where lightning leaders can take place.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2018.03.019
      Issue No: Vol. 172 (2018)
  • Ionospheric climatology at Africa EIA trough stations during descending
           phase of sunspot cycle 22
    • Authors: B.O. Adebesin; A.B. Rabiu; O.S. Bolaji; J.O. Adeniyi; C. Amory-Mazaudier
      Pages: 83 - 99
      Abstract: Publication date: July 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 172
      Author(s): B.O. Adebesin, A.B. Rabiu, O.S. Bolaji, J.O. Adeniyi, C. Amory-Mazaudier
      The African equatorial ionospheric climatology during the descending phase of sunspot-cycle 22 (spanning 1992–1996) was investigated using 3 ionosondes located at Dakar (14.70 N, 342.60 E), Ouagadougou (12.420 N, 358.60 E), and Korhogo (9.510 N, 354.40 E). The variations in the virtual height of the F-layer (h’F), maximum electron density (NmF2), vertical plasma drift (Vp) and zonal electric field (Ey) were presented. Significant decrease in the NmF2 amplitude compared to h’F in all of the stations during the descending period is obvious. While NmF2 magnitude maximizes/minimizes during the E-seasons/J-season, h’F attained highest/lowest altitude in J-season/D-season for all stations. D-season anomaly was evident in NmF2 at all stations. For any season, the intensity (I bt ) of NmF2 noon-bite-out is highest at Dakar owning to fountain effect and maximizes in March-E season. Stations across the EIA trough show nearly coherence ionospheric climatology characteristics whose difference is of latitudinal origin. Hemispheric dependence in NmF2 is obvious, with difference more significant during high-solar activity and closes with decreasing solar activity. The variability in the plasma drift during the entire phase is suggested to emanate from solar flux variations, and additionally from enhanced leakage of electric fields from high-to low-latitudes. Existing African regional model of evening/nightttime pre-reversal plasma drift/sunspot number (PRE peak /R) relationship compares well with experimental observations at all stations with slight over-estimation. The correlation/root-mean-square-deviation (RMS dev ) pair between the model and observed Vp during the descending phase recorded 94.9%/0.756, 92.4%/1.526, and 79.1%/3.612 at Korhogo, Ouagadougou and Dakar respectively. The Ey/h’F and Ey/NmF2 relationships suggest that zonal electric field is more active in the lifting of h’F and suppression of NmF2 during high- and moderate-solar activities when compared with low-solar activity. This is the first work to show higher bite-out at the equatorial northern-station (Dakar) than southern-station (Korhogo) using ionosonde data.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2018.03.009
      Issue No: Vol. 172 (2018)
  • Propagation of non-stationary acoustic-gravity waves at thermospheric
           temperatures corresponding to different solar activity
    • Authors: N.M. Gavrilov; S.P. Kshevetskii; A.V. Koval
      Pages: 100 - 106
      Abstract: Publication date: July 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 172
      Author(s): N.M. Gavrilov, S.P. Kshevetskii, A.V. Koval
      Numerical simulation of non-stationary nonlinear acoustic-gravity waves (AGWs) propagating from the surface wave source to the thermosphere reveals that their propagation conditions and parameters depend on changes in background temperature, density, composition, molecular viscosity and heat conduction caused by changes in solar activity (SA). At small wave source amplitudes, AGW amplitudes, momentum fluxes and wave accelerations of the mean flow are slightly larger at altitudes about 150 km at low SA because of smaller mean density and ρ 0 − 1 / 2 dependence of wave amplitudes at low dissipation. Larger kinematic coefficients of molecular viscosity and heat conduction lead to stronger decrease of wave amplitudes and momentum fluxes at altitudes above 150 km at low SA. At large amplitudes of surface wave excitation, AGW breaking and smaller-scale inhomogeneities appear at altitudes 100–150 km, which are stronger at low SA. Increased dissipation of breaking AGWs may produce wave-induced jet streams with velocities close to the wave horizontal phase speed and near-critical layers at altitudes 110–150 km, which dramatically decrease amplitudes and momentum fluxes of the primary AGW mode propagating from the surface wave source. The wave-induced horizontal wind becomes smaller above altitude of 150 km and allows growing amplitudes of the primary wave mode partially penetrating through the near-critical layer and of secondary AGW modes, possibly generating in the wave induced jet stream. The wave amplitude grows at altitudes higher than 150 km is larger at high SA due to smaller velocities of wave-induced mean wind and smaller molecular viscosity and heat conduction. Accelerations of the mean flow by dissipating AGWs are generally larger at low SA. This determines faster grows of wave-induced jet streams in time at low SA. In almost all simulated cases, velocities of the wave-induced mean flows are higher at low SA compared to high SA. Resulting SA impact at a given thermospheric altitude depends on competition between AGW amplitude increase due to smaller molecular dissipation and smaller energy transfer to the wind-induced mean flow and amplitude decrease caused by larger density and stronger reflection at higher SA.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2018.03.021
      Issue No: Vol. 172 (2018)
  • Is there a conclusive evidence on lightning-related effects on sporadic E
    • Authors: Christos Haldoupis
      Pages: 117 - 121
      Abstract: Publication date: July 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 172
      Author(s): Christos Haldoupis
      In recent years, there have been a few studies claiming that thunderstorm cloud-to-ground lightning discharges affect sporadic E layers existing over the storm. In this brief paper, we consider and critically evaluate the results of these studies in the context of our present knowledge on sporadic E layers and the coupling processes of thunderstorm and lightning wave energy into the upper atmosphere and lower ionosphere. It is shown that the reported findings and their implications raise questions and cast doubts, therefore the conclusions of the existing studies are not substantiated and thus need to be treated with caution. We reason that, the anticipated occurrence of lighting-related effects on midlatitude sporadic E lacks at present firm verification.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2018.03.024
      Issue No: Vol. 172 (2018)
  • A new method for reconstruction of solar irradiance
    • Authors: Victor Privalsky
      Pages: 138 - 142
      Abstract: Publication date: July 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 172
      Author(s): Victor Privalsky
      The purpose of this research is to show how time series should be reconstructed using an example with the data on total solar irradiation (TSI) of the Earth and on sunspot numbers (SSN) since 1749. The traditional approach through regression equation(s) is designed for time-invariant vectors of random variables and is not applicable to time series, which present random functions of time. The autoregressive reconstruction (ARR) method suggested here requires fitting a multivariate stochastic difference equation to the target/proxy time series. The reconstruction is done through the scalar equation for the target time series with the white noise term excluded. The time series approach is shown to provide a better reconstruction of TSI than the correlation/regression method. A reconstruction criterion is introduced which allows one to define in advance the achievable level of success in the reconstruction. The conclusion is that time series, including the total solar irradiance, cannot be reconstructed properly if the data are not treated as sample records of random processes and analyzed in both time and frequency domains.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2018.04.001
      Issue No: Vol. 172 (2018)
  • Recent developments in the understanding of equatorial ionization anomaly:
           A review
    • Authors: N. Balan; J. Souza; G.J. Bailey
      Pages: 3 - 11
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): N. Balan, J. Souza, G.J. Bailey
      A brief review of the recent developments in the understanding of the equatorial plasma fountain (EPF) and equatorial ionization anomaly (EIA) under quiet and active conditions is presented. It is clarified that (1) the EPF is not upward ExB plasma drift at the equator followed by downward plasma diffusion, but it is field perpendicular ExB plasma drift and field-aligned plasma diffusion acting together all along the field lines at all altitudes and plasma flowing in the direction of the resultant. (2) The EIA is formed not from the accumulation of plasma at the crests but mainly from the removal of plasma from around the equator by the upward ExB drift with small accumulations when the crests are within approximately ±20° magnetic latitude. The accumulations reduce with increasing latitude and become zero by approximately ±25°. (3) An asymmetric neutral wind makes EPF and EIA asymmetric with stronger fountain and stronger crest usually occurring in opposite hemispheres especially at equinoxes when winter anomaly is absent. (4) During the early stages of daytime main phase of major geomagnetic storms, the plasma fountain becomes a super fountain and the EIA becomes strong not due to the eastward prompt penetration electric field (PPEF) alone but due to the combined effect of eastward PPEF and storm-time equatorward winds (SEW). (5) During the later stages of the storms when EIA gets inhibited a peak sometimes occurs around the equator not due to westward electric fields but mainly due to the convergence of plasma from both hemispheres due to SEW.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.06.020
      Issue No: Vol. 171 (2018)
  • Temperature properties in the tropical tropopause layer and their
           correlations with Outgoing Longwave Radiation: FORMOSAT-3/COSMIC
    • Authors: Kaiti Wang; Yi-chao Wu; Jia-Ting Lin; Pei-Hua Tan
      Pages: 21 - 35
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): Kaiti Wang, Yi-chao Wu, Jia-Ting Lin, Pei-Hua Tan
      The properties of temperature at the level of lapse rate minimum (LRM) in the tropical tropopause layer between 20°S and 20°N are investigated using 3-year radio occultation observations based on the FORMOSAT-3/COSMIC mission from November of 2006 to October of 2009. The correlations between this LRM temperature and Outgoing Longwave Radiation (OLR) are analyzed by 5° × 5° grids in longitude and latitude. Two primary regions, one from 60°E to 180°E and the other from 90°W to 30°E, are found to have higher correlations and can be associated with regions of lower OLR values. The patterns of this spatial distributions of regions with higher correlations begin to change more obviously when the altitude ascends to the level of Cold Point Tropopause (CPT). This correlation at the LRM altitude in annual and seasonal scales also shows spatial distributions associated with OLR intensities. The altitudinal dependence of the correlations between temperature and OLR is further analyzed based on grids of high correlations with significance at LRM altitude, for the two primary regions. The results show that for the different time scales in this analysis (3-year, annual, and seasonal), the correlations all gradually decrease above the LRM levels but maintain a significant level to as high as 2.5–3.5 km. Below the LRM level, the correlation decreases with a slower rate as the altitude descends and still keeps significant at the deep 5 km level. These suggest that the vertical temperature profiles could be affected by the convection mechanism for a wide range of altitudes in the troposphere even above LRM altitude. Applying the same analysis on one complete La Niña event during the survey period also reveals similar features.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.07.012
      Issue No: Vol. 171 (2018)
  • Estimation of ionospheric sporadic E intensities from GPS radio
           occultation measurements
    • Authors: C. Arras; J. Wickert
      Pages: 60 - 63
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): C. Arras, J. Wickert
      The radio occultation experiment aboard the FORMOSAT-3/COSMIC satellites enables the observation of phenomena in Earth's ionosphere on a global scale. Numerous radio occultation profiles are used to analyse the occurrence of sporadic E layers as well as its properties. We will present a new method to approach additionally to the presence of sporadic E also its intensity which is closely related to the blanketing frequency ( f b E s ) provided by ionosondes. We observed that the sporadic E occurrence and its intensity show a highly developed annual cycle with high occurrence rates and intensities in the actual summer hemisphere. The global latitude/longitude distribution of both parameters is strongly related to Earth's magnetic field which is reflected by the missing of sporadic E observations along the magnetic equator.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.08.006
      Issue No: Vol. 171 (2018)
  • The influence of tidal winds in the formation of blanketing sporadic
           e-layer over equatorial Brazilian region
    • Authors: Laysa Cristina Araujo Resende; Inez Staciarini Batista; Clezio Marcos Denardini; Paulo Prado Batista; Alexander José Carrasco; Vânia Fátima Andrioli; Juliano Moro
      Pages: 64 - 71
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): Laysa Cristina Araujo Resende, Inez Staciarini Batista, Clezio Marcos Denardini, Paulo Prado Batista, Alexander José Carrasco, Vânia Fátima Andrioli, Juliano Moro
      This work analysis the blanketing sporadic layers (Esb) behavior over São Luís, Brazil (2° 31′ S, 44° 16′ W, dip: −4.80) which is classified as a transition region between equatorial and low-latitude. Hence, some peculiarities can appear as Esb occurrence instead of the common Esq, which is a non-blanketing irregularity layer. The analysis presented here was obtained using a modified version of a theoretical model for the E region (MIRE), which computes the densities of the metallic ions (Fe+ and Mg+) and the densities of the main molecular ions (NO+, O2 +, N2 +) by solving the continuity and momentum equations for each one of them. In that model, the Es layer physics driven by both diurnal and semidiurnal tidal winds are taken into account and it was extended in height coverage by adding a novel neutral wind model derived from the all-sky meteor radar measurements. Thus, we provide more trustworthy results related to the Es layer formation in the equatorial region. We verified the contribution of each tidal wind component to the Esb layer formation in this equatorial region. Additionally, we compared the Es layer electron density computed by MIRE with the data obtained by using the blanketing frequency parameter (fbEs) deduced from ionograms. The results show that the diurnal component of the tidal wind is more important in the Esb layer formation whereas the semidiurnal component has a little contribution in our simulations. Finally, it was verified that the modified MIRE presented here can be used to study the Esb layers occurrence over the equatorial region in the Brazilian sector.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.06.009
      Issue No: Vol. 171 (2018)
  • Aerosols and seismo-ionosphere coupling: A review
    • Authors: Aleksandr Namgaladze; Mikhail Karpov; Maria Knyazeva
      Pages: 83 - 93
      Abstract: Publication date: Available online 14 February 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Aleksandr Namgaladze, Mikhail Karpov, Maria Knyazeva
      The role of atmosphere aerosols in the global electric circuit, particularly during earthquakes preparation periods, is discussed in this review paper. Aerosols participate in production and transport of electric charges as well as in clouds formation. Satellite imagery shows increased aerosol optical depth over the tectonic faults and formation of the anomalous clouds aligned with the faults shortly before the earthquake shocks. At the same time variations of the ionospheric electric field and total electron content (TEC) are observed. We assume that the vertical electric current is generated over the fault due to the separation and vertical transport of charges with different masses and polarities. This charges the ionosphere positively relative to the Earth in the same way as the thunderstorm currents do. The resulting electric field in the ionosphere drives F2-layer plasma via the electromagnetic [ E → × B → ] drift and decreases or increases electron density depending on the configuration of the electric field, thus, creating observed negative or positive TEC disturbances. The important role of the electric dynamo effect in these processes is underlined.

      PubDate: 2018-02-26T14:37:17Z
      DOI: 10.1016/j.jastp.2018.01.014
      Issue No: Vol. 171 (2018)
  • The zonal-mean and regional tropospheric pressure responses to changes in
           ionospheric potential
    • Authors: Limin Zhou; Brian Tinsley; Lin Wang; Gary Burns
      Pages: 111 - 118
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): Limin Zhou, Brian Tinsley, Lin Wang, Gary Burns
      Global reanalysis data reveal daily surface pressure responses to changes in the global ionospheric potential in both polar and sub-polar regions. We use 21 years of data to show that the pressure response to externally-induced ionospheric potential changes, that are due to the interplanetary magnetic field east-west (IMF B y ) component, are present in two separate decadal intervals, and follow the opposite ionospheric potential changes in the Arctic and Antarctic for a given B y . We use the 4 years of available data to show that the pressure responses to changes in internally generated ionospheric potential, that are caused by low-latitude thunderstorms and highly electrified clouds, agree in sign and sensitivity with those externally generated. We have determined that the daily varying pressure responses are stronger in local winter and spring. The pressure responses at polar latitudes are predominantly over the Antarctic and Greenland ice caps, and those at sub-polar latitudes are of opposite sign, mainly over oceans. A lead-lag analysis confirms that the responses maximize within two days of the ionospheric potential input. Regions of surface pressure fluctuating by about 4 hPa in winter are found with ionospheric potential changes of about 40 kV. The consistent pressure response to the independent external and internal inputs strongly supports the reality of a cloud microphysical mechanism affected by the global electric circuit. A speculative mechanism involves the ionosphere-earth current density J z , which produces space charge at cloud boundaries and electrically charged droplets and aerosol particles. Ultrafine aerosol particles, under the action of electro-anti-scavenging, are enabled to grow to condensation nuclei size, affecting cloud microphysics and cloud opacity and surface pressure on time scales of hours.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.07.010
      Issue No: Vol. 171 (2018)
  • Modeling study of the ionospheric responses to the quasi-biennial
           oscillations of the sun and stratosphere
    • Authors: Jack C. Wang; Rong Tsai-Lin; Loren C. Chang; Qian Wu; Charles C.H. Lin; Jia Yue
      Pages: 119 - 130
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): Jack C. Wang, Rong Tsai-Lin, Loren C. Chang, Qian Wu, Charles C.H. Lin, Jia Yue
      The Quasi-biennial Oscillation (QBO) is a persistent oscillation in the zonal mean zonal winds of the low latitude middle atmosphere that is driven by breaking planetary and gravity waves with a period near two years. The atmospheric tides that dominate the dynamics of the mesosphere and lower thermosphere region (MLT, between heights of 70–120 km) are excited in the troposphere and stratosphere, and propagate through QBO-modulated zonal mean zonal wind fields. This allows the MLT tidal response to also be modulated by the QBO, with implications for ionospheric/thermospheric variability. Interannual oscillations in solar radiation can also directly drive the variations in the ionosphere with similar periodicities through the photoionization. Many studies have observed the connection between the solar activity and QBO signal in ionospheric features such as total electron content (TEC). In this research, we develop an empirical model to isolate stratospheric QBO-related tidal variability in the MLT diurnal and semidiurnal tides using values from assimilated TIMED satellite data. Migrating tidal fields corresponding to stratospheric QBO eastward and westward phases, as well as with the quasi-biennial variations in solar activity isolated by the Multi-dimensional Ensemble Empirical Mode Decomposition (MEEMD) analysis from Hilbert-Huang Transform (HHT), are then used to drive the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). The numerical experiment results indicate that the ionospheric QBO is mainly driven by the solar quasi-biennial variations during the solar maximum, since the solar quasi-biennial variation amplitude is directly proportionate to the solar cycle. The ionospheric QBO in the model is sensitive to both the stratospheric QBO and solar quasi-biennial variations during the solar minimum, with solar effects still playing a stronger role.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.07.024
      Issue No: Vol. 171 (2018)
  • Ionosonde-based indices for improved representation of solar cycle
           variation in the International Reference Ionosphere model
    • Authors: Steven Brown; Dieter Bilitza; Erdal Yiğit
      Pages: 137 - 146
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): Steven Brown, Dieter Bilitza, Erdal Yiğit
      A new monthly ionospheric index, IG NS , is presented to improve the representation of the solar cycle variation of the ionospheric F2 peak plasma frequency, foF2. IG NS is calculated using a methodology similar to the construction of the ”global effective sunspot number”, IG, given by Liu et al. (1983) but selects ionosonde observations based on hemispheres. We incorporated the updated index into the International Reference Ionosphere (IRI) model and compared the foF2 model predictions with global ionospheric observations. We also investigated the influence of the underlying foF2 model on the IG index. IRI has two options for foF2 specification, the CCIR-66 and URSI-88 foF2 models. For the first time, we have calculated IG using URSI-88 and assessed the impact on model predictions. Through a retrospective model-data comparison, results show that the inclusion of the new monthly IG NS index in place of the current 12-month smoothed IG index reduce the foF2 model prediction errors by nearly a factor of two. These results apply to both day-time and nightime predictions. This is due to an overall improved prediction of foF2 seasonal and solar cycle variations in the different hemispheres.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.08.022
      Issue No: Vol. 171 (2018)
  • Solar signals detected within neutral atmospheric and ionospheric
    • Authors: Petra Koucka Knizova; Katya Georgieva; Zbysek Mosna; Michal Kozubek; Daniel Kouba; Boian Kirov; Katerina Potuzníkova; Josef Boska
      Pages: 147 - 156
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): Petra Koucka Knizova, Katya Georgieva, Zbysek Mosna, Michal Kozubek, Daniel Kouba, Boian Kirov, Katerina Potuzníkova, Josef Boska
      We have analyzed time series of solar data together with the atmospheric and ionospheric measurements for solar cycles 19 till 23 according to particular data availability. For the analyses we have used long term data with 1-day sampling. By mean of Continuous Wavelet Transform (CWT) we have found common spectral domains within solar and atmospheric and ionospheric time series. Further we have identified terms when particular pairs of signals show high coherence applying Wavelet Transform Coherence (WTC). Despite wide oscillation ranges detected in particular time series CWT spectra we found only limited domains with high coherence by mean of WTC. Wavelet Transform Coherence reveals significant high power domains with stable phase difference for periods 1 month, 2 months, 6 months, 1 year, 2 years and 3–4 years between pairs of solar data and atmospheric and ionospheric data. The occurence of the detected domains vary significantly during particular solar cycle (SC) and from cycle to the following one. It indicates the changing solar forcing and/or atmospheric sensitivity with time.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.12.003
      Issue No: Vol. 171 (2018)
  • Kelvin wave coupling from TIMED and GOCE: Inter/intra-annual variability
           and solar activity effects
    • Authors: Federico Gasperini; Jeffrey M. Forbes; Eelco N. Doornbos; Sean L. Bruinsma
      Pages: 176 - 187
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): Federico Gasperini, Jeffrey M. Forbes, Eelco N. Doornbos, Sean L. Bruinsma
      The primary mechanism through which energy and momentum are transferred from the lower atmosphere to the thermosphere is through the generation and propagation of atmospheric waves. It is becoming increasingly evident that a few waves from the tropical wave spectrum preferentially propagate into the thermosphere and contribute to modify satellite drag. Two of the more prominent and well-established tropical waves are Kelvin waves: the eastward-propagating 3-day ultra-fast Kelvin wave (UFKW) and the eastward-propagating diurnal tide with zonal wave number 3 (DE3). In this work, Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperatures at 110 km and Gravity field and steady-state Ocean Circulation Explorer (GOCE) neutral densities and cross-track winds near 260 km are used to demonstrate vertical coupling in this height regime due to the UFKW and DE3. Significant inter- and intra-annual variability is found in DE3 and the UFKW, with evidence of latitudinal broadening and filtering of the latitude structures with height due to the effect of dissipation and mean winds. Additionally, anti-correlation between the vertical penetration of these waves to the middle thermosphere and solar activity level is established and explained through the effect of molecular dissipation.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.08.034
      Issue No: Vol. 171 (2018)
  • Impact of non-migrating tides on the low latitude ionosphere during a
           sudden stratospheric warming event in January 2010
    • Authors: S.E. McDonald; F. Sassi; J. Tate; J. McCormack; D.D. Kuhl; D.P. Drob; C. Metzler; A.J. Mannucci
      Pages: 188 - 200
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): S.E. McDonald, F. Sassi, J. Tate, J. McCormack, D.D. Kuhl, D.P. Drob, C. Metzler, A.J. Mannucci
      The lower atmosphere contributes significantly to the day-to-day variability of the ionosphere, especially during solar minimum conditions. Ionosphere/atmosphere model simulations that incorporate meteorology from data assimilation analysis products can be critically important for elucidating the physical processes that have substantial impact on ionospheric weather. In this study, the NCAR Whole Atmosphere Community Climate Model, extended version with specified dynamics (SD-WACCM-X) is coupled with an ionospheric model (Sami3 is Another Model of the Ionosphere) to study day-to-day variability in the ionosphere during January 2010. Lower atmospheric weather patterns are introduced into the SAMI3/SD-WACCM-X simulations using the 6-h Navy Operational Global Atmospheric Prediction System-Advanced Level Physics High Altitude (NOGAPS-ALPHA) data assimilation products. The same time period is simulated using the new atmospheric forecast model, the High Altitude Navy Global Environmental Model (HA-NAVGEM), a hybrid 4D-Var prototype data assimilation with the ability to produce meteorological fields at a 3-h cadence. Our study shows that forcing SD-WACCM-X with HA-NAVGEM better resolves the semidiurnal tides and introduces more day-to-day variability into the ionosphere than forcing with NOGAPS-ALPHA. The SAMI3/SD-WACCM-X/HA-NAVGEM simulation also more accurately captures the longitudinal variability associated with non-migrating tides in the equatorial ionization anomaly (EIA) region as compared to total electron content (TEC) maps derived from GPS data. Both the TEC maps and the SAMI3/SD-WACCM-X/HA-NAVGEM simulation show an enhancement in TEC over South America during 17–21 January 2010, which coincides with the commencement of a stratospheric warming event on 19 January 2010. Analysis of the SAMI3/SD-WACCM-X/HA-NAVGEM simulations indicates non-migrating tides (including DW4, DE2 and SW5) played a role during 17–21 January in shifting the phase of the wave-3 pattern in the ionosphere on these days. Constructive interference of wave-3 and wave-4 patterns in the E × B drifts contributed to the enhanced TEC in the South American longitude sector. The results of the study highlight the importance of high fidelity meteorology in understanding the day-to-day variability of the ionosphere.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.09.012
      Issue No: Vol. 171 (2018)
  • Planetary wave-like oscillations in the ionosphere retrieved with a
           longitudinal chain of ionosondes at high northern latitudes
    • Authors: Nora H. Stray; Patrick J. Espy
      Pages: 225 - 233
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): Nora H. Stray, Patrick J. Espy
      This paper examines the influence of neutral dynamics on the high latitude ionosphere. Using a longitudinal chain of ionosondes at high northern latitudes (52°–65° N), planetary wave-like structures were observed in the spatial structure of the peak electron density in the ionosphere. Longitudinal wavenumbers S0, S1 and S2 have been extracted from these variations of the F layer. The observed wave activity in wavenumber one and two does not show any significant correlation with indices of magnetic activity, suggesting that this is not the primary driver. In addition, the motion of the S1 ionospheric wave structures parallels that of the S1 planetary waves observed in the winds of the mesosphere-lower-thermosphere derived from a longitudinal array of SuperDARN meteor-radar wind measurements. The time delay between the motions of the wave structures would indicate a indirect coupling, commensurate with the diffusion to the ionosphere of mesospheric atomic oxygen perturbations.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.10.011
      Issue No: Vol. 171 (2018)
  • On the importance of an atmospheric reference model: A case study on
           gravity wave-airglow interactions
    • Authors: Yolián Amaro-Rivera; Tai-Yin Huang; Julio Urbina
      Pages: 260 - 268
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): Yolián Amaro-Rivera, Tai-Yin Huang, Julio Urbina
      The atmospheric reference model utilized in an airglow numerical study is important since airglow emissions depend on the number density of the light-emitting species. In this study, we employ 2-dimensional, nonlinear, time-dependent numerical models, Multiple Airglow Chemistry Dynamics (MACD) and OH Chemistry Dynamics (OHCD), that use the MSISE-90, NRLMSISE-00, and Garcia and Solomon (GS) model data as atmospheric reference models, to investigate gravity wave-induced airglow variations for the OH(8,3) airglow, O2(0,1) atmospheric band, and O(1S) greenline emissions in the Mesosphere and Lower Thermosphere (MLT) region. Our results show that the OHCD-00 produces the largest wave-induced OH(8,3) airglow intensity variation (∼34%), followed by the OHCD-90 (∼30%), then by the OHCD (∼22%). For O(1S) greenline, the MACD produces the largest wave-induced variation (∼33%), followed by the MACD-90 (∼28%), then by MACD-00 (∼26%). As for O2(0,1) atmospheric band, the MACD produces the largest wave-induced variation (∼31%), followed by the MACD-90 and MACD-00 (∼29%). Our study illustrates the importance and the need for a good atmospheric reference model that can accurately represent the atmosphere.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2017.08.020
      Issue No: Vol. 171 (2018)
  • Assessment of the NeQuick-2 and IRI-Plas 2017 models using global and
           long-term GNSS measurements
    • Authors: Daniel Okoh; Sylvester Onwuneme; Gopi Seemala; Shuanggen Jin; Babatunde Rabiu; Bruno Nava; Jean Uwamahoro
      Pages: 1 - 10
      Abstract: Publication date: Available online 22 February 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Daniel Okoh, Sylvester Onwuneme, Gopi Seemala, Shuanggen Jin, Babatunde Rabiu, Bruno Nava, Jean Uwamahoro
      The global ionospheric models NeQuick and IRI-Plas have been widely used. However, their uncertainties are not clear at global scale and long term. In this paper, a climatologic assessment of the NeQuick and IRI-Plas models is investigated at a global scale from global navigation satellite system (GNSS) observations. GNSS observations from 36 globally distributed locations were used to evaluate performances of both NeQuick-2 and IRI-Plas 2017 models from January 2006 to July 2017, covering more than the 11-year period of a solar cycle. An hourly interval of diurnal profiles computed on monthly basis was used to measure deviations of the model estimations from corresponding GNSS VTEC observations. Results show that both models are fairly accurate in trends with the GNSS measurements. The NeQuick predictions were generally better than the IRI-Plas predictions in most of the stations and the times. The mean annual prediction errors for the IRI-Plas model typically varied from about 3 TECU at the high latitude stations to about 12 TECU at the low latitude stations, while for the NeQuick the values are respectively about 2–7 TECU. Out of a total 4497 months in which GNSS data were available for all the stations put together for the entire period covered in this work, the NeQuick model was observed to perform better in about 83% of the months while the IRI-Plas performed better in about 17% of the months. The IRI-Plas generally performed better than the NeQuick at certain locations (e.g. DAV1, KERG, and ADIS). For both models, the most of the deviations were witnessed during local daytimes and during seasons that receive maximum solar radiation for various locations. In particular, the IRI-Plas model predictions were improved during periods of increased solar activity at the low latitude stations. The IRI-Plas model overestimates the GNSS VTEC values, except during high solar activity years at some high latitude stations. The NeQuick underestimates the TEC values during the high solar activity years and overestimates it during local daytime for low and moderate solar activity years, but not as much as the IRI-Plas does.

      PubDate: 2018-02-26T14:37:17Z
      DOI: 10.1016/j.jastp.2018.02.006
      Issue No: Vol. 170 (2018)
  • Rain attenuation studies from radiometric and rain DSD measurements at two
           tropical locations
    • Authors: Tuhina Halder; Arpita Adhikari; Animesh Maitra
      Pages: 11 - 20
      Abstract: Publication date: May 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 170
      Author(s): Tuhina Halder, Arpita Adhikari, Animesh Maitra
      Efficient use of satellite communication in tropical regions demands proper characterization of rain attenuation, particularly, in view of the available popular propagation models which are mostly based on temperate climatic data. Thus rain attenuations at frequencies 22.234, 23.834 and 31.4/30 GHz over two tropical locations Kolkata (22.57°N, 88.36°E, India) and Belem (1.45°S, 48.49° W, Brazil), have been estimated for the year 2010 and 2011, respectively. The estimation has been done utilizing ground-based disdrometer observations and radiometric measurements over Earth-space path. The results show that rain attenuation estimations from radiometric data are reliable only at low rain rates (<30 mm/h). However, the rain attenuation estimations from disdrometer measurements show good agreement with the ITU-R model, even at high rain rates (upto100 mm/h). Despite having significant variability in terms of drop size distribution (DSD), the attenuation values calculated from DSD data (disdrometer measurements) at Kolkata and Belem differ a little for the rain rates below 30 mm/h. However, the attenuation values, obtained from radiometric measurements at the two places, show significant deviations ranging from 0.54 dB to 3.2 dB up to a rain rate of 30 mm/h, on account of different rain heights, mean atmospheric temperatures and climatology of the two locations.

      PubDate: 2018-04-15T08:10:18Z
      DOI: 10.1016/j.jastp.2018.02.004
      Issue No: Vol. 170 (2018)
  • Preface of the special issue: “Vertical coupling in the
           atmosphere-ionosphere system: Recent progress”
    • Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171

      PubDate: 2018-04-15T08:10:18Z
  • New global electron density observations from GPS-RO in the D- and
           E-Region ionosphere
    • Authors: Dong
      Abstract: Publication date: June 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 171
      Author(s): Dong L. Wu
      A novel retrieval technique is developed for electron density (N e ) in the D- and E-region (80–120 km) using the high-quality 50-Hz GPS radio occultation (GPS-RO) phase measurements. The new algorithm assumes a slow, linear variation in the F-region background when the GPS-RO passes through the D- and E-region, and extracts the N e profiles at 80–130 km from the phase advance signal caused by N e . Unlike the conventional Abel function, the new approach produces a sharp N e weighting function in the lower ionosphere, and the N e retrievals are in good agreement with the IRI (International Reference Ionosphere) model in terms of monthly maps, zonal means and diurnal variations. The daytime GPS-RO N e profiles can be well characterized by the α-Chapman function of three parameters (N mE , h mE and H), showing that the bottom of E-region is deepening and sharpening towards the summer pole. At high latitudes the monthly GPS-RO N e maps at 80–120 km reveal clear enhancement in the auroral zones, more prominent at night, as a result of energetic electron precipitation (EEP) from the outer radiation belt. The D-/E-region auroral N e is strongly correlated with K p on a daily basis. The new N e data allow further comprehensive analyses of the sporadic E (E s ) phenomena in connection with the background N e in the E-region. The layered (2–10 km) and fluctuated (<2 km) E s components, namely N e_Layer than N e_Pert , are extracted with respect to the background N e_Region on a profile-by-profile basis. The N e_Layer component has a strong but highly-refined peak at ∼105 km, with an amplitude smaller than N e_Region approximately by an order of magnitude. The N e_Pert component, which was studied extensively in the past, is ∼2 orders of magnitude weaker than N e_Layer . Both N e_Layer and N e_Pert are subject to significant diurnal and semidiurnal variations, showing downward progression with local time in amplitude. The 11-year solar cycle dominates the N e interannual variations, showing larger N e_Region and N e_Layer but smaller N e_Pert amplitudes in the solar maximum years. Enhanced N e profiles are often observed in the polar winter, showing good correlation with solar proton events (SPEs) and geomagnetic activity. The new methodology offers great potential for retrieving low N e in the D-region, where radio propagation and communication blackouts can occur due to enhanced ionization. For space weather applications it is recommended for GPS-RO operations to raise the top of high-rate data acquisition to ∼140 km in the future.

      PubDate: 2018-04-15T08:10:18Z
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