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Journal Cover Journal of Atmospheric and Solar-Terrestrial Physics
  [SJR: 0.934]   [H-I: 70]   [156 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1364-6826
   Published by Elsevier Homepage  [3177 journals]
  • Investigation of optical and radiative properties of aerosols during an
           intense dust storm: A regional climate modeling approach
    • Authors: Sherin Hassan Bran; Subin Jose; Rohit Srivastava
      Pages: 21 - 31
      Abstract: Publication date: March 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 168
      Author(s): Sherin Hassan Bran, Subin Jose, Rohit Srivastava
      The dynamical and optical properties of aerosols during an intense dust storm event over the Arabian Sea have been studied using Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) and space borne instruments such as MODIS, MISR, CALIPSO and CERES during the period 17 to 24 March, 2012. The model captures the spatio-temporal and vertical variations of meteorological and optical parameters, however an overestimation in simulated aerosol optical parameters are observed when compared to satellite retrievals. The correlation coefficients (R) between simulated and observed AOD from MODIS and MISR are found to be 0.54 and 0.32 respectively. Model simulated AOD on dusty days (20 and 21 March 2012) increased by 2–3 times compared to non-dusty days (17 and 24 March 2012) and the single scattering albedo (SSA) and the asymmetry parameter increased from 0.96 to 0.99 and from 0.56 to 0.66, respectively. The R between simulated shortwave (SW) radiation at top of the atmosphere (TOA) and TOA SW radiation obtained from CERES is found to be 0.43, however the model simulated SW radiation at the TOA showed an underestimation with respect to CERES. The shortwave aerosol radiative forcing (SWARF) during the event over surface and TOA are ∼ -19.3 and ∼ -14.2 Wm-2 respectively, which is about 2–5 times higher when compared to the respective forcing values during non-dust days. Estimated net radiative forcing was in the range of −13 to −21 Wm-2 at TOA and −12 to −20 Wm-2 at the surface. The heating rate during event days within the lower atmosphere near 850 hPa is found to 0.32 − 0.4 K day−1 and 0.18 − 0.22 K day−1 on dusty and non-dusty days, respectively. Results of this study may be useful for a better modeling of atmospheric aerosols and its optical and radiative properties over oceanic region.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.003
      Issue No: Vol. 168 (2018)
  • Relationship between PC index and magnetospheric field-aligned currents
           measured by Swarm satellites
    • Authors: О. Troshichev; D. Sormakov; R. Behlke
      Pages: 37 - 47
      Abstract: Publication date: March 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 168
      Author(s): О. Troshichev, D. Sormakov, R. Behlke
      The relationship between the magnetospheric field-aligned currents (FAC) monitored by the Swarm satellites and the magnetic activity PC index (which is a proxy of the solar wind energy incoming into the magnetosphere) is examined. It is shown that current intensities measured in the R1 and R2 FAC layers at the poleward and equtorward boundaries of the auroral oval are well correlated, the R2 currents being evidently secondary in relation to R1 currents and correlation in the dawn and dusk oval sectors being better than in the noon and night sectors. There is evident relationship between the PC index and the intensity of field-aligned currents in the R1 dawn and dusk layers: increase of FAC intensity in the course of substorm development is accompanied by increasing the PC index values. Correlation between PC and FAC intensities in the R2 dawn and dusk layers is also observed, but it is much weaker. No correlation is observed between PC and field-aligned currents in the midnight as well as in the noon sectors ahead of the substorm expansion phase. The results are indicative of the R1 field-aligned currents as a driver of the polar cap magnetic activity (PC index) and currents in the R2 layer.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2017.12.020
      Issue No: Vol. 168 (2018)
  • Parameterization of water vapor using high-resolution GPS data and
           empirical models
    • Authors: Shantikumar S. Ningombam; Sridevi Jade; T.S.Shrungeshwara
      Pages: 58 - 69
      Abstract: Publication date: March 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 168
      Author(s): Shantikumar S. Ningombam, Sridevi Jade, T.S.Shrungeshwara
      The present work evaluates eleven existing empirical models to estimate Precipitable Water Vapor ( P W V ) over a high-altitude (4500 m amsl), cold-desert environment. These models are tested extensively and used globally to estimate P W V for low altitude sites (below 1000 m amsl). The moist parameters used in the model are: water vapor scale height ( H c ), dew point temperature ( T d ) and water vapor pressure ( E s 0 ). These moist parameters are derived from surface air temperature and relative humidity measured at high temporal resolution from automated weather station. The performance of these models are examined statistically with observed high-resolution GPS ( G P S P W V ) data over the region (2005–2012). The correlation coefficient (R) between the observed G P S P W V and Model P W V is 0.98 at daily data and varies diurnally from 0.93 to 0.97. Parameterization of moisture parameters were studied in-depth (i.e., 2 h to monthly time scales) using G P S P W V , T d , and E s 0 . The slope of the linear relationships between G P S P W V and T d varies from 0.073°C−1 to 0.106°C−1 (R: 0.83 to 0.97) while G P S P W V and E s 0 varied from 1.688 to 2.209 (R: 0.95 to 0.99) at daily, monthly and diurnal time scales. In addition, the moist parameters for the cold desert, high-altitude environment are examined in-depth at various time scales during 2005–2012.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.009
      Issue No: Vol. 168 (2018)
  • A preliminary comparison of Na lidar and meteor radar zonal winds during
           geomagnetic quiet and disturbed conditions
    • Authors: G. Kishore Kumar; H. Nesse Tyssøy; Bifford P. Williams
      Pages: 70 - 79
      Abstract: Publication date: March 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 168
      Author(s): G. Kishore Kumar, H. Nesse Tyssøy, Bifford P. Williams
      We investigate the possibility that sufficiently large electric fields and/or ionization during geomagnetic disturbed conditions may invalidate the assumptions applied in the retrieval of neutral horizontal winds from meteor and/or lidar measurements. As per our knowledge, the possible errors in the wind estimation have never been reported. In the present case study, we have been using co-located meteor radar and sodium resonance lidar zonal wind measurements over Andenes (69.27°N, 16.04°E) during intense substorms in the declining phase of the January 2005 solar proton event (21–22 January 2005). In total, 14 h of measurements are available for the comparison, which covers both quiet and disturbed conditions. For comparison, the lidar zonal wind measurements are averaged over the same time and altitude as the meteor radar wind measurements. High cross correlations (∼0.8) are found in all height regions. The discrepancies can be explained in light of differences in the observational volumes of the two instruments. Further, we extended the comparison to address the electric field and/or ionization impact on the neutral wind estimation. For the periods of low ionization, the neutral winds estimated with both instruments are quite consistent with each other. During periods of elevated ionization, comparatively large differences are noticed at the highermost altitude, which might be due to the electric field and/or ionization impact on the wind estimation. At present, one event is not sufficient to make any firm conclusion. Further study with more co-located measurements are needed to test the statistical significance of the result.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.010
      Issue No: Vol. 168 (2018)
  • Nighttime mesospheric ozone enhancements during the 2002 southern
           hemispheric major stratospheric warming
    • Authors: Christine Smith-Johnsen; Yvan Orsolini; Frode Stordal; Varavut Limpasuvan; Kristell Pérot
      Pages: 100 - 108
      Abstract: Publication date: March 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 168
      Author(s): Christine Smith-Johnsen, Yvan Orsolini, Frode Stordal, Varavut Limpasuvan, Kristell Pérot
      Sudden Stratospheric Warmings (SSW) affect the chemistry and dynamics of the middle atmosphere. Major warmings occur roughly every second winter in the Northern Hemisphere (NH), but has only been observed once in the Southern Hemisphere (SH), during the Antarctic winter of 2002. Observations by the Global Ozone Monitoring by Occultation of Stars (GOMOS, an instrument on board Envisat) during this rare event, show a 40% increase of ozone in the nighttime secondary ozone layer at subpolar latitudes compared to non-SSW years. This study investigates the cause of the mesospheric nighttime ozone increase, using the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model with specified dynamics (SD-WACCM). The 2002 SH winter was characterized by several reductions of the strength of the polar night jet in the upper stratosphere before the jet reversed completely, marking the onset of the major SSW. At the time of these wind reductions, corresponding episodic increases can be seen in the modelled nighttime secondary ozone layer. This ozone increase is attributed largely to enhanced upwelling and the associated cooling of the altitude region in conjunction with the wind reversal. This is in correspondence to similar studies of SSW induced ozone enhancements in NH. But unlike its NH counterpart, the SH secondary ozone layer appeared to be impacted less by episodic variations in atomic hydrogen. Seasonally decreasing atomic hydrogen plays however a larger role in SH compared to NH.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2017.12.018
      Issue No: Vol. 168 (2018)
  • Storm phase–partitioned rates and budgets of global Alfvénic energy
           deposition, electron precipitation, and ion outflow
    • Authors: Spencer M. Hatch; James LaBelle; Christopher C. Chaston
      Pages: 1 - 12
      Abstract: Publication date: January 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 167
      Author(s): Spencer M. Hatch, James LaBelle, Christopher C. Chaston
      We review the role of Alfvén waves in magnetosphere-ionosphere coupling during geomagnetically active periods, and use three years of high-latitude FAST satellite observations of inertial Alfvén waves (IAWs) together with 55 years of tabulated measurements of the Dst index to answer the following questions: 1) How do global rates of IAW-related energy deposition, electron precipitation, and ion outflow during storm main phase and storm recovery phase compare with global rates during geomagnetically quiet periods' 2) What fraction of net IAW-related energy deposition, electron precipitation, and ion outflow is associated with storm main phase and storm recovery phase; that is, how are these budgets partitioned by storm phase' We find that during the period between October 1996 and November 1999, rates of IAW-related energy deposition, electron precipitation, and ion outflow during geomagnetically quiet periods are increased by factors of 4–5 during storm phases. We also find that ∼ 62–68% of the net Alfvénic energy deposition, electron precipitation, and ion outflow in the auroral ionosphere occurred during storm main and recovery phases, despite storm phases comprising only 31% of this period. In particular storm main phase, which comprised less than 14% of the three-year period, was associated with roughly a third of the total Alfvénic energy input and ion outflow in the auroral ionosphere. Measures of geomagnetic activity during the IAW study period fall near corresponding 55-year median values, from which we conclude that each storm phase is associated with a fraction of total Alfvénic energy, precipitation, and outflow budgets in the auroral ionosphere that is, in the long term, probably as great or greater than the fraction associated with geomagnetic quiescence for all times except possibly those when geomagnetic activity is protractedly weak, such as solar minimum. These results suggest that the budgets of IAW-related energy deposition, electron precipitation, and ion outflow are roughly equally partitioned by geomagnetic storm phase.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2017.08.009
      Issue No: Vol. 167 (2018)
  • Detecting atmospheric normal modes with periods less than 6 h by
           barometric observations
    • Abstract: Publication date: April 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 169
      Author(s): S.I. Ermolenko, G.M. Shved, Ch. Jacobi
      The theory of atmospheric normal modes (ANMs) predicts the existence of relatively short-period gravity-inertia ANMs. Simultaneous observations of surface air-pressure variations by barometers at distant stations of the Global Geodynamics Project network during an interval of 6 months were used to detect individual gravity-inertia ANMs with periods of ∼2–5 h. Evidence was found for five ANMs with a lifetime of ∼10 days. The data of the stations, which are close in both latitude and longitude, were utilized for deriving the phases of the detected ANMs. The phases revealed wave propagation to the west and increase of zonal wavenumbers with frequency. As all the detected gravity-inertia ANMs are westward propagating, they are suggested to be generated due to the breakdown of migrating solar tides and/or large-scale Rossby waves. The existence of an ANM background will complicate the detection of the translational motions of the Earth's inner core.

      PubDate: 2018-02-26T14:37:17Z
  • Causes of the mid-latitudinal daytime NmF2 semi-annual anomaly at solar
    • Abstract: Publication date: April 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 169
      Author(s): A.V. Pavlov
      Ionospheric ionosonde and radar observations and theoretical calculations of the F2-layer peak altitude, hmF2, and number density, NmF2, over Millstone Hill during winter, spring, summer, and autumn geomagnetically quiet time periods at low solar activity are used to study the causes of the observed daytime NmF2 semi-annual anomaly. It follows from the model simulations that this anomalous phenomenon arises in the ionosphere mainly as a result of seasonal variations of the following atmospheric parameters: (1) the plasma drift along geomagnetic field lines due to corresponding changes in neutral wind components, (2) temperature and number densities of the neutral atmosphere, and (3) an optical thickness of the atmosphere caused by the dependence of the solar zenith angle on the day of the year for the same solar local time. Seasonal variations of the production rate unexcited O+ ions due to chemical reactions involving electronically excited O+ ions contribute to the formation of the NmF2 semi-annual anomaly during the predominant part of the existence time of this anomalous phenomenon. However, these seasonal variations are not significant, and this mechanism should be considered only as an additional source of the NmF2 semi-annual anomaly during its time of existence. The reactions of unexcited O+ ions with vibrationally excited N2 and O2 cause only weak changes of NmF2 and these changes are close in magnitude at a given solar local time during the winter, spring, summer, and autumn daytime conditions under consideration. Ignoring these reactions cannot produce a significant impact on the formation of the NmF2 semi-annual anomaly.

      PubDate: 2018-02-26T14:37:17Z
  • Response of noctilucent cloud brightness to daily solar variations
    • Abstract: Publication date: April 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 169
      Author(s): P. Dalin, N. Pertsev, V. Perminov, A. Dubietis, A. Zadorozhny, M. Zalcik, I. McEachran, T. McEwan, K. Černis, J. Grønne, T. Taustrup, O. Hansen, H. Andersen, D. Melnikov, A. Manevich, V. Romejko, D. Lifatova
      For the first time, long-term data sets of ground-based observations of noctilucent clouds (NLC) around the globe have been analyzed in order to investigate a response of NLC to solar UV irradiance variability on a day-to-day scale. NLC brightness has been considered versus variations of solar Lyman-alpha flux. We have found that day-to-day solar variability, whose effect is generally masked in the natural NLC variability, has a statistically significant effect when considering large statistics for more than ten years. Average increase in day-to-day solar Lyman-α flux results in average decrease in day-to-day NLC brightness that can be explained by robust physical mechanisms taking place in the summer mesosphere. Average time lags between variations of Lyman-α flux and NLC brightness are short (0–3 days), suggesting a dominant role of direct solar heating and of the dynamical mechanism compared to photodissociation of water vapor by solar Lyman-α flux. All found regularities are consistent between various ground-based NLC data sets collected at different locations around the globe and for various time intervals. Signatures of a 27-day periodicity seem to be present in the NLC brightness for individual summertime intervals; however, this oscillation cannot be unambiguously retrieved due to inevitable periods of tropospheric cloudiness.

      PubDate: 2018-02-26T14:37:17Z
  • Response of the dynamic and thermodynamic structure of the stratosphere to
           the solar cycle in the boreal winter
    • Abstract: Publication date: April 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 169
      Author(s): Chunhua Shi, Yannan Gao, Juan Cai, Dong Guo, Yan Lu
      The response of the dynamic and thermodynamic structure of the stratosphere to the solar cycle in the boreal winter is investigated based on measurements of the solar cycle by the Spectral Irradiance Monitor onboard the SORCE satellite, monthly ERA-Interim Reanalysis data from the European Center for Medium-Range Weather Forecasts, the radiative transfer scheme of the Beijing Climate Center (BCC-RAD) and a multiple linear regression model. The results show that during periods of strong solar activity, the solar shortwave heating anomaly from the climatology in the tropical upper stratosphere triggers a local warm anomaly and strong westerly winds in mid-latitudes, which strengthens the upward propagation of planetary wave 1 but prevents that of wave 2. The enhanced westerly jet makes a slight adjustment to the propagation path of wave 1, but prevents wave 2 from propagating upward, decreases the dissipation of wave 2 in the extratropical upper stratosphere and hence weakens the Brewer–Dobson circulation. The adiabatic heating term in relation to the Brewer-Dobson circulation shows anomalous warming in the tropical lower stratosphere and anomalous cooling in the mid-latitude upper stratosphere.

      PubDate: 2018-02-26T14:37:17Z
  • Effects of sporadic E-layer characteristics on spread-F generation in the
           nighttime midlatitude ionosphere: A climatological study
    • Abstract: Publication date: April 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 169
      Author(s): C.C. Lee, W.S. Chen
      The aim of this study is to examine the effects of Es-layer characteristics on spread-F generation in the nighttime midlatitude ionosphere. The Es-layer parameters and spread-F appearance of the 23rd solar cycle (1996–2008) are recorded by the Kokubunji ionosonde. The Es-layer parameters are foEs (critical frequency of Es-layer), fbEs (blanketing frequency of Es-layer), and Δf (≡foEs-fbEs). In order to completely explore the effects, the pre-midnight and post-midnight data are classified by seasons, solar activities, and geomagnetic conditions. Results show that the spread-F occurs more frequently in post-midnight and in summer. And, the occurrence probabilities of spread-F are greater, when the solar activity is lower. For the occurrence probabilities of spread-F versus foEs and Δf under geomagnetic quiet-conditions, the trend is increasing, when the associated probabilities are significant. These indicate that the spread-F occurrence increases with increasing foEs and/or Δf. Further, the increasing trends demonstrate that polarization electric fields generated in Es-layer would be helpful to generate spread-F, through the electrodynamical coupling of Es-layer and F-region. Moreover, this electrodynamical coupling is efficient not only under quiet-conditions but under disturbed-conditions, since the significant increasing trend can also be found under disturbed-conditions. Regarding the occurrence probabilities of spread-F versus fbEs, the evident trends are not in the majority. This implies that fbEs might not be a major factor for the spread-F formation.

      PubDate: 2018-02-26T14:37:17Z
  • Assessment of the NeQuick-2 and IRI-Plas 2017 models using global and
           long-term GNSS measurements
    • 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
  • The generation of post noon F3 layers over the dip equatorial location of
           Thiruvananthapuram- A new perspective
    • Abstract: Publication date: Available online 21 February 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): N. Mridula, Tarun Kumar Pant
      In the present paper, occurrence of post noon F3 layers over Thiruvananthapuram (8.5°N; 77°E; dip latitude ∼ 1.5 °N), a dip equatorial station in India have been investigated. F3 layers that occur beyond 13 IST and as observed using ground based ionosonde, for the years 2004–2008 have been studied. Our analysis shows that post noon F3 layers occur mostly on CEJ days around 16 IST to 18 IST. It is found that the time of the ionospheric E−region electric field reversal as inferred from collocated ground based magnetometer observations plays a crucial role in the generation of post noon F3 layers. In fact an early reversal of electric field emerged to be the necessary condition for the formation of post noon F3 layers. A time delay of three to 4 h is observed between the electric field reversal and the formation of F3 layer. It is proposed that this early reversal causes enhanced ionization over dip equatorial region, providing an additional ion drag to the flow of thermospheric zonal wind. This leads to accumulation of more ionization and neutrals culminating in the generation of post noon F3 layers as in the case of pre noon F3 layers. These results reveal that the generation of post noon F3 layers over the dip equatorial region is a natural consequence of the variability associated with the spatio-temporal evolution of EIA and prevailing thermospheric and ionospheric dynamics, and adds a new perspective to the present understanding.

      PubDate: 2018-02-26T14:37:17Z
  • Aerosols and seismo-ionosphere coupling: A review
    • 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
  • Magnetospheric Multiscale Observations of Turbulent Magnetic and Electron
           Velocity Fluctuations in Earth's Magnetosheath Downstream of a
           quasi-parallel bow shock
    • Abstract: Publication date: Available online 13 February 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): C.J. Pollock, J.L. Burch, A. Chasapis, B.L. Giles, D.A. Mackler, W.H. Matthaeus, C.T. Russell
      We present statistical single-spacecraft observations of magnetic and electron velocity fluctuations in Earth's magnetosheath, likely in the vicinity of the magnetopause, downstream of a bow shock immersed in quasi-parallel interplanetary magnetic field conditions, a situation conducive to plasma turbulence in the downstream flow. These fluctuations exhibit scale-dependent behavior, wherein histograms of their Partial Variance of Increments (PVIB or PVIVe) demonstrate highly non-Gaussian forms at small scales and are reasonably well-described by kappa distributions, albeit with fitted values of the kappa parameter only slightly larger than 1.5, exemplifying their power law nature at large values of PVI. At larger scales, the PVI histograms lose their non-Gaussian nature and are well described by both Gaussian and kappa distributions with large values of the kappa parameter. The PVI histograms furthermore exhibit kurtosis that increases with decreasing scale, a characteristic that is much more prominent in the magnetic fluctuations than in the electron velocity fluctuations. This feature that is not yet explained. In both cases, the results are characteristic of turbulent intermittency.

      PubDate: 2018-02-26T14:37:17Z
  • Effect of geomagnetic storms on the daytime low-latitude thermospheric
           wave dynamics
    • Abstract: Publication date: Available online 11 February 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Deepak K. Karan, Duggirala Pallamraju
      The equatorial- and low-latitude thermospheric dynamics is affected by both equatorial electrodynamics and neutral wave dynamics, the relative variation of which is dependent on the prevalent background conditions, which in turn has a seasonal dependence. Depending on the ambient thermospheric conditions, varying effects of the geomagnetic disturbances on the equatorial- and low-latitude thermosphere are observed. To investigate the effect of these disturbances on the equatorial- and low-latitude neutral wave dynamics, daytime airglow emission intensities at OI 557.7 nm, OI 630.0 nm, and OI 777.4 nm are used. These emissions from over a large field-of-view (FOV∼1000) have been obtained using a high resolution slit spectrograph, MISE (Multiwavelength Imaging Spectrograph using Echelle grating), from a low-latitude location, Hyderabad (17.50N, 78.40E; 8.90N MLAT), in India. Variations of the dayglow emission intensities are investigated during three geomagnetic disturbance events that occurred in different seasons. It is seen that the neutral dayglow emission intensities at all the three wavelengths showed different type of variations with the disturbance storm time (Dst) index in different seasons. Even though the dayglow emission intensities over low-latitude regions are sensitive to the variation in the equatorial electric fields, during periods of geomagnetic disturbances, especially in solstices, these are dependent on thermospheric O/N2 values. This shows the dominance of neutral dynamics over electrodynamics in the low-latitude upper atmosphere during geomagnetic disturbances. Further, spectral analyses have been carried out to obtain the zonal scale sizes in the gravity wave regime and their diurnal distributions are compared for geomagnetic quiet and disturbed days. Broadly, the zonal scales seem to be breaking into various scale sizes on days of geomagnetic disturbances when compared to those on quiet days. This contrast in the diurnal distribution of the zonal scale sizes brings to light, for the first time, the varying nature of the neutral wave coupling in the daytime thermosphere during periods of geomagnetic disturbances.

      PubDate: 2018-02-26T14:37:17Z
  • Integration of RAM-SCB into the Space Weather Modeling Framework
    • Abstract: Publication date: Available online 7 February 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Daniel T. Welling, Gabor Toth, Vania K. Jordanova, Yiqun Yu
      Numerical simulations of the ring current are a challenging endeavor. They require a large set of inputs, including electric and magnetic fields and plasma sheet fluxes. Because the ring current broadly affects the magnetosphere-ionosphere system, the input set is dependent on the ring current region itself. This makes obtaining a set of inputs that are self-consistent with the ring current difficult. To overcome this challenge, researchers have begun coupling ring current models to global models of the magnetosphere-ionosphere system. This paper describes the coupling between the Ring current Atmosphere interaction Model with Self-Consistent Magnetic field (RAM-SCB) to the models within the Space Weather Modeling Framework. Full details on both previously introduced and new coupling mechanisms are defined. The impact of self-consistently including the ring current on the magnetosphere-ionosphere system is illustrated via a set of example simulations.

      PubDate: 2018-02-26T14:37:17Z
  • Plausible modulation of solar wind energy flux input on global tropical
           cyclone activity
    • Abstract: Publication date: Available online 6 February 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Hui Li, Chi Wang, Shengping He, Huijun Wang, Cui Tu, Jiyao Xu, Fei Li, Xiaocheng Guo
      Studies on Sun-climate connection have been carried out for several decades, and almost all of them focused on the effects of solar total irradiation energy. As the second major terrestrial energy source from outer space, the solar wind energy flux exhibits more significant long-term variations. However, its link to the global climate change is rarely concerned and remains a mystery. As a fundamental and important aspect of the Earth's weather and climate system, tropical cyclone activity has been causing more and more attentions. Here we investigate the possible modulation of the total energy flux input from the solar wind into the Earth's magnetosphere on the global tropical cyclone activity during 1963–2012. From a global perspective, the accumulated cyclone energy increases gradually since 1963 and starts to decrease after 1994. Compare to the previously frequently used parameters, e.g., the sunspot number, the total solar irradiation, the solar F10.7 irradiation, the tropical sea surface temperature, and the south oscillation index, the total solar wind energy flux input exhibits a better correlation with the global tropical cyclone activity. Furthermore, the tropical cyclones seem to be stronger with more intense geomagnetic activities. A plausible modulation mechanism is thus proposed to link the terrestrial weather phenomenon to the seemingly-unrelated solar wind energy input.

      PubDate: 2018-02-26T14:37:17Z
  • Spectral characteristic of geomagnetically induced current during
           geomagnetic storms by wavelet techniques
    • Authors: Binod Adhikari; Nirakar Sapkota; Subodh Dahal; Binod Bhattarai; Krishna Khanal; Narayan P. Chapagain
      Abstract: Publication date: Available online 2 February 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Binod Adhikari, Nirakar Sapkota, Subodh Dahal, Binod Bhattarai, Krishna Khanal, Narayan P. Chapagain
      An EMF (electromagnetic field) is induced over an incremental area when magnetized plasma from sun interacts with the Earth's magnetic field. This phenomenon delivers a Geomagnetically Induced Current (GIC) or induces geo-electric field at the Earth's surface and in the ground. GIC and horizontal component of geomagnetic field have been studied with respect to various geomagnetic events. Particularly, we have studied four events. The first one is geomagnetically quiet period (5 October 2003), the second one is weak storm (21 October 2003), the third one is moderate storm (14 October 2003) and the last one is an intense storm (30 October 2003). By comparing the development of GIC during geomagnetic storms, we found that intense geomagnetic storms show higher development on GIC magnitude. The GIC during storm events is several times greater than that during the quiet day. AE index shows more activity in the event of 30th October than other events and GIC is also more in this event. This can be accounted to the greater geomagnetic disturbance in this case. The power ranges of higher intensity are seen at various time scales on different events. We have analysed GIC signal associated with four geomagnetic storms and found distinct periodicities at the time when H component highly perturbed. The characteristic of GIC signal demonstrates high variability with time without presence of continuous periodicities. Discrete wavelet transform (DWT) analysis reveals that whenever the geomagnetic field is perturbed, there will be high possibility of detecting GIC. The singularities present in GIC signal are due to the peak value of electrical currents system in the ionosphere and magnetosphere, and corresponding high fluctuations in H component. In this work, we explore the remarkable ability of wavelets to highlight the singularities associated with discontinuities present in the GIC.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.020
  • Modeling the global ionospheric variations based on complex network
    • Authors: Shikun Lu; Hao Zhang; Xihai Li; Yihong Li; Chao Niu; Xiaoyun Yang; Daizhi Liu
      Abstract: Publication date: Available online 1 February 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Shikun Lu, Hao Zhang, Xihai Li, Yihong Li, Chao Niu, Xiaoyun Yang, Daizhi Liu
      The modern science of networks has brought significant advances to our understanding of complex systems. We employ the probabilistic graphical model to build complex networks to model the global ionospheric variations. The global ionospheric maps (GIMs) of vertical total electron content (VTEC) for the 12 months in 2012 have been selected analyze the ionospheric variations from the perspective of complex network. The information flow in the networks represents the causal interactions between the ionospheric variations at different locations. The distributions of the edges' geospatial distances in the ionospheric networks show that the information flow in the ionosphere is mainly transmitted locally, almost obeying the geospatial proximity principle. The asymmetric distribution of the edges' distances probably elucidates the more efficient transmission of ionospheric variations in the westward and southward directions. The community topologies within the ionospheric networks indicate the effect of the geomagnetic field and geographical distance on the information flow in the ionosphere. The geomagnetic field has shown an enhanced effect on the meridional interaction in the ionosphere, causing the vertical community topologies within the ionospheric networks at middle and low latitudes. For the ionospheric cells located at high latitudes in GIM, the geographical distances result in the horizontal community topologies. The fractal analysis reveals the existence of self-similar structure in the ionospheric networks on the global scale. The fractality in the ionospheric information flow may indicate the reasonability of the VTEC's prediction at a certain location by spatial prediction based on the data obtained in known regions.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.017
  • Storm-time variations of atomic nitrogen 149.3 nm emission
    • Authors: Y. Zhang; L.J. Paxton; D. Morrison; B. Schaefer
      Abstract: Publication date: Available online 1 February 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Y. Zhang, L.J. Paxton, D. Morrison, B. Schaefer
      Net radiances of atomic nitrogen emission line (N-149.3 nm) from the thermosphere are extracted from the FUV spectra observed by TIMED/GUVI on dayside at sunlit latitudes. During geomagnetic storms, the N-149.3 nm intensity is clearly enhanced in the locations where O/N2 depletion and nitric oxide (NO) enhancement are observed. The N-149.3 nm intensity is linearly and tightly correlated with N2 LBHS (140–150 nm) radiance with a fixed LBHS/149.3 nm ratio of ∼4.5, suggesting that dissociation of N2 is the dominant source of the N-149.3 nm emission. In the regions without storm disturbances, the N-149.3 nm intensities are closely correlated with solar EUV flux.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.023
  • Statistic study of the geoeffectiveness of compression regions CIRs and
    • Authors: Yu I. Yermolaev; I.G. Lodkina; N.S. Nikolaeva; M.Yu Yermolaev; M.O. Riazantseva; L.S. Rakhmanova
      Abstract: Publication date: Available online 31 January 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Yu I. Yermolaev, I.G. Lodkina, N.S. Nikolaeva, M.Yu Yermolaev, M.O. Riazantseva, L.S. Rakhmanova
      We statistically study the geoeffectiveness of two types of compression regions: corotating interaction regions (CIRs) before the solar wind high-speed streams (HSSs) from the coronal holes and Sheaths before the fast interplanetary CMEs (ICMEs) including flux-rope magnetic clouds (MCs) and non-MC Ejecta using the OMNI dataset ( (King and Papitashvili, 2004)) and our Catalog of large-scale solar wind phenomena for 1976–2000 ( et al., 2009)). Our analysis shows that the magnitude of the interplanetary magnetic field B in CIRs and Sheaths increases with increasing speed of both types of pistons: HSS and ICME; the increase of the piston speed results in the increase of geoeffectiveness of both compression regions. The value B in Sheaths before Ejecta is higher than B in Ejecta. The value B in Sheaths before MCs in the beginning of phenomena interval is lower than in MCs but in the end of interval it is close to B in MCs. The contribution of Sheath in storm generation can be significant for so-called "CME-induced" storms and Sheath-induced storms should be identified and analyzed separately.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.027
  • Application of solar quiet (Sq) current in determining mantle
           conductivity-depth structure in Malaysia
    • Authors: Zamri Zainal Abidin; M.H. Jusoh; M. Abbas; A. Yoshikawa
      Abstract: Publication date: Available online 31 January 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Zamri Zainal Abidin, M.H. Jusoh, M. Abbas, A. Yoshikawa
      The mantle electrical conductivity-depth structure of Malaysia was determined for the first time using solar quiet day ionospheric current (Sq) variations. Spherical harmonic analysis (SHA) was employed to separate the external and internal field contribution to the Sq variations. A transfer function was applied in estimating the conductivity-depth profile for the paired of external and internal coefficients of the SHA. We observed a downward increase in electrical conductivity with initial magnitude of 0.0065 S/m at a depth of ∼ 56 km which gradually rose to 0.0106 and 0.0140 S/m at 118 and 180 km. Subsequently, the conductivity profile rose to about 0.0228 S/m at 380 km (near the base of the upper mantle) and reached 0.0260 S/m at 435 km, after which a sharp steep increase was observed at 450 km with conductivity profile of 0.0278 S/m. Consequently, the conductivity profile increases significantly to about 0.1367 S/m at a depth of 973 km and reached its peak value 0.1975 S/m at the depth of 1097 km in the lower mantle with no indication of leveling off. An evidence of discontinuity was observed near 390–460 km and 675–746 km. A slight increase in conductivity values at depth between 150 and 300 km corresponds to the region of unusual global low velocity zone with high electrical conductivity. The conductivity profile showed a less steep increase above 450 km below which a steep increase was observed. The present profile showed the deepest penetration depth which may be attributed to the influence of equatorial electrojet current (EEJ) that is actively supported by the conductive properties of the Earth's interior within the study region.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.019
  • Response of equatorial and low latitude mesosphere lower thermospheric
           dynamics to the northern hemispheric sudden stratospheric warming events
    • Authors: N. Koushik; Karanam Kishore Kumar; Geetha Ramkumar; K.V. Subrahmanyam
      Abstract: Publication date: Available online 20 January 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): N. Koushik, Karanam Kishore Kumar, Geetha Ramkumar, K.V. Subrahmanyam
      The changes in zonal mean circulation and meridional temperature gradient brought about by Sudden Stratospheric Warming (SSW) events in polar middle atmosphere are found to significantly affect the low latitude counterparts. Several studies have revealed the signatures of SSW events in the low latitude Mesosphere- Lower Thermosphere (MLT) region. Using meteor wind radar observations, the present study investigates the response of semidiurnal oscillations and quasi 2-day waves in the MLT region, simultaneously over low latitude and equatorial stations Thumba (8.5oN, 76.5oE) and Kototabang (0.2oS, 100oE). Unlike many case studies, the present analysis examines the response of low and equatorial latitude MLT region to typical polar stratospheric conditions viz., Quiet winter, Major SSW winter and Minor SSW winter. The present results show that (i) the amplitudes of semidiurnal oscillations and quasi 2-day waves in the equatorial and low latitude MLT region enhance in association with major SSW events, (ii) the semidiurnal oscillations show significant enhancement selectively in the zonal and meridional components over the Northern Hemispheric low latitude and the equatorial stations, respectively (iii) The minor SSW event of January 2012 resulted in anomalously large amplitudes of quasi 2- day waves without any notable increase in the amplitude of semidiurnal oscillations. The significance of the present study lies in comprehensively bringing out the signatures of SSW events in the semidiurnal oscillations and quasi 2-day waves in low latitude and equatorial MLT region, simultaneously for the first time over these latitudes.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.021
  • Amplitude variations of ELF radio waves in the Earth–ionosphere cavity
           with the day–night non-uniformity
    • Authors: Yu P. Galuk; A.P. Nickolaenko; M. Hayakawa
      Abstract: Publication date: Available online 8 January 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Yu P. Galuk, A.P. Nickolaenko, M. Hayakawa
      The real structure of lower ionosphere should be taken into account when modeling the sub–ionospheric radio propagation in the extremely low frequency (ELF) band and studying the global electromagnetic (Schumann) resonance of the Earth–ionosphere cavity. In the present work we use the 2D (two dimensional) telegraph equations (2DTE) for evaluating the effect of the ionosphere day-night non-uniformity on the electromagnetic field amplitude at the Schumann resonance and higher frequencies. Properties of the cavity upper boundary were taken into account by the full wave solution technique for realistic vertical profiles of atmosphere conductivity in the ambient day and ambient night conditions. We solved the electromagnetic problem in a cavity with the day–night non-uniformity by using the 2DTE technique. Initially, the testing of the 2DTE solution was performed in the model of the sharp day–night interface. The further computations were carried out in the model of the smooth day–night transition. The major attention was directed to the effects at propagation paths "perpendicular" or "parallel" to the solar terminator line. Data were computed for a series of frequencies, the comparison of the results was made and interpretation was given to the observed effects.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.001
  • Extension of ITU-R method for 1-hour to 1-minute conversion of rain rate
           statistics for satellite propagation in Malaysia
    • Authors: Yun Yann Ng; Mandeep Singh Jit Singh; Vinesh Thiruchelvam
      Abstract: Publication date: Available online 8 January 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Yun Yann Ng, Mandeep Singh Jit Singh, Vinesh Thiruchelvam
      1-min rain rate is the key element to precisely predicting rain attenuation at a given location. However, there is a limitation in 1-min rain rate availability in Malaysia for long-term local measurement, because rain rate statistics are commonly derived on the rain gauge recordings base with actual integration times of 10 min or longer. Therefore, conversion of available rain rate distributions with longer integration times to 1-min rain rate distributions is necessary. This study proposes a novel set of coefficients to current ITU-R for Malaysia in order to improve the accuracy of the 1-h to 1-min rain rate conversion process. According to the results, the test indicates that the proposed set of coefficients outperformed previous work in terms of accuracy. This study is crucial to provide more accurate regression coefficients to system designers when designing link margins.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.004
  • Understanding the global dynamics of the equatorial ionosphere in Africa
           for space weather capabilities: A science case for AfrequaMARN
    • Authors: Hammed A. Lawal; Mark Lester; Stanley W.H. Cowley; S.E. Milan; T.K. Yeoman; Gabby Provan; Suzie Imber; A.Babatunde Rabiu
      Abstract: Publication date: Available online 6 January 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Hammed A. Lawal, Mark Lester, Stanley W.H. Cowley, S.E. Milan, T.K. Yeoman, Gabby Provan, Suzie Imber, A.Babatunde Rabiu
      The equatorial region of the Earth's ionosphere is one of the most complex ionospheric regions due to its interactions, instabilities, and several unresolved questions regarding its dynamics, electrodynamics, and physical processes. The equatorial ionosphere overall spans three continents with the longest region being that over the African continent. Satellite observations have demonstrated that very large differences exist in the formation of ionospheric irregularities over the African sector compared with other longitudinal sectors. This may be a consequence of the symmetric shape of the magnetic equator over the continent and the lack of variability in latitude. In this paper, we propose a science campaign to equip the African sector of the magnetic equator with ground-based instruments, specifically magnetometers and radars. The network of radars proposed is similar in style and technique to the high-latitude SuperDARN radar network, while the magnetometers will form an array along the equatorial belt. These two proposed space physics instruments will be used to study this region of the equatorial ionosphere over a long interval of time, at least one solar cycle. The deployment of an array of magnetometers (AfrequaMA) and a radar network (AfrequaRN) in the African sector of the magnetic equator is jointly called the Africa Equatorial Magnetometer Array and Radar Network (AfrequaMARN), which will provide simultaneous observations of both electric and magnetic variations over the African sector. We also examine the possible science questions such a magnetometer array and radar network would be able to address, both individually and in conjunction with other space-based and ground-based instrumentation. The proposed projects will clearly improve our understanding of the dynamics of the equatorial ionosphere and our understanding of its role in balancing the large-scale ionospheric current system, and will contribute to our ability to adequately model ionospheric and plasmaspheric densities. It will also enhance our understanding of global ionospheric processes, which will improve the space weather capabilities of the African and international space science communities.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.008
  • Data-adaptive harmonic analysis and modeling of solar wind-magnetosphere
    • Authors: Dmitri Kondrashov; Mickaël D. Chekroun
      Abstract: Publication date: Available online 4 January 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Dmitri Kondrashov, Mickaël D. Chekroun
      The solar wind-magnetosphere coupling is studied by new data-adaptive harmonic (DAH) decomposition approach for the spectral analysis and inverse modeling of multivariate time observations of complex nonlinear dynamical systems. DAH identifies frequency-based modes of interactions in the combined dataset of Auroral Electrojet (AE) index and solar wind forcing. The time evolution of these modes can be very efficiently simulated by using systems of stochastic differential equations (SDEs) that are stacked per frequency and formed by coupled Stuart-Landau oscillators. These systems of SDEs capture the modes' frequencies as well as their amplitude modulations, and yield, in turn, an accurate modeling of the AE index' statistical properties.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2017.12.021
  • A case study of convectively generated gravity waves coupling of the lower
           atmosphere and mesosphere-lower thermosphere (MLT) over the tropical
           region: An observational evidence
    • Authors: S. Eswaraiah; G. Venkata Chalapathi; K. Niranjan Kumar; M. Venkat Ratnam; Yong Ha Kim; P. Vishnu Prasanth; Jaewook Lee; S.V.B. Rao
      Abstract: Publication date: Available online 4 January 2018
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): S. Eswaraiah, G. Venkata Chalapathi, K. Niranjan Kumar, M. Venkat Ratnam, Yong Ha Kim, P. Vishnu Prasanth, Jaewook Lee, S.V.B. Rao
      We have utilized the Gadanki MST Radar and Rayleigh LIDAR to understand the vertical coupling between the lower atmosphere and mesosphere through the short-period gravity waves (GWs). The short-period GWs (20 min–2 h) are noticed both in the troposphere and in the mesosphere during the deep convection. During the convection, the large vertical velocities (>5 m/s) and significant variations in the momentum flux (∼3 m2/s2) are noticed in the troposphere and higher fluxes (∼45 m2/s2) are evidenced in the mesosphere. The observations suggest the vertical coupling between the lower and middle atmosphere during convection.

      PubDate: 2018-02-05T13:28:08Z
      DOI: 10.1016/j.jastp.2018.01.005
  • Effect of geomagnetic storm conditions on the equatorial ionization
           anomaly and equatorial temperature anomaly
    • Authors: Gaurav Bharti; T. Bag; M.V. Sunil Krishna
      Abstract: Publication date: Available online 24 December 2017
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Gaurav Bharti, T. Bag, M.V. Sunil Krishna
      The effect of the geomagnetic storm on the equatorial ionization anomaly (EIA) and equatorial temperature anomaly (ETA) has been studied using the atomic oxygen dayglow emissions at 577.7 nm (OI 557.7 nm) and 732.0 nm (OII 732.0 nm). For the purpose of this study, four intense geomagnetic storms during the ascending phase of solar cycle 24 have been considered. This study is primarily based on the results obtained using photochemical models with necessary inputs from theoretical studies and experimental observations. The latest reaction rate coefficients, quantum yields and the corresponding cross-sections have also been incorporated in these models. The volume emission rate of airglow emissions has been calculated using the neutral densities from NRLMSISE-00 and charged densities from IRI-2012 model. The modeled volume emission rate (VER) for OI 557.7 nm shows a positive correlation with the Dst index at 150 km and negative correlation with Dst at 250 and 280 km altitudes. Latitudinal profile of the greenline emission rate at different altitudes show a distinct behaviour similar to what has been observed in EIA with crests on either sides of the equator. The EIA crests are found to show poleward movement in the higher altitude regions. The volume emission rate of 732.0 nm emission shows a strong enhancement during the main phase of the storm. The changes observed in the airglow emission rates are explained with the help of variations induced in neutral densities and parameters related to EIA and ETA. The latitudinal variation of 732.0 nm emission rate is correlated to the variability in EIA during the storm period.

      PubDate: 2017-12-26T18:25:06Z
      DOI: 10.1016/j.jastp.2017.12.014
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