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  Subjects -> METEOROLOGY (Total: 86 journals)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 4)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 10)
Advances in Climate Change Research     Open Access   (Followers: 1)
Advances in Meteorology     Open Access   (Followers: 9)
Aeolian Research     Hybrid Journal   (Followers: 3)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 8)
American Journal of Climate Change     Open Access   (Followers: 8)
Asian Journal of Earth Sciences     Open Access   (Followers: 21)
Atmósfera     Open Access  
Atmosphere     Open Access   (Followers: 4)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 6)
Atmospheric Chemistry and Physics (ACP)     Open Access   (Followers: 14)
Atmospheric Chemistry and Physics Discussions (ACPD)     Open Access   (Followers: 7)
Atmospheric Research     Hybrid Journal   (Followers: 21)
Atmospheric Science Letters     Open Access   (Followers: 9)
Boundary-Layer Meteorology     Hybrid Journal   (Followers: 10)
Bulletin of the American Meteorological Society     Open Access   (Followers: 17)
Carbon Balance and Management     Open Access   (Followers: 5)
Change and Adaptation in Socio-Ecological Systems     Open Access   (Followers: 1)
Climate     Open Access   (Followers: 3)
Climate Change Economics     Hybrid Journal   (Followers: 16)
Climate Change Responses     Open Access   (Followers: 1)
Climate Dynamics     Hybrid Journal   (Followers: 16)
Climate law     Hybrid Journal   (Followers: 5)
Climate of the Past (CP)     Open Access   (Followers: 5)
Climate of the Past Discussions (CPD)     Open Access   (Followers: 3)
Climate Policy     Hybrid Journal   (Followers: 29)
Climate Risk Management     Open Access   (Followers: 1)
Climate Summary of South Africa     Full-text available via subscription   (Followers: 1)
Climatic Change     Hybrid Journal   (Followers: 41)
Current Climate Change Reports     Hybrid Journal   (Followers: 1)
Developments in Atmospheric Science     Full-text available via subscription   (Followers: 5)
Dynamics and Statistics of the Climate System     Open Access  
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 2)
Earth Perspectives - Transdisciplinarity Enabled     Open Access   (Followers: 1)
Energy & Environment     Full-text available via subscription   (Followers: 18)
Environmental and Climate Technologies     Open Access   (Followers: 3)
Global Meteorology     Open Access   (Followers: 1)
International Journal of Atmospheric Sciences     Open Access   (Followers: 4)
International Journal of Biometeorology     Hybrid Journal   (Followers: 1)
International Journal of Climate Change Strategies and Management     Hybrid Journal   (Followers: 10)
International Journal of Climatology     Hybrid Journal   (Followers: 15)
International Journal of Image and Data Fusion     Hybrid Journal   (Followers: 1)
Journal of Applied Meteorology and Climatology     Full-text available via subscription   (Followers: 10)
Journal of Atmospheric and Oceanic Technology     Full-text available via subscription   (Followers: 10)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 14)
Journal of Atmospheric Chemistry     Hybrid Journal   (Followers: 2)
Journal of Climate     Full-text available via subscription   (Followers: 30)
Journal of Climatology     Open Access   (Followers: 1)
Journal of Hydrology and Meteorology     Open Access   (Followers: 6)
Journal of Hydrometeorology     Full-text available via subscription   (Followers: 4)
Journal of Integrative Environmental Sciences     Hybrid Journal   (Followers: 4)
Journal of Meteorology and Climate Science     Full-text available via subscription   (Followers: 2)
Journal of Space Weather and Space Climate     Open Access   (Followers: 6)
Journal of the Atmospheric Sciences     Full-text available via subscription   (Followers: 27)
Journal of Weather Modification     Full-text available via subscription  
Large Marine Ecosystems     Full-text available via subscription  
Mathematics of Climate and Weather Forecasting     Open Access   (Followers: 1)
Mediterranean Marine Science     Open Access  
Meteorologica     Open Access  
Meteorological Applications     Hybrid Journal   (Followers: 1)
Meteorologische Zeitschrift     Full-text available via subscription   (Followers: 1)
Meteorology and Atmospheric Physics     Hybrid Journal   (Followers: 5)
Mètode Science Studies Journal : Annual Review     Open Access  
Michigan Journal of Sustainability     Open Access  
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 3)
Monthly Notices of the Royal Astronomical Society Letters     Hybrid Journal   (Followers: 4)
Monthly Weather Review     Full-text available via subscription   (Followers: 14)
Nature Climate Change     Full-text available via subscription   (Followers: 48)
Nature Reports Climate Change     Full-text available via subscription   (Followers: 21)
Open Journal of Modern Hydrology     Open Access   (Followers: 4)
Revista Brasileira de Meteorologia     Open Access   (Followers: 1)
Russian Meteorology and Hydrology     Hybrid Journal   (Followers: 4)
Space Weather     Full-text available via subscription   (Followers: 3)
Studia Geophysica et Geodaetica     Hybrid Journal   (Followers: 1)
Tellus A     Open Access   (Followers: 4)
Tellus B     Open Access   (Followers: 6)
The Cryosphere (TC)     Open Access   (Followers: 3)
The Cryosphere Discussions (TCD)     Open Access   (Followers: 2)
The Quarterly Journal of the Royal Meteorological Society     Hybrid Journal   (Followers: 9)
Theoretical and Applied Climatology     Hybrid Journal   (Followers: 4)
Weather     Hybrid Journal   (Followers: 6)
Weather and Climate Extremes     Open Access   (Followers: 4)
Weather and Forecasting     Full-text available via subscription   (Followers: 4)
Weatherwise     Hybrid Journal   (Followers: 1)
气候与环境研究     Full-text available via subscription   (Followers: 1)
Journal Cover Journal of Atmospheric and Solar-Terrestrial Physics
  [SJR: 1.045]   [H-I: 61]   [14 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1364-6826
   Published by Elsevier Homepage  [2801 journals]
  • Spherical Slepian as a new method for ionospheric modeling in arctic
           region
    • Abstract: Publication date: March 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 140
      Author(s): Hossein Etemadfard, Masoud Mashhadi Hossainali
      From the perspective of the physical, chemical and biological balance in the world, the Arctic has gradually turned into an important region opening ways for new researchers and scientific expeditions. In other words, various researches have been funded in order to study this frozen frontier in details. The current study can be seen in the same milieu where researchers intend to propose a set of new base functions for modeling ionospheric in the Arctic. As such, to optimize the Spherical Harmonic (SH) functions, the spatio-spectral concentration is applied here using the Slepian theory that was developed by Simons. For modeling the ionosphere, six International GNSS Service (IGS) stations located in the northern polar region were taken into account. Two other stations were left out for assessing the accuracy of the proposed model. The adopted GPS data starts at DOY 69 (Day of Year) and ends at DOY 83 (totally 15 successive days) in 2013. Three Spherical Slepian models respectively with the maximal degrees of K=15, 20 & 25 were used. Based on the results, K=15 is the optimum degree for the proposed model. The accuracy and precision of the Slepian model are about 0.1 and 0.05 TECU, respectively (TEC Unit=1016 electron/m2). To understand the advantage of this model, it is compared with polynomial and trigonometric series which are developed using the same set of measurements. The accuracy and precision of trigonometric and polynomial models are at least 4 times worse than the Slepian one.
      Graphical abstract image

      PubDate: 2016-02-08T20:52:51Z
       
  • IFC-Ed. board
    • Abstract: Publication date: February 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 138–139




      PubDate: 2016-02-08T20:52:51Z
       
  • Effect of auroral substorms on the ionospheric range spread-F enhancements
           
    • Abstract: Publication date: Available online 2 February 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Lech A. Hajkowicz
      A comprehensive study has been undertaken on the effect of magnetic substorm onsets (as deduced from the auroral hourly electrojet AE- index ) on the occurrence of high midlatitude (or sub-auroral latitude) ionospheric range spread-F (Sr). Unlike the previous reports real- time ionograms were used in this analysis thus eliminating ambiguities stemming from the correlating secondary evidence of spread-F with auroral substorms. The Australian southernmost ionosonde station Hobart (51.6°S geom.) proved to be uniquely suitable for the task as being sufficiently close to the southern auroral zone. Sr was assigned in km to each hourly nighttime ionogram at two sounding frequencies: Sr1 (at 2MHz) and Sr2 (at 6MHz) for four months in 2002: January and June (representing southern summer and winter solstices), and March and September (representing autumn and vernal equinoxes). It is evident that the southern winter solstitial period (June) is associated with high endemic midlatitude spread-F activity. All other seasons are closely linked with temporal sequences of enhanced spread-F activity following substorm onsets. For the first time it was possible not only find a simultaneous occurrence pattern of these diverse phenomena but to deduce numerical characteristics of the response of midlatitude ionosphere to the global auroral stimulus. Excellent case events, hitherto unpublished, are shown illustrating the presence of the AE peaks (in nT) being ahead of Sr peaks (in km) by a time shift ∆t (in hours). Sr1 magnitude showed a significant correlation with the magnitudes of the preceding AE with a correlation coefficient (r) of 0.51 (probability of the occurrence by chance less than 0.01). Sr2 peaks were more sensitive to auroral disturbances but were not correlated with the AE magnitude variations. The time shift (∆t) was on average 4h with a standard deviation of 3h. The general pattern in the occurrence of magnetic substorms and spread-F is very similar. A number of corresponding peaks of the AE-index and Sr fluctuations were identified. The sub-auroral ionosphere response tends to last longer than the initiating auroral disturbance (hysteresis effect). The simultaneous quiescent periods in the auroral and sub-auroral ionospheres have been encountered on at least 14 days.


      PubDate: 2016-02-08T20:52:51Z
       
  • The role of climatic forcings in variations of Portuguese temperature: A
           comparison of spectral and statistical methods
    • Abstract: Publication date: Available online 6 February 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Anna L. Morozova, Tatiana V. Barlyaeva
      Monthly series of temperature parameters measured by three Portuguese meteorological stations from 1888 to 2001 were used to study the effect of different climatic forcings. Three types of external forcings were considered: anthropogenic greenhouse gases and aerosols, volcanic aerosols, and solar and geomagnetic activity variations. Long-term variations of the temperature and other parameters with characteristic periods of decades were studied by various methods including the seasonal-trend decomposition based on LOESS (LOcally wEighted regreSSion), correlation and multiple regression analyses, and wavelet/wavelet coherence analyses. Obtained results confirm the statistical dependence of the temperature variations on the volcanic and the anthropogenic influence as well as variability that can be associated with the solar activity impact. In particular, surprisingly strong bi-decadal cycles were observed in temperature series whereas the observed decadal cycles are weaker and transient. Another interesting finding is the apparent non-stationarity of the relations between the solar and atmospheric parameters probably related to periods of strong/weak global circulation or frequent/occasional volcanic eruptions or interaction between the external forcing and internal atmospheric variability.


      PubDate: 2016-02-08T20:52:51Z
       
  • Corrigendum to “Summer time Fe depletion in the Antarctic mesopause
           region” [J. Atmos. Sol.–Terr. Phys.
           127(2015)97–102]
    • Abstract: Publication date: Available online 5 February 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): T.P. Viehl, J. Höffner, F.-J. Lübken, J.M.C. Plane, B. Kaifler, R.J. Morris



      PubDate: 2016-02-08T20:52:51Z
       
  • Atmospheric changes observed during April 2015 Nepal earthquake
    • Abstract: Publication date: March 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 140
      Author(s): Nandita D. Ganguly
      A massive earthquake shook Nepal on 25 April 2015, with a moment magnitude of 7.9Mw, its hypocenter at a depth of 10km. Atmospheric changes that precede an earthquake might offer the hope of early warning and evacuation. Although the existence of such precursory signals is highly controversial, an attempt has been made to investigate the atmospheric changes from two months prior, to five months following this deadly earthquake. Aerosol optical depth (AOD) and columnar ozone were found to be higher by 40% and 6% respectively prior to the occurrence of the earthquake. The UV aerosol index (UVI), AOD and columnar NO2 increased, while columnar ozone and sea level pressure dropped following the earthquake.


      PubDate: 2016-02-08T20:52:51Z
       
  • Mesospheric signatures observed during 2010 minor stratospheric warming at
           king Sejong station (62° S, 59° W)
    • Abstract: Publication date: Available online 6 February 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): S. Eswaraiah, Yong Ha Kim, Junseok Hong, Jeong-Han Kim, M. Venkat Ratnam, A. Chandran, S.V.B. Rao, Dennis Riggin
      A minor stratospheric sudden warming (SSW) event was noticed in the southern hemisphere (SH) during September (day 259) 2010 along with two episodic warmings in early August (day 212) and late October (day 300) 2010. Among the three warming events, the signature of mesosphere response was detected only for the September event in the mesospheric wind dataset from both meteor radar and MF radar located at King Sejong Station (62°S, 59°W) and Rothera (68°S, 68°W), Antarctica, respectively. The zonal winds in the mesosphere reversed approximately a week before the September SSW event, as has been observed in the 2002 major SSW. Signatures of mesospheric cooling (MC) in association with stratospheric warmings are found in temperatures measured by the Microwave Limb Sounder (MLS). Simulations of specified dynamics version of Whole Atmosphere Community Climate Model (SD-WACCM) are able to reproduce these observed features. The mesospheric wind field was found to differ significantly from that of normal years probably due to enhanced planetary wave (PW) activity before the SSW. From the wavelet analysis of wind data of both stations, we find that strong 14−16 day PWs prevailed prior to the SSW and disappeared suddenly after the SSW in the mesosphere. Our study provides evidence that minor SSWs in SH can result in significant effects on the mesospheric dynamics as in the northern hemisphere.


      PubDate: 2016-02-08T20:52:51Z
       
  • A case study of A mesoscale gravity wave in the MLT region using
           simultaneous multi-instruments in Beijing
    • Abstract: Publication date: Available online 28 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Mingjiao Jia, Xianghui Xue, Xiankang Dou, Yihuan Tang, Chao Yu, Jianfei Wu, Jiyao Xu, Guotao Yang, Baiqi Ning, Lars Hoffmann
      In this work, we used observational data from an all-sky airglow imager at Xinglong (40.2°N, 117.4°E), a sodium lidar at Yanqing (40.4°N, 116.0°E) and a meteor radar at Shisanling (40.3°N, 116.2°E) to study the propagation of a mesoscale gravity wave. During the night of March 1, 2011, the imager identified a mesoscale gravity wave structure in the OH airglow that had a wave period of 2hours, propagated along an azimuthal direction (clockwise) with an angle of 163°, a phase speed of 73m/s, and a horizontal wavelength of 566km. Simultaneous measurements provided by the sodium lidar also showed a perturbation in the sodium layer with a 2-hour period. Based on the SABER/TIMED and radar data, we estimated that the momentum flux and the energy flux of the gravity wave were approximately 0.59m2/s2 and 0.22mW/m2, respectively. Ray-tracing analysis showed that the gravity wave was likely generated in the center of Lake Baikal owing to the existence of a jet- front system in the upper troposphere at that time.


      PubDate: 2016-01-28T20:11:43Z
       
  • Trends of ionospheric irregularities over African low latitude region
           during quiet geomagnetic conditions
    • Abstract: Publication date: Available online 27 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Patrick Mungufeni, John Bosco Habarulema, Edward Jurua
      The occurrence patterns of ionospheric irregularities during quiet geomagnetic conditions over the African low latitude region were analysed. GNSS-derived Total Electron Content of the ionosphere data during the period 2001–2012 were used. The data were obtained from Libreville, Gabon (0.35°N, 9.68°E, geographic, 8.05°S, magnetic), Mbarara, Uganda (0.60°S, 30.74°E, geographic, 10.22°S, magnetic), and Malindi, Kenya (2.99°S, 40.19°E, geographic, 12.42°S, magnetic). The rate of change of total electron content index greater than 0.5TECU/Min were considered as severe ionospheric irregularities. For most of the time, the strength of ionospheric irregularities in March equinox were greater than those during September equinox over East Africa and an opposite observation was made over West Africa. These asymmetries might be due to the direction of the meridional winds during equinoxes over the different stations. Severity of ionospheric irregularity reduced from west towards the east. This might have been related to the decreasing geomagnetic field strength from east towards the west. This is the first study that reveals the equinoctial asymmetry is different in the West and East African sectors. Moreover, the importance of this study lies in the fact that it has used extensive data to examine the isolated and un-explained earlier observations of equinoctial asymmetry and longitudinal variation of ionospheric irregularities over the African low latitude region.


      PubDate: 2016-01-28T20:11:43Z
       
  • Solar Daily Variation at Geomagnetic Observatories in Pakistan
    • Abstract: Publication date: Available online 26 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Rahim Zain, Kumbher Abdul Salam
      A study of solar daily variation is performed using the famous Chapman-Miller method for solar cycles 22 & 23 (1986-2007). The objective is to study the characteristics of Sq variation at Pakistani geomagnetic observatories using solar harmonics and a more traditional five quietest day's method. The data recorded at the Karachi geomagnetic observatory for SC 22 and 23 and data sets from other Pakistani geomagnetic observatories; Sonmiani, Quetta and Islamabad are analyzed for H, D and Z components of the geomagnetic field. Except for the D and Z components at Karachi and Sonmiani and H component at Islamabad, the two solar daily variations correlated well with each other. Also, the synthesized daily variation from the solar harmonics of H, D and Z components explained the equivalent Sq current system reasonably well for all seasons. For H component, the first solar harmonic (s1) obtained from spherical harmonic analysis of the data, appeared as the largest harmonic with no significant changes for the seasonal division of data. However, for D and Z components, amplitudes are comparable, but undergo distinct variations. s1 for H and D components increases with magnetic activity while for Z component it is the largest for the medium phase of magnetic activity. With the sunspot number division of data, the weighted mean of the Wolf ratio of all three components is in good agreement with the previous studies. The synthesized solar daily variation for D component, S(D), at Karachi, Sonmiani, Quetta and Islamabad did not show any signs of winter anomaly for the period studied. However, S(D) variation at Karachi during winter season showed morning minimum followed by a maximum at local noon and another minimum in the afternoon. We suggest this could be the effects of Equatorial Ionospheric Anomaly (EIA) observable at the Karachi observatory only during the winter season. Similarly, much disturbed in equinoctial and summer months, S(Z) illustrated an unwavering daily variation for the winter season at the Karachi observatory for both solar cycles. We find that it is the vertical component which is more strongly correlated with the mean monthly sunspot number and F10.7 solar radio flux. An interesting result obtained at Islamabad is the semi-diurnal variation of H component with a morning maximum and afternoon minimum and the phase reversal noticed for Z component variation. Attributed to an early eastward current this is, usually, observed for stations close to the Sq focus current system.


      PubDate: 2016-01-28T20:11:43Z
       
  • On the nature of IMF polarity dependent asymmetries in solar wind plasma
           properties during the minimum of sunspot cycles 23 and 24
    • Abstract: Publication date: Available online 22 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Felix Pereira B, Bijoy John Philip, Girish T. E
      The monthly solar wind speed and density observed near 1AU in IMF sectors of opposite magnetic polarity are studied during the minimum of sunspot cycles 23 and 24. During sunspot minima, the IMF is pointing away from the sun (Away sector) in the north of the Heliospheric Current Sheet (HCS) and pointing towards the sun (Toward sector) in the south of HCS during odd sunspot cycles and the same process is reversed during the even cycles. During this period, the solar wind plasma parameters (number density and speed) show a systematic month to month variation with solar wind number density decreases and velocity increases from equator to poles (heliomagnetic latitudinal organization) only in ‘Away’ IMF sectors compared to ‘Toward’ IMF sectors. This feature is particularly more evident for low speed solar wind and happens in a helio-hemisphere with a larger polar coronal hole. The association of the above phenomena with north-south asymmetry in coronal and solar wind flow characteristics will be discussed.


      PubDate: 2016-01-23T20:03:28Z
       
  • Investigation of gravity wave activity based on operational radiosonde
           data from 13 years (1997-2009): Climatology and possible induced
           variability
    • Abstract: Publication date: Available online 23 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): R. Kramer, S. Wüst, M. Bittner
      Atmospheric gravity waves (GWs) are important for the dynamics of the atmosphere. The analysis of 13 years of routine radiosonde data from Prague (50.01°N, 14.27°E) with temporal highly resolved temperature, pressure and wind measurements is presented in order to derive a climatology of gravity wave activity in the lower stratosphere. An annual cycle with a maximum during winter and a minimum during summer is identified. Gravity wave activity is twice as high during winter as during summer. Winter periods are investigated by wavelet analysis. They show similar periods in vertical flux of horizontal momentum and pressure variance time series. These features may be attributed to planetary waves. When analyzing individual years, maxima of gravity wave activity and vertical flux of horizontal momentum often appears together with minima in surface pressure. We speculate therefore that at least parts of the interannual variations of gravity wave activity may due to cyclones.


      PubDate: 2016-01-23T20:03:28Z
       
  • Simulating electron and ion temperature in a global ionosphere
           thermosphere model: Validation and modeling an idealized substorm
    • Abstract: Publication date: Available online 15 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Jie Zhu, Aaron J. Ridley, Yue Deng
      Electron and ion temperatures control many chemical and physical processes in the ionosphere–thermosphere system. Recently, improved electron and ion energy equations were implemented in the Global Ionosphere Thermosphere Model (GITM). The source energy of the electron temperature (T e ) includes thermal conduction, heating due to photoionization, elastic collisions with ions, elastic and inelastic collisions with neutrals, auroral precipitation, and heat flux from inner magnetosphere. The source terms in the ion temperature (T i ) equation include thermal conduction, and elastic collisions with electrons and neutrals. The new implementation of T e improved the ionospheric density at middle and high latitudes with respect to IRI. The improved GITM also reproduced the diurnal variation in T e and T i observed by incoherent scatter radars at low and middle latitudes. The model was used to investigate an idealized substorm statistically described by Clausen et al. (2014). It was found that the responses of the E-region N e and T e were highly correlated with the variation in auroral hemispheric power. The change of the F-region T e was correlated with the E-region T e and N e , which was consistent with observations. The response of the F-region N e to the particle precipitation was delayed by about 30min, and lasted significantly longer than the enhanced precipitation. The variations of T i in both the E- and F-regions were dominated by IMF-driven ion drifts through frictional energy coupling with the neutrals. It was also found that the increase of the mid-latitude heat flux by one order of magnitude enhanced T e , electron density and TEC by up to 120%, 80% and 80% respectively between dusk and midnight.


      PubDate: 2016-01-18T19:51:39Z
       
  • Towards Climatological study on the characteristics of aerosols in central
           Africa and mediterranean sites
    • Abstract: Publication date: Available online 16 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Jamel Benkhalifa, Mabrouk Chaabane
      The atmosphere contains molecules, clouds and aerosols that are sub-millimeter particles having a large variability in size, shape, chemical composition, lifetime and contents. The aerosols concentration depends greatly on the geographical situation, meteorological and environmental conditions, which makes aerosol climatology difficult to assess. Setting up a solar photometer (automatic, autonomous and portable instrument) on a given site allows carrying out the necessary measurements for aerosol characterization. The particle microphysical and optical properties are obtained from photometric measurements. The objective of this study is to analyze the spatial variability of aerosol optical thickness (AOT) in several Mediterranean regions and Central Africa, we considered a set of simultaneous data in the AErosol RObotic NETwork (AERONET) from six sites, two of which are located in Central Africa (Banizoumbou and Zinder Airport) and the rest are Mediterranean sites (Barcelona, Malaga, Lampedusa, and Forth Crete). The results have shown that the physical properties of aerosols are closely linked to the climate nature of the studied site. The optical thickness, single scattering albedo and aerosols size distribution can be due to the aging of the dust aerosol as they are transported over the Mediterranean basin.


      PubDate: 2016-01-18T19:51:39Z
       
  • On the influence of the urban heat island on the cooling load of a school
           building in Athens, Greece
    • Abstract: Publication date: Available online 14 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): H. Bagiorgas, G. Mihalakakou
      The present study investigates the effect of the urban heat island (UHI) phenomenon, measured in the Greater Athens Area (GAA), on the energy consumption of a typical modern school building. The energy performance of the selected building has been calculated using an accurate, extensively validated, transient simulation model for 17 different sites of the GAA, for the summer period. Calculations showed that the urban heat island phenomenon affects remarkably the thermal behavior of the school building, as suburban areas presented much lower cooling loads. The cooling load values fluctuated between 3304.3kWh for the rural stations and 14585.1kWh for the central stations (for the year 2011) or between 3206.5kWh and 14208.3kWh (for the year 2012), respectively. Moreover, the mean monthly cooling load values varied between 0.4–2kWh/m2 for the rural stations and 4–6.9kWh/m2 for the central stations, for the selected time period. Furthermore, a neural network model was designed and developed in order to quantify the contribution of various meteorological parameters (such as the mean daily air temperature values, the mean daily solar radiation values, the average wind speed and the urban heat island intensity) to the energy consumption of the building and it was found that the urban heat island intensity is the predominant parameter, influencing remarkably the energy consumption of the typical school building.


      PubDate: 2016-01-15T19:31:11Z
       
  • Ionospheric F2 layer responses to total solar eclipses at low and
           mid-latitude
    • Abstract: Publication date: Available online 13 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): B.J. Adekoya, V.U. Chukwuma
      In this article, we presented ionospheric F2 responses to total solar eclipses on the basis of the data obtained from five (5) equatorial/low-latitude and twenty-seven (27) mid-latitude ionosonde stations, which are within the obscuration percentage of 50-100% of the path of the total solar eclipses progression. Statistically, the diurnal changes in the F2 layer peak height hmF2 and electron density NmF2, as well as the latitudinal and hemispheric dependence and the contribution of both magnetic and solar activities during the eclipse window were investigated. The estimation of the solar ionizing radiation that remains unmasked during the eclipse window was as well carried out. Plasma diffusion processes dominate the F2 region plasma, and determine the height at which the F2 peak formed at mid-latitude. The electron density decreased during the eclipse window, closely following the variation in the local solar radiation at the mid-latitude. However, at equatorial/low-latitude, the plasma distribution during total solar eclipse depends on combine effect of solar radiation and the background nighttime ionospheric irregularities mechanism. The uncertainty level of the estimated solar ionizing radiation was<± 0.3 at mid-latitude and greater±0.3 at equatorial/low-latitude. Their correlation ranges from (0.42-0.99). The ionospheric F2 layer eclipse effect is latitudinal and hemispheric dependent. The effect is largest at mid-latitude and relatively small at equatorial/low-latitudes. It is more pronounced at the equator, and decreases toward the equatorial ionospheric anomaly (EIA) region. The better correlation of 0.5840 and 0.6435 between geographic latitude and E (t) and electron density justifies the latitudinal relationship. The increase in percentage deviation of electron density increases with latitude and delay time (∆T) in the northern hemisphere of the mid-latitude. Conversely, in the southern hemisphere the percentage deviation decreases with an increase in ∆T and the latitude. The influence of the combined effect of solar activity and magnetic disturbances cannot the overlooked during total solar eclipse. At the eclipse shadow, the deviation increases with decreasing magnetic disturbances and solar activity. During magnetic quiet conditions the variation in maximum NmF2/hmF2 on the eclipse day are more decrease/increase than the control day and overturned during the magnetic disturbed condition.


      PubDate: 2016-01-15T19:31:11Z
       
  • Radiative Analysis of Global Mean Temperature Trends in the Middle
           Atmosphere: Effects of Non-Locality and Secondary Absorption Bands
    • Abstract: Publication date: Available online 14 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): V.I. Fomichev, A.I. Jonsson, W.E. Ward
      In this paper, we provide a refined and extended assignment of past and future temperature changes relative to previous analyses and describe and evaluate the relevance of vertical coupling of, non-linear and secondary radiative mechanisms for the interpretation of climatic temperature variations in the middle atmosphere. Because of their nature, the latter mechanisms are not adequately accounted for in most regression analyses of temperature trends as a function of local constituent variations. These mechanisms are examined using 1) globally averaged profiles from transient simulations with the Canadian Middle Atmosphere Model (CMAM) forced by changes in greenhouse gases and ozone depleting substances and 2) a one-dimensional radiative-equilibrium model forced using the diagnosed global mean changes in radiatively active constituents as derived from the CMAM model runs. The conditions during the periods 1975 to 1995 and 2010 to 2040 (during which the rates of change in ozone and CO2 differ) provide a suitable contrast for the role of the non-linear and non-local mechanisms being evaluated in this paper to be clearly differentiated and evaluated. Vertical coupling of radiative transfer effects and the influence of secondary absorption bands are important enough to render the results of multiple linear regression analyses between the temperature response and constituent changes misleading. These effects are evaluated in detail using the 1D radiative-equilibrium model using profiles from the CMAM runs as inputs. In order to explain the differences in the CMAM temperature trends prior to and after 2000 these other radiative effects must be considered in addition to local changes in the radiatively active species. The middle atmosphere temperature cools in response to CO2 and water vapor increases, but past and future trends are modulated by ozone changes.


      PubDate: 2016-01-15T19:31:11Z
       
  • Long-term variation of OH peak emission altitude and volume emission rate
           over indian low latitudes
    • Abstract: Publication date: Available online 15 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): M. Sivakandan, T.K. Ramkumar, A. Taori, Venkateshwara Rao, K. Niranjan
      Using 13 (April 2002 –December 2014) years of Sounding of the Atmosphere using Broadband Emission Radiometry (SABER/TIMED) 1.6µm OH airglow emission data, we have studied the long-term variation of OH peak emission altitude and volume emission rate (VER) for 0–10° N latitude and 70–90° E longitude grid. We have noted that, during day time the OH peak emission altitude is varying from 80 to 87km with mean value of 83.5km and from 82 to 88km with mean value of 85km during night time. The signature of semi-annual oscillation (SAO), annual oscillation (AO) and quasi-biennial oscillation (QBO) in the OH peak emission altitude as well as the VER is evident. Our analysis reveals that the SAO and QBO signatures but not the AO signature are very strong in the equatorial region during night time. Apart from the SAO, AO and QBO signatures, the presence of oscillation related to the El Niño oscillation (ENSO) is also noted. After the removal of these oscillations, we find the evidence of the influence of solar activity and a long term trend in the OH emission layer. It is also found good correlation between the mesospheric and stratospheric variations (ECMWF data).


      PubDate: 2016-01-15T19:31:11Z
       
  • Re-visit of ionosphere storm morphology with TEC data in the current solar
           cycle
    • Abstract: Publication date: Available online 12 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Ljiljana R. Cander
      This paper addresses the magnetosphere-ionosphere-thermosphere (M-I-T) storm effects, with emphasis on 15 major geomagnetic storms in the current solar cycle as far as May 2015. It is an ionosphere storm response-case analysis based on the vertical total electron content (VTEC) observations at mid-latitude Global Positioning System (GPS) ground-based station HERS (0.33°E, 50.86°N). The time dependent features of ionospheric storms are examined with ∆VTEC defined as the percent change of VTEC during storm time relative to quiet time represented by its monthly median value at the same UT. During a specific event of April 2010 storm, the F2 layer peak electron density (NmF2) data at collocated Chilton (358.67°E, 51.70°N) ionosonde station are used for comparison. The seasonal dependence of the storms is identified and the strength of both positive and negative storms phases is correlated with the intensity of the geomagnetic storms. The focus is on localized characteristics of these solar-terrestrial disturbances and the relative roles of inherent physical and chemical processes that appear to be so changeable from one event to the other generating significant variability in ionospheric responses. The implications of these results for the persistence, certainty and consequently predictability of ionosphric storms are discussed and conclusions drown.


      PubDate: 2016-01-15T19:31:11Z
       
  • Pattern of aerosol mass loading and chemical composition over the
           atmospheric environment of an urban coastal station
    • Abstract: Publication date: Available online 8 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): G Bindu, Prabha R Nair, S Aryasree, Prashant Hegde, Salu Jacob
      Aerosol sampling was carried out at four locations in and around Cochin (9°58’ N, 76°17’E), an urban area, located on the southwest coast of India. The gravimetric estimates of aerosol mass loading showed wide range from 78 µg m-3 to >450 µg m-3, occasionally reaching values >500 µg m-3, associated with regional source characteristics. Most of the values were above the air quality standard. Both boundary layer and synoptic scale airflow pattern play role in the temporal features in aerosol mass loading and chemical composition. Chemical analysis of the aerosol samples were done for anionic species viz; F-, Cl-, Br-, NO2 -, NO3 -, PO4 3-, SO4 2 - and metallic/cationic species viz; Na, Ca, K, Mg, NH4 +, Fe, Al, Cu, Mg, Pb, etc using Ion Chromatography, Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma- Atomic Emission Spectroscopy (ICP-AES). At all the locations, extremely high mass concentration of SO4 2- was observed with the mean value of 13±6.4 µg m-3 indicating the strong anthropogenic influence. Statistical analysis of the chemical composition data was carried out and the principal factors presented. Seasonal variation of these chemical species along with their percentage contributions and regional variations were also examined. Increase in level of Na in aerosol samples indicated the influence of monsoonal activity. Most of the species showed mass concentrations well above those measured over another coastal site Thiruvananthapuram (8°29’N, 76°57’E) situated ~220km south of Cochin revealing the highly localized aerosol features.


      PubDate: 2016-01-11T19:24:55Z
       
  • Global ionospheric flare detection system (GIFDS)
    • Abstract: Publication date: Available online 8 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Daniela Wenzel, Norbert Jakowski, Jens Berdermann, Christoph Mayer, Cesar Valladares, Bernd Heber
      The Global Ionospheric Flare Detection System (GIFDS) is currently under development at the German Aerospace Center as a ground based detector for continuous monitoring of the solar flare activity in order to provide real time warnings on solar X-ray events. GIFDS is using Very Low Frequency (VLF) radio transmissions in the northern hemisphere which respond to enhanced ionization in the bottomside ionosphere caused by X-ray flares. Since solar flares can only be detected during daytime, VLF receivers have to be installed around the globe to guarantee continuous records at the dayside sector. GIFDS consists of a network of Perseus SDR (Software Defined Radio) receivers equipped with a MiniWhip antenna each. Reliable detection of solar flares is ensured by recording multiple frequency channels ranging from 0 to 500kHz. The applicability of the system is demonstrated in a first analysis by comparing VLF measurements with GOES's (Geostationary Operational Environmental Satellite) X-ray flux data. The high potential of GIFDS for a permanent monitoring of solar flares in near real time is discussed.


      PubDate: 2016-01-11T19:24:55Z
       
  • Latin American Lidar Network (LALINET) for aerosol research: Diagnosis on
           network instrumentation
    • Abstract: Publication date: Available online 6 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Juan Luis Guerrero-Rascado, Eduardo Landulfo, Juan Carlos Antuña, Henrique de Melo Jorge Barbosa, Boris Barja, Álvaro Efrain Bastidas, Andrés Esteban Bedoya, Renata Facundes da Costa, René Estevan, Ricardo Forno, Diego Alvés Gouveia, Cristofer Jiménez, Eliane Gonçalves Larroza, Fábio Juliano da Silva Lopes, Elena Montilla-Rosero, Gregori de Arruda Moreira, Walker Morinobu Nakaema, Daniel Nisperuza, Dairo Alegria, Mauricio Múnera, Lidia Otero, Sebastián Papandrea, Juan Vicente Pallota, Ezequiel Pawelko, Eduardo Jaime Quel, Pablo Ristori, Patricia Ferrini Rodrigues, Jacobo Salvador, Maria Fernanda Sánchez, Antonieta Silva
      LALINET (Latin American Lidar Network), previously known as ALINE, is the first fully operative lidar network for aerosol research in South America, probing the atmosphere on regular basis since September 2013. The general purpose of this network is to attempt to fill the gap in the knowledge on aerosol vertical distribution over South America and its direct and indirect impact on weather and climate by the establishment of a vertically-resolved dataset of aerosol properties. Similarly to other lidar research networks, most of the LALINET instruments are not commercially produced and, consequently, configurations, capabilities and derived-products can be remarkably different among stations. It is a fact that such un-biased 4D dataset calls for a strict standardization from the instrumental and data processing point of view. This study has been envisaged to investigate the ongoing network configurations with the aim of highlighting the instrumental strengths and weaknesses of LALINET.


      PubDate: 2016-01-07T19:20:58Z
       
  • ON THE CHARACTERISTICS OF POSITIVE LIGHTNING GROUND FLASHES IN SWEDEN
    • Abstract: Publication date: Available online 4 January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Zikri Abadi Baharudin, Vernon Cooray, Mahbubur Rahman, Pasan Hettiarachchi, Noor Azlinda Ahmad
      In this study the stroke characteristics of positive cloud-to-ground flashes in Sweden were obtained from the electric field records measured from 14 thunderstorms. The electric fields were measured with nanosecond resolution. Together with the fast and the slow electric field records, the narrowband radiation field at 3 and 30MHz signals were also measured simultaneously. Out of a total of 107 flashes, 30 flashes had two strokes, 7 had three strokes and 3 flashes had four strokes. The arithmetic and geometric means of the interstroke intervals were found to be 116 and 70 ms, respectively. The arithmetic and geometric mean ratio between the peak electric field of the Subsequent Return Stroke (SRS) and the first Return Stroke (RS) were 0.48 and 0.36, respectively. Of the 40 positive multiple-stroke ground flashes, 5% have at least one SRS with field peak higher than the first RS. The percentage of SRS with field peaks greater than the first RS was 6%. In our best of our knowledge, this is the first time a large sample of positive return strokes in Sweden was analysed. It was found to be statistically more significant than the previous studies.
      Graphical abstract image

      PubDate: 2016-01-07T19:20:58Z
       
  • sEffects of the intense geomagnetic storm of September-October 2012 on the
           equatorial, low- and mid-latitude F region in the American and African
           sector during the unusual 24th solar cycle
    • Abstract: Publication date: Available online 30 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): R. de Jesus, P.R. Fagundes, A. Coster, O.S. Bolaji, J.H.A. Sobral, I.S. Batista, A.J. de Abreu, K. Venkatesh, M. Gende, J.R. Abalde, S.G. Sumod
      The main purpose of this paper is to investigate the response of the ionospheric F layer in the American and African sectors during the intense geomagnetic storm which occurred on 30 September – 01 October 2012. In this work, we used observations from a chain of 20 GPS stations in the equatorial, low- and mid-latitude regions in the American and African sectors. Also, in this study ionospheric sounding data obtained during 29th September to 2nd October, 2012 at Jicamarca (JIC), Peru, São Luis (SL), Fortaleza (FZ), Brazil, and Port Stanley (PST), are presented. On the night of 30 September – 01 October, in the main and recovery phase, the h´F variations showed an unusual uplifting of the F region at equatorial (JIC, SL and FZ) and mid- (PST) latitude stations related with the propagations of traveling ionospheric disturbances (TIDs) generated by Joule heating at auroral regions. On 30 September, the VTEC variations and foF2 observations at mid-latitude stations (American sector) showed a long-duration positive ionospheric storm (over 6h of enhancement) associated with large-scale wind circulations and equatorward neutral winds. Also, on 01 October, a long-duration positive ionospheric storm was observed at equatorial, low- and mid- latitude stations in the African sector, related with the large-scale wind circulations and equatorward neutral winds. On 01 and 02 October, positive ionospheric storms were observed at equatorial, low- and mid-latitude stations in the American sector, possibly associated with the TIDs and an equatorward neutral wind. Also, on 01 October negative ionospheric storms were observed at equatorial, low- and mid-latitude regions in the American sector, probably associated with the changes in the O/N2 ratio. On the night of 30 September – 01 October, ionospheric plasma bubbles were observed at equatorial, low- and mid- latitude stations in the South American sector, possibly associated with the occurrence of geomagnetic storm.


      PubDate: 2016-01-03T18:54:41Z
       
  • Ceilometer signal performance with height in high aerosol loads
    • Abstract: Publication date: Available online 29 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): D. Bachour, D. Perez-Astudillo
      This paper is dedicated to the study of the Vaisala CL51 ceilometer backscatter signals during a one-year period, in particular the study of the noise embedded in the signals measured by the ceilometer, under cloudless conditions. The noise analysis is done to provide indication about the maximum atmospheric height up to which the ceilometer signal is still reliable enough in clear-sky conditions, for the detection of changing aerosol contents. The experiment was carried out in Doha, Qatar, for a period of 12 months, from December 2012 to November 2013. 214 clear days were selected during this year. Several tests were performed in order to assess the variability of the backscatter signals from day to day and between different heights in the atmosphere. To the authors' knowledge, it is the first time that the signal performance of a ceilometer is studied in a highly aerosol-loaded region, and for a relatively extended period of time. Considering the whole year, it is found that a height of 5 or 6km represents a good compromise between including the signals arising from the dynamicity of the atmosphere and removing as much as possible the signal dominated by noise at higher heights. In winter months, however, this limit can be extended up to a height of 7km.


      PubDate: 2016-01-03T18:54:41Z
       
  • Mid-latitude atmosphere and ionosphere connection as revealed by very low
           frequency signals
    • Abstract: Publication date: Available online 30 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Sujay Pal, Yasuhide Hobara
      Quantitative information about the effect of atmospheric influences on the variability of upper mesosphere–lower ionosphere (UMLI) region is not clearly known yet. To investigate the relationship between the lower atmosphere and UMLI region, we compared the amplitude of very low frequency (VLF) signals with the atmospheric parameters such as total column Ozone (TCO) density and stratospheric temperature at various heights for the first time for three different latitudinal regions. We show that the VLF amplitude is strongly correlated with the TCO density, stratospheric temperatures for mid-latitude propagation paths throughout the years. For high and low latitude regions, this correlation between the VLF amplitude and atmospheric parameters is poor and not significant. This study indicates the experimental observation of latitudinal dependence of atmospheric influence on the upper mesosphere.


      PubDate: 2016-01-03T18:54:41Z
       
  • Comparison of Maximum Usable Frequency (MUF) Variability over Peninsular
           Malaysia with IRI model during the rise of Solar Cycle 24
    • Abstract: Publication date: Available online 29 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): R.A. Malik, M. Abdullah, S. Abdullah, M.J. Homam
      The aim of this paper is to study maximum usable frequency (MUF) variability over Peninsular Malaysia (112.5°E, 2.5°N) which is located in the equatorial region during the rise of Solar Cycle 24 (2009–2011). The MUF Test data was obtained from high frequency (HF) transmission tests that were conducted from April 2009 to September 2011. Relative variability VR was used to compute the relative variability of MUF. Variability of diurnal, seasonal and sunspot effect on MUF of test was compared to International Reference Ionosphere (IRI) version of 2012. The results show that: (a) MUF from the IRI model is higher than the MUF Test but the magnitude for the MUF Test and IRI are similar; (b) from the diurnal analysis, MUF is more vulnerable to variability during the nighttime than the daytime where the variability range for MUF Test and IRI during daytime is 4–12% compared to the nighttime range of 10–30%; (c) seasonal variability for MUF Test in 2011 indicates no clear trend for all seasons, and the seasonal and monthly variability for both MUF VR in 2011 is lower compared to 2009 and 2010; and (d) when sunspot number increases, MUF VR decreases. This result complements the variability in the equatorial and low latitude regions in that when solar activity increases, variability decreases.


      PubDate: 2015-12-29T18:28:12Z
       
  • IAR signatures in the ionosphere: Modeling and observations at the
           Chibis-M microsatellite
    • Abstract: Publication date: Available online 23 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): V. Pilipenko, D. Dudkin, E. Fedorov, V. Korepanov, S. Klimov
      A peculiar feature of geomagnetic variations at middle/low latitudes in the ULF band, just below the fundamental tone of the Schumann resonance, is the occurrence of a multi-band spectral resonant structure, observed by high-sensitivity induction magnetometers during nighttime. The occurrence of such spectral structure was commonly attributed to the Ionospheric Alfvén Resonator (IAR) in the upper ionosphere. Rather surprisingly, while ground observations of the IAR are ubiquitous, there are practically no reports on the IAR signatures from space missions. According to the new paradigm, the multi-band spectral structure excited by a lightning discharge is in fact produced by a regular sequence of an original pulse from a stroke and echo-pulses reflected from the IAR upper boundary. Upon the interaction of initial lightning-generated pulse with the anisotropic lower ionosphere, it partially penetrates into the ionosphere, travels up the ionosphere as an Alfvén pulse, and reflects back from the upper IAR boundary. The superposition of the initial pulse and echo-pulses produces spectra with multiple spectral peaks. Our modeling of Alfvénic pulse propagation in a system with the altitude profile of Alfven velocity modeling the realistic ionosphere has shown that IAR spectral signatures are to be evident only on the ground and above the IAR. Inside the IAR, the superposition of upward and downward propagating pulses produces a more complicated spectral pattern and the IAR spectral signatures deteriorate. We have used electric field data from the low-orbit Chibis-M microsatellite to search for IAR signatures in the ionosphere. We found evidence that the multi-band structure revealed by spectral analysis in the frequency range of interest is indeed the result of a sequence of lightning-produced pulses. According to the proposed conception it seems possible to comprehend why the IAR signatures are less evident in the ionosphere than on the ground.


      PubDate: 2015-12-26T18:06:41Z
       
  • Characteristics of Narrow Bipolar Pulses observed from lightning in Sri
           Lanka
    • Abstract: Publication date: Available online 19 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): M. Fernando, U. Sonnadara, V. Cooray, T.A.L.N. Gunasekara
      A detailed study on electric field characteristics of Narrow Bipolar Pulses (NBP) observed in Sri Lanka is presented here. NBPs analyzed in this work were recorded at a coastal location in the Southern part of Sri Lanka (Matara: 5.95°N, 8.53°E), from five highly active consecutive thunderstorm days during the month of May in 2013. The waveforms were recorded with a 10ns resolution within a 100ms time window. Both positive and negative NBPs were observed in this study with the negative type being the most frequent. Parameters presented in this study were the rise time (Tr), zero crossing time (Tz), the duration of slow front (Ts), the full width of half maximum (FWHM), the pulse duration and the ratio of amplitude of overshoot to the corresponding peak amplitude (Os/Pa). The corresponding average values of negative NBPs for these parameters were found to be 0.58µs, 3.01µs, 0.20µs, 1.38µs, 19.21µs and 0.19 respectively. Similarly, for positive events corresponding values were 1.38µs, 4.66µs, 0.48µs, 1.93µs, 16.42µs and 0.37 respectively. The above values conforms to a much narrower bipolar events when compared to previously reported values which is considered to be caused by the propagation effects of signals captured by the apparatus.


      PubDate: 2015-12-22T17:32:55Z
       
  • Changes in the South Asian Monsoon Low Level Jet during recent decades and
           its role in the monsoon water cycle
    • Abstract: Publication date: Available online 17 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): S. Aneesh, S. Sijikumar
      June to September mean wind at 850hPa from ERA-Interim, MERRA and NCEP2 reanalyses show an increasing trend in the south Asian monsoon Low Level Jet (LLJ) during 1980–2014. In the sub-seasonal scale, the LLJ during July and September exhibit increasing trend, while August shows a decreasing trend. Lesser changes in surface pressure over heat low region and weaker Bay of Bengal convection leads to weakening of LLJ during August while an intense heat low during September results stronger LLJ. The associated moisture transport changes affect the monsoon hydrological cycle with decreasing precipitation during August and increasing precipitation during September.


      PubDate: 2015-12-18T04:25:01Z
       
  • Downward propagating Equatorial Annual Oscillation and QBO generated
           multi-year oscillations in stratospheric NCEP reanalysis data
    • Abstract: Publication date: February 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volumes 138–139
      Author(s): Hans G. Mayr, Jae N. Lee
      In this brief review we discuss and summarize the results of an analysis of zonal wind and temperature variations from the National Center for Environmental Prediction (NCEP) reanalysis, which provide observational evidence for the 12-month Equatorial Annual Oscillation (EAO), in addition to the classical equatorial oscillations, the 6-month Semi-annual Oscillation (SAO) and Quasi-biannual Oscillation (QBO). The EAO is observed slowly propagating down with a velocity of about 3km/month in agreement with the results from a numerical model, and characteristic of wave mean flow interactions at low latitudes that generate the QBO at 1.3km/month. For data samples that cover as much as 40 years, the NCEP zonal winds reveal a rich spectrum of oscillations with periods between 3 and 10 years. Such multi-year oscillations can be generated by the QBO interacting with the seasonal variations through wave filtering. As shown with model simulations, the 30-month QBO can interact with the 12-month Annual Oscillation (AO) to generate a 5-year oscillation, which is prominent in the NCEP data. And the 27-month QBO can generate a 9-year quasi-decadal oscillation, which is also observed along with the related modulation signatures close to 3 years.


      PubDate: 2015-12-18T04:25:01Z
       
  • IFC-Ed. board
    • Abstract: Publication date: January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 137




      PubDate: 2015-12-18T04:25:01Z
       
  • Catalogue of electron precipitation events as observed in the
           long-duration cosmic ray balloon experiment
    • Abstract: Publication date: Available online 12 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): V.S. Makhmutov, G.A. Bazilevskaya, Yu.I. Stozhkov, A.K. Svirzhevskaya, N.S. Svirzhevsky
      Since the International Geophysical Year (1957), the Lebedev Physical Institute performs the regular measurements of charged particle fluxes in the Earth's atmosphere (from the ground level up to 30–35km) at several latitudes. The unique experimental data base obtained during 58 years of cosmic rays observations in the atmosphere allows to investigate temporal, spatial and energetic characteristics of galactic and solar cosmic rays as well as the role of charged particles in the atmospheric processes. Analysis of this data base also revealed a special class of numerous events caused by energetic electron precipitation recorded in the atmosphere at polar latitudes. In this paper we present Catalogue of electron precipitation events observed in the polar atmosphere during 1961–2014 and briefly outline the previous results of this data set analysis.


      PubDate: 2015-12-14T17:27:03Z
       
  • Investigations of Mesospheric Temperature Inversions over Sub-tropical
           Location using Lidar and Satellites Measurements
    • Abstract: Publication date: Available online 12 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Som Sharma, H Chandra, G. Beig, Prashant Kumar, Rajesh Vaishnav
      Characteristics of Mesospheric Temperature Inversions (MTIs) are studied using ~290 nights of Rayleigh Lidar data collected over Mt. Abu (24.5°N, 72.7°E) during the period of 1997 to 2004 for the first time from an Indian sub-tropical location. Three MTI events have been investigated and statistical analysis has also been performed. A strong MTI event, with amplitude of about 30K, at altitudes between 60 and 70km was observed on 30 December 2003. It was accompanied by strongly perturbed mesospheric zonal winds as observed by TIMED Doppler Interferometer (TIDI) onboard Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED). Two MTI episodes during March and December 2000 have been investigated, which showed that MTI can persist for few days and its amplitude varies gradually. Ozone observed by Halogen Occultation Experiment (HALOE) onboard Upper Atmospheric Research Satellite (UARS) also showed significantly higher variability during strong MTI events. A statistical analysis of MTI occurrence and their characteristics have been done using Lidar data (1997–2004), HALOE on board UARS (1997–2004) and SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) on board TIMED (2002–2004). The frequency of occurrence of MTIs is maximum during winter and minimum during summer and average magnitude of MTIs is ~20K with prominent seasonal variability. SABER and Lidar observed occurrence statistics is showing very similar pattern and SABER is able to capture stronger MTIs (~50K). The average bottom height of MTIs from Lidar is having strong seasonality (lower height during winter) in contrast to satellites observed heights of MTIs.


      PubDate: 2015-12-14T17:27:03Z
       
  • Low latitude ionospheric scintillation and zonal plasma irregularity
           drifts climatology around the equatorial anomaly crest over Kenya
    • Abstract: Publication date: Available online 9 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): O.J. Olwendo, P. Baki, P.J. Cilliers, P. Doherty, S. Radicella
      In this study we have used a VHF and GPS-SCINDA receiver located at Nairobi (36.8°E, 1.3°S, dip −24.1°) in Kenya to investigate the climatology of ionospheric l-band scintillation occurrences for the period 2009 to 2012; and seasonal variation of the zonal plasma drift irregularities derived from a VHF receiver for the period 2011. The annual and diurnal variations of l-band scintillation indicate occurrence at post sunset hours and peaks in the equinoctial months. However VHF scintillation occurs at all seasons around the year and is characterized by longer duration of activity and a slow fading that continues till early morning hours unlike in the l-band where they cease after midnight hours. A directional analysis has shown that the spatial distribution of scintillation events is mainly on the Southern and Western part of the sky over Nairobi station closer to the edges of the crest of the Equatorial Ionization Anomaly. The distribution of zonal drift velocities of the VHF related scintillation structures indicates that they move at velocities in the range of 20 to 160m/s and their dimension in the East-West direction is in the range of 100 to 900km. The December solstice is associated with the largest plasma bubbles in the range of 600 to 900km. The most significant observation from this study is the occurrence of post- midnight scintillation without pre-midnight scintillations during magnetically quiet periods. The mechanism leading to the formation of the plasma density irregularity causing scintillation is believed to be via the Rayleigh Tailor Instability; it is however not clear whether we can also attribute the post-midnight plasma bubbles during magnetic quiet times to the same mechanism. From our observations in this study, we suggest that a more likely cause of the east ward zonal electric fields at post-midnight hours is the coupling of the ionosphere with the lower atmosphere during nighttime. This however needs a further investigation based on relevant data.


      PubDate: 2015-12-10T17:16:37Z
       
  • Effect of gravity waves on the tropopause temperature, height and water
           vapor in Tibet from COSMIC GPS Radio Occultation observations
    • Abstract: Publication date: Available online 8 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Attaullah Khan, Shuanggen Jin, Hakan S. Kutoglu
      The tropopause plays an important role in climate change, particularly in Tibet with complex topography and climate change system. In this paper, the temperature and height of the Cold Point Tropopause (CPT) in Tibet are obtained and investigated from COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) GPS Radio Occultation (RO) during June 2006- Feb 2014, which are compared with Lapse Rate Tropopause (LRT) from Atmospheric Infrared Sounder (AIRS/NASA). Furthermore, the impact of Gravity waves (GW) potential energy (Ep) on the CPT-Temperature, CPT-Height, and the variation of stratospheric water vapor with GW Ep variations are presented. Generally the coldest CPT temperature is in June-July-August (JJA) with −76.5°C, resulting less water vapor into the stratosphere above the cold points. The temperature of the cold point increases up to −69°C during the winter over the Tibetan Plateau (25°–40°N, 70°–100°E) that leads to increase in water vapor above the cold points (10 hPa). Mean vertical fluctuations of temperature are calculated as well as the mean gravity wave potential energy Ep for each month from June 2006 to Feb 2014. Monthly Ep is calculated at 5×5° grids between 17km to 24km in altitude for the Tibetan Plateau. The Ep raises from 1.83J/Kg to 3.4J/Kg from summer to winter with mean Ep of 2.5J/Kg for the year. The results show that the gravity waves affect the CPT temperature and water vapor concentration in the stratosphere. Water vapor, CPT temperature and gravity wave (Ep) have good correlation with each other above the cold points, and water vapor increases with increasing Ep.


      PubDate: 2015-12-10T17:16:37Z
       
  • HIRDLS observations of global gravity wave absolute momentum fluxes: A
           wavelet based approach
    • Abstract: Publication date: Available online 9 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Sherine Rachel John, Karanam Kishore Kumar
      Using wavelet technique for detection of height varying vertical and horizontal wavelengths of gravity waves, the absolute values of gravity wave momentum fluxes are estimated from High Resolution Dynamics Limb Sounder (HIRDLS) temperature measurements. Two years of temperature measurements (2005 December to 2007 November) from HIRDLS onboard EOS-Aura satellite over the globe are used for this purpose. The least square fitting method is employed to extract the 0–6 zonal wavenumber planetary wave amplitudes, which are removed from the instantaneous temperature profiles to extract gravity wave fields. The vertical and horizontal wavelengths of the prominent waves are computed using wavelet and cross correlation techniques respectively. The absolute momentum fluxes are then estimated using prominent gravity wave perturbations and their vertical and horizontal wavelengths. The momentum fluxes obtained from HIRDLS are compared with the fluxes obtained from ground based Rayleigh LIDAR observations over a low latitude station, Gadanki (13.50 N, 79.20 E) and are found to be in good agreement. After validation, the absolute gravity wave momentum fluxes over the entire globe are estimated. It is found that the winter hemisphere has the maximum momentum flux magnitudes over the high latitudes with a secondary maximum over the summer hemispheric low-latitudes. The significance of the present study lies in introducing the wavelet technique for estimating the height varying vertical and horizontal wavelengths of gravity waves and validating space based momentum flux estimations using ground based lidar observations.


      PubDate: 2015-12-10T17:16:37Z
       
  • Derivation of gravity wave potential energy density from NDMC measurements
    • Abstract: Publication date: Available online 10 December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Sabine Wüst, Verena Wendt, Carsten Schmidt, Sabrina Lichtenstern, Michael Bittner, Jeng-Hwa Yee, Martin G. Mlynczak, James M. Russell
      Within the Network for the Detection of Mesospheric Change, NDMC (http://wdc.dlr.de/ndmc), we currently operate twelve infrared spectrometers, which are nearly identical in set-up and data processing. These spectrometers are called GRIPS 5 to GRIPS 16 (GRound based Infrared P-branch Spectrometer) and allow the acquisition of rotational temperatures in the mesopause region making use of the OH⁎-airglow phenomenon. We present an algorithm for the estimation of potential energy density using measurements of five GRIPS instruments from 2011 to 2014 at three stations in central and one in Northern Europe. Nightly temperature variations are retrieved for periods shorter and longer than ca. 60 minutes applying an iterative approach of sliding means. Based on these results, monthly mean potential energy density is estimated for the short and the long periods. The Brunt-Väisälä frequency, which is necessary for its calculation, is taken from TIMED-SABER and CIRA-86 data. In order to justify the combination of TIMED-SABER and GRIPS data sets, temperature time series at the different stations are compared. Depending on the periods, an annual and/or semi-annual variation of potential energy density can be observed in most cases which agree quite well with other publications addressing the mesopause at mid-latitudes but relying on different techniques. The influence of the vertical extension of the OH⁎-layer and of the size of the field-of-view on the results is discussed. Finally, we show for the first time that GRIPS measurements, which take place at the same station but which are characterized through differing sizes of the fields of view, can provide additional information about the dominating horizontal wavelengths at mesopause heights.


      PubDate: 2015-12-10T17:16:37Z
       
  • THEMIS observations and riometry: A data comparison with a view to proxy
           and prediction
    • Abstract: Publication date: January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 137
      Author(s): M.J. Birch, J.K. Hargreaves
      A comparison has been made between radio absorption events observed by riometer at selected times of day and bursts of electrons observed in the midnight sector by THEMIS satellites. The correlation is found to be good for absorption in the noon and midnight sectors but poor around dawn and dusk. For noon and midnight the absorption can be estimated from the THEMIS electron flux to better than a factor of 2 in most cases. In the noon sector the absorption follows the THEMIS event by about 30min on average (though with considerable variation from case to case), but by night the absorption precedes the electron flux by about 8min on average. Thus, the flux at THEMIS can be predicted from the absorption in the night sector, the accuracy being better than a factor of 3 in most cases. The flux observed also depends on the location of the satellite, reducing with increasing distance down the tail. It is estimated that the source of the tail events observed in this study was at about 6R e , and comparisons are made with the established general pattern of the substorm in auroral absorption.


      PubDate: 2015-12-05T16:51:17Z
       
  • Sunspots and ENSO relationship using Markov method
    • Abstract: Publication date: January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 137
      Author(s): Danish Hassan, Asif Iqbal, Syed Ahmad Hassan, Shaheen Abbas, Muhammad Rashid Kamal Ansari
      The various techniques have been used to confer the existence of significant relations between the number of Sunspots and different terrestrial climate parameters such as rainfall, temperature, dewdrops, aerosol and ENSO etc. Improved understanding and modelling of Sunspots variations can explore the information about the related variables. This study uses a Markov chain method to find the relations between monthly Sunspots and ENSO data of two epochs (1996–2009 and 1950–2014). Corresponding transition matrices of both data sets appear similar and it is qualitatively evaluated by high values of 2-dimensional correlation found between transition matrices of ENSO and Sunspots. The associated transition diagrams show that each state communicates with the others. Presence of stronger self-communication (between same states) confirms periodic behaviour among the states. Moreover, closeness found in the expected number of visits from one state to the other show the existence of a possible relation between Sunspots and ENSO data. Moreover, perfect validation of dependency and stationary tests endorses the applicability of the Markov chain analyses on Sunspots and ENSO data. This shows that a significant relation between Sunspots and ENSO data exists. Improved understanding and modelling of Sunspots variations can help to explore the information about the related variables. This study can be useful to explore the influence of ENSO related local climatic variability.


      PubDate: 2015-12-05T16:51:17Z
       
  • Mathematical links between optimum solar collector tilts in isotropic sky
           for intercepting maximum solar irradiance
    • Abstract: Publication date: Available online 28 November 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Dorin stanciu, Camelia stanciu, Ioana paraschiv
      The paper presents a mathematical modeling of the optimum tilt for solar collectors for intercepting maximum solar irradiance (power density), at different geographical locations, periods of time and different base-ground types. The solar irradiance received by the collector is estimated based on isotropic sky analysis models, namely Hottel & Woertz model and Liu & Jordan model. The optimum value for the tilt is considered for maximum hourly and respectively daily noon incident solar irradiance. This paper emphasizes the mathematical link between the optima computed under the two considered models assumptions. Also the ground reflectance factor influence on the optimum tilt difference between considered models is presented related to latitude.


      PubDate: 2015-12-01T13:01:30Z
       
  • Comparison of horizontal winds and turbulent eddy dissipation rates
           obtained by two different multi-receiver techniques – Spaced Antenna
           and Postset Beam Steering
    • Abstract: Publication date: January 2016
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 137
      Author(s): Shridhar Kumar, T. Narayana Rao, V.K. Anandan, V.N. Sureshbabu, T. Arunamani
      The horizontal winds and eddy dissipation rates (ε) obtained by two multi-receiver techniques, Spaced Antenna (SA) and Postset Beam Steering (PBS), are compared and contrasted, using Middle and Upper atmospheric radar measurements. Comparison of mean horizontal winds obtained by both methods indicates a good agreement in zonal and meridional winds. On the other hand, the agreement in ε derived by SA and PBS is good in the lower troposphere (below ~9km), but the profiles of ε show some discrepancy in the upper troposphere. While the discrepancy is relatively more in layers of depleted turbulence, it is small in layers of enhanced turbulence. Comparison of signal-to-noise ratio and turbulence variations reveal that these variations are not due to specular echoes, rather due to anisotropic turbulence. The study suggests that these techniques and correction formulae for spectral width work well in the regions of enhanced turbulence but yield relatively less accurate values in regions of depleted turbulence.


      PubDate: 2015-12-01T13:01:30Z
       
  • IFC-Ed. board
    • Abstract: Publication date: December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 136, Part B




      PubDate: 2015-12-01T13:01:30Z
       
  • IFC-Ed. board
    • Abstract: Publication date: December 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics, Volume 136, Part A




      PubDate: 2015-12-01T13:01:30Z
       
  • Validation of water vapor retrieval from Moderate Resolution Imaging
           Spectro-radiometer (MODIS) in near infrared channels using GPS data over
           IAO-Hanle, in the trans-Himalayan region
    • Abstract: Publication date: Available online 27 November 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Shantikumar S. Ningombam, Sridevi Jade, T.S. Shrungeshwara, H.-J. Song
      Integrated precipitable water vapor (PWV) retrieved from Moderate Resolution Imaging Spectro-radiometer (MODIS) in near-infrared channels is examined with the PWV estimated from the Global Positioning System (GPS) data and measured surface temperature and pressure values over Hanle, located at a high-altitude (∼4500m) trans-Himalayan region. Since the accuracy of MODIS derived PWV over the large elevated topography of the region is not well studied, the present work focus on the validation of MODIS PWV using the GPS data during 2005–2012. The study reveals that MODIS PWV compares well with the GPS PWV data with bias −0.018cm, root mean square error (RMSE) 0.137cm and coefficient of determination (R 2) 0.91. The two types of data products are compared on short (daily) and long temporal (monthly-seasonal) scales in order to evaluate the seasonal dependence of PWV. The peak values of PWV from MODIS and GPS data at the site varied from 1.7 to 2.05cm and 1.2 to 1.4cm as the daily and the monthly means, respectively which occurred during August. However, the seasonal peak of PWV occurred during summer as 0.88 and 0.97cm for MODIS and GPS data, respectively. The present study noticed that about 85% of the total PWV estimated from MODIS as well as GPS data lies below 1.0cm over the site. The seasonal study of PWV reveals that MODIS data is found to be underestimating the PWV when compared to GPS data with bias −0.095cm and RMSE 0.215cm particularly during summer. This is due to dry and high-altitude terrain of Hanle particularly during summer months. However, there are marginal differences (bias varied from 0.007 to 0.017cm) during the remaining seasons and seasonally R 2 varies from 0.62 to 0.87. GPS PWV exhibits distinct diurnal cycle with minimum in morning as well as in night and peak in the late afternoon (16–18hrs) irrespective of the seasons. However, the diurnal cycle is very prominent during summer than the rest of the seasons.


      PubDate: 2015-12-01T13:01:30Z
       
  • Annual Minimum Temperature Variations in Early 21st Century in Punjab,
           Pakistan
    • Abstract: Publication date: Available online 30 October 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Misbah Jahangir, Syeda Maria Ali, Bushra Khalid
      Climate change is a key emerging threat to the global environment. It imposes long lasting impacts both at regional and national level. In the recent era, global warming and extreme temperatures have drawn great interest to the scientific community. As in a past century considerable increase in global surface temperatures have been observed and predictions revealed that it will continue in the future. In this regard, current study mainly focused on analysis of regional climatic change (annual minimum temperature trends and its correlation with land surface temperatures in the early 21st century in Punjab) for a period of 1979–2013. The projected model data European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) has been used for eight Tehsils of Punjab i.e., annual minimum temperatures and annual seasonal temperatures. Trend analysis of annual minimum and annual seasonal temperature in (Khushab, Noorpur, Sargodha, Bhalwal, Sahiwal, Shahpur, Sillanwali and Chinoit) tehsils of Punjab was carried out by Regression analysis and Mann-Kendall test. Landsat 5 Thematic Mapper (TM) data was used in comparison with Model data for the month of May from the years 2000, 2009 and 2010. Results showed that no significant trends were observed in annual minimum temperature. A significant change was observed in Noorpur, Bhalwal, Shahpur, Sillanwali, Sahiwal, Chinoit and Sargodha tehsils during spring season, which indicated that this particular season was a transient period of time.


      PubDate: 2015-11-23T13:00:31Z
       
  • On the dependence on solar cycle of the amplitude modulation
           characterizing the mid-latitude sporadic E layer diurnal periodicity
    • Abstract: Publication date: Available online 17 November 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): M. Pezzopane, A. Pignalberi, M. Pietrella
      Spectral analyses are employed to investigate how the diurnal periodicity of the critical frequency of the sporadic E (Es) layer varies with solar activity. The study is based on ionograms recorded at the ionospheric station of Rome (41.8°N, 12.5°E), Italy, from 1976 to 2009, a period of time covering three solar cycles. It was confirmed that the diurnal periodicity is always affected by an amplitude modulation with periods of several days, which is the proof that Es layers are affected indirectly by planetary waves through their nonlinear interaction with atmospheric tides at lower altitudes. The most striking features coming out from this study is however that this amplitude modulation is greater for high solar activity than for low solar activity.


      PubDate: 2015-11-23T13:00:31Z
       
  • Elevated aerosols and role of circulation parameters in aerosol vertical
           distribution
    • Abstract: Publication date: Available online 18 November 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): S.S. Prijith, Marina Aloysius, Mannil Mohan, P.V.N. Rao
      The study examines aerosol loading in different vertical layers of the atmosphere and explores the role of atmospheric circulation parameters in vertical distribution of aerosols and in its seasonal variability. Aerosol vertical distribution over the globe is examined, using long term satellite observations, by considering aerosol loading in different layers of atmosphere upto ∼6km altitudes from surface and fractional contribution of each of these layers to total columnar aerosol loading. Aerosols are observed residing close to the surface in most of the oceanic environments, except over certain regions which are in the close proximity of continents where upper level winds are conducive for long range aerosol transport. In contrast, considerable vertical spread in aerosol distribution with strong seasonal variability, minimum occurring in winter months and maximum in summer, is observed over the continental regions. Vertical spread in aerosol distribution is observed highest over north eastern and north western parts of Africa during northern hemispheric summer, when the convection activity peaks over these regions due to large solar insolation and associated surface heating. Seasonal variation of aerosol vertical spread over both of these regions is observed in phase with variation in atmospheric convergence and vorticity. During summer months, when the aerosol vertical spread is highest, strong surface level convergence and associated cyclonic vorticity is observed along with an upper level (700 to 600hPa) divergence. The surface level convergence and upper level divergence together induce an upward flow of air which carries aerosols from ground to higher altitudes. This mechanism of aerosol vertical transport is further corroborated through the correlation and regression relations of surface convergence/vorticity with aerosol loading above different elevations and hence the study reveals role of circulation parameters in aerosol vertical distribution.


      PubDate: 2015-11-23T13:00:31Z
       
  • Producing K indices by the interactive method based on the traditional
           hand-scaling methodology – preliminary results
    • Abstract: Publication date: Available online 17 November 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): Fridrich Valach, Magdaléna Váczyová, Miloš Revallo
      This paper reports on an interactive computer method for producing K indices. The method is based on the traditional hand-scaling methodology that had been practised at Hurbanovo Geomagnetic Observatory till the end of 1997. Here, the performance of the method was tested on the data of the Kakioka Magnetic Observatory. We have found that in some ranges of the K-index values our method might be a beneficial supplement to the computer-based methods approved and endorsed by IAGA. This result was achieved for both very low (K=0) and high ( K ≥ 5 ) levels of the geomagnetic activity. The method incorporated an interactive procedure of selecting quiet days by a human operator (observer). This introduces a certain amount of subjectivity, similarly as the traditional hand-scaling method.


      PubDate: 2015-11-23T13:00:31Z
       
  • Characteristics of Total Electron Content (TEC) observed from a chain of
           stations near the northern crest of the Equatorial Ionization Anomaly
           (EIA) along 88.5°E meridian in India
    • Abstract: Publication date: Available online 19 November 2015
      Source:Journal of Atmospheric and Solar-Terrestrial Physics
      Author(s): K.S. Paul, A. Das, S. Ray, A. Paul
      The equatorial ionosphere presents some of the highest TEC values in the world coupled with observations of periodic structures. Total Electron Content (TEC) and scintillation data were analyzed from a chain of stations Calcutta (22.58°N, 88.38°E geographic; 32°N magnetic dip), Baharampore (24.09°N, 88.25°E geographic; 35°N magnetic dip) and Farakka (24.79°N, 87.89°E geographic; 36.04°N magnetic dip) situated almost same meridian (88.5°E) during September 2011 and March-April 2012 for elevation greater than 20° so that the ionosphere can be tracked from the 15.50°N south of Calcutta to 31.80°N north of Farakka. Periodic variation of TEC was noticed before TEC bite out, predominantly within a particular latitudinal swath (19°N ‒26°N) along 88.5°E meridian. No periodic structures were observed over the magnetic equator during the observation period on ionosonde records from the magnetic equator station Trivandrum and COSMIC, GRACE and C/NOFS electron density measurements. The present paper reports, perhaps for the first time from the Indian longitude sector, confinement of such periodic structures in TEC primarily within a latitude swath of 19.00°N to 26.00°N almost along the same longitude of 88.5°E.


      PubDate: 2015-11-23T13:00:31Z
       
 
 
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