Atmospheric tides play a critical role in the dynamics and coupling of mesosphere and lower-thermosphere (MLT). Global Circulation Models (GCMs) that aim to span the lower, middle and upper atmosphere must therefore be capable of reproducing the tides and observations of tides are thus crucial to constrain the models. Here we present the first climatology of the 12- and 24-h tides measured at heights

The adiabatic and non-adiabatic behavior of relativistic electrons in the outer radiation belt during the 1 June 2013 geomagnetic storm is studied using data from the Van Allen Probes and THEMIS missions. Analysis of the evolution of the plasma pressure shows that the pressure increased by one order of magnitude during the storm reaching a maximum value towards the end or slightly after the main phase

An analysis on the longitudinal structures in the martian upper atmospheric CO2 densities during the 33rd Martian year (earth year: 2015–2017) is reported herein. The CO2 densities in the altitude region of 165–220 km corresponding to the in-bound periapsis orbits of MAVEN NGIMS during different martian seasons have been considered for this study. The data used spans over a longitude region of −180°

The paper implemented a “standard” coupling system in the South China Sea without any further development avoiding to add a new parameterization on ocean-atmosphere-wave interaction. The sea and the waves influenced tropical cyclone (TC) through the interaction between the air and sea fluxes. The performance of the fully coupled atmosphere-ocean-wave model is overall better that of the uncoupled model

The dissipation of acoustic-gravity waves in the thermosphere due to molecular viscosity and thermal conductivity based on a modified system of hydrodynamic equations is studied. A modification of the system of equations consists in additional taking into account in the linearized Navier–Stokes equations and heat transfer additional terms describing the transfer of momentum and energy due to the background

An attempt has been made to understand the effect of the cirrus clouds on the tropical tropopause thermal structure over a tropical station Gadanki (13.45oN, 79.2oE) using regular radiosonde observation at 12:00Z and CALIPSO measurements at the closest proximity to Gadanki during 2006–2013. As the CALIPSO and radiosonde observation timings are not simultaneous, we considered only those cases when cirrus

Recent studies have shown that day-to-day variability in thermospheric winds (100–300 km altitude) driven by meteorological variability from below affects ionospheric E and lower F regions, highlighting the need for accurate, continuous specification of day-to-day variability throughout the entire atmosphere for geospace weather prediction systems. To better understand the nature of forcing from below

In this paper, we described the basic features and observations bases of the scenario for the substorm expansion phase that we have developed from our research over the past ~10 years. Onset occurs along magnetic field lines of the inner proton plasma sheet, and is first seen in the aurora as beading along the onset aurora arc, which lies near the equatorward boundary of the auroral oval. Growth of

ENSO has significant impact on the precipitation pattern in summer over China. To differentiate the different impacts from El Niño and La Nina, two groups of experiments were conducted using WRF-Chem CO tracer model, with one group for summer 2015 and the other group for summer 2010. The study explained the difference between 2015 and 2010 as strong El Niño and La Nina, respectively, with a perspective

The effect of precipitating high-energy particles on atmospheric physics and chemistry is extensively studied over the last decade. In majority of the existing models, the precipitating particles induced ionization plays an essential role. For such effects, it is necessary to possess enhanced increase in ion production, specifically during the winter period. In this study, we focus on highly penetrating

In this paper, the wavelet packet transform (WPT) is applied to analyze the time-frequency features of three kinds of lightning events (the cloud pulse, the return stroke and the stepped leader) and a new identification method based on WPT is proposed. The magnetic-field data used in this paper were recorded by Nanjing Lightning Location Network in 2018. Firstly, the wavelet spectra of three typical

Surface observations on trace gases such as ozone (O3), oxides of nitrogen (August 2014–May 2017) and carbon monoxide (January 2016–May 2017) were used to investigate O3 chemistry. Study shows O3 concentration is high during winter with a mean value of 35.54 ± 7.16 ppbv and low concentration in monsoon with a mean value of 12.70 ± 3.55 ppbv. Oxides of nitrogen (NOx = NO + NO2) concentrations are high

Preliminary results from the measurement of potential gradient (PG) for the period of March 2018–February 2019 at the University of Kashmir, Srinagar, (34° 03′ N, 74° 51’ E, 1585 m amsl) India is reported. The annual mean diurnal variation of PG represents typical double-maxima pattern with the primary maximum at 0900–1000 LT and the secondary maximum at 1900–2000 LT which is in accordance with the

Information on the state of the ionosphere is of great importance for organizing communications in the short-wave range. One of the main methods for estimating the ionosphere parameters is the use of modeling. Most existing ionosphere models rely on the algorithms presented in the recommendations of the Radiocommunication Sector of the International Telecommunications Union. This work shows one of

This work studies the temporal variation of rain heights in the Sub-Sahelian and Coastal regions of Nigeria using six (6) years Tropical Rain Measuring Mission Precipitation Radar (TRMM-PR) reprocessed data retrieved from the Global Precipitation Measurement (GPM) constellation Satellites and Era-Interim Field of the European Centre for Medium-Range Weather Forecast (ECMWF). The research reveals seasonal

Ionospheric irregularities are small-scale disturbances in the ionosphere which disrupt radio waves by causing amplitude and phase scintillations. Global Navigation Satellite System (GNSS) network can work as two-dimensional array to provide the spatial structure of the irregularities. With derived vertical total electron content (VTEC), we propose a spatial fluctuation of TEC (SFT) parameter to identify

A local maximum value of ionospheric total electron content (TEC) in midlatitude regions, named midlatitude ionospheric peak in this study, has been frequently observed during both the daytime and nighttime. We have carried out a modeling study of midlatitude ionospheric peaks in TEC using the Thermosphere Ionosphere Electrodynamic General Circulation Model (TIEGCM) to investigate possible mechanisms

The secular variation spatial pattern of geomagnetic cutoff rigidity, Rc, is analyzed considering analytical expressions. Störmer analytic Rc equation in terms of geomagnetic latitude is used considering a pure dipolar field for the centered and eccentric dipole coordinates, together with a dipole-quadrupole superposition simplified equation. Linear Rc time trend for the period 1900–2020 in a 5 ° × 15 °

Comparison of the numerical simulation results with experimental data obtained aboard the CHAMP spacecraft has shown that in the eastern longitudes during the local winter period the parameters of electron temperature (Te) enhancement zone in the subauroral ionosphere undergo significant changes depending on the universal time (UT control) as a result of the formation of the shadow region, almost devoid

The importance of gravity waves (GWs) in the redistribution of energy and momentum in the Earth's atmosphere is well known. It is extremely important to understand the nature of variation in the GW characteristics to address issues of coupling in the Earth's atmosphere. We have used digisonde measurements to investigate the variation in thermospheric wave dynamics in the daytime over low-latitudes

We study the dynamics of radiation belt electrons during a 10-day quiet period perturbed by substorm activity and preceding a high-speed stream (HSS), aiming at a global description of the radiation belts in L-shell, L in [2, 6], and energy [0.1, 10] MeV. We combine Van Allen Probes observations and Fokker-Planck numerical simulations of pitch-angle diffusion. The Fokker-Planck model uses event-driven

We have analyzed ULF magnetic field emissions data obtained from identical 3- component search coil magnetometers installed at Indian stations of Agra (Geograph. lat. 27.2°N, long. 78°E), Shillong (25.92oN, 91.88oE), and Kachchh (23.78oN, 71oE) for the months of April 2012 and September 2013 in which three major earthquakes occurred, one of magnitude M = 8.5 in Indonesian region and two of magnitudes

Long-term forecasting of solar activity, over a scale of centuries, is of interest in modeling climate. Reconstructions of solar irradiance based on radionuclides span 9.4 to 11.5 millennia. There is evidence of multiple maxima and minima, as well as changes in trend. Analysis of the data yields ambiguous results. Fourier spectra find long cycles in the data, but these are not confirmed in the time

Ground-based electric field measurements during fair weather and thunderstorms are key parameters for Global Electric Circuit investigations and climate change assessment. We study the variations of near surface electric field during fair weather and thunderstorms. In this work we present daily, monthly and yearly distribution of thunderstorm activity from 2012 to 2019 at different research stations

This paper deals with the observations of stratospheric ozone intruding into the troposphere over the Bharati (69.41° S, 76.19° E) station in Antarctica, made during 35th Indian Scientific Expeditions to Antarctica (ISEA-35) during jet stream conditions. High-resolution multiplatform measurements from radiosonde coupled with ozonesonde, Very High-Frequency (VHF) radar and Micro-Limb Sounder (MLS) and

This work addresses the vertical atmosphere –ionosphere coupling through two cyclonic events AILA (23–26 May 2009) and ‘WARD’ (10–16 December 2009) observed over the North Indian Ocean. Combined ground Digisonde Tirunelveli (8.7oN, 77.8oE) observation, ECMWF reanalysis, and NOAA Outgoing Longwave Radiation data used to reveal the connection between atmosphere –ionosphere system. At the time of tropical

The results of an investigation into whether or not eclipse shadow bands have an atmospheric origin are presented. Using high altitude balloon and ground-based photodiode arrays during the August 21, 2017 total solar eclipse, data revealing the light patterns before and after totality were collected at 600 Hz. These data were then analyzed using spectrograms, which provide information on intensity

Aerosols and cloud interaction remains highly important in the climatic process and its validation with space-based Ozone Monitoring Instrument (OMI) and ground-based observation of Aeronet Robotic Network (AERONET) is therefore essential. OMI and AERONET AODs was logrithmically subset and variations observed in both instruments show spatio-temporal quality of being more noticeable, which could lead

The Annular Solar Eclipse (ASE) occurred on December 26, 2019, which was visible at most of the South Indian subcontinents with greater than 80% obscurity, particularly during the morning hours, and it played a crucial role in the atmospheric dynamics. For the first time, the ground-based measurements have used to investigate the fluctuations of air temperature, relative humidity, atmospheric pressure

In this study, the solar cycle modulation of the connection between boreal winter El Niño-South Oscillation (ENSO) and following summer South Asia High (SAH) are revealed. For El Niño accompanied by low solar cycle (EL & LS) or La Niña accompanied by low solar cycle (LA & LS), the boreal winter ENSO prominently affects the following summer's SAH variation. The SAH is enhanced (weakened) and expanded

Thermodynamic indices have been used as a tool for nowcasting thunderstorms for decades. The present study deals with understanding the variations in threshold values of various thermodynamic indices during pre-monsoon season at two north-eastern Indian stations: Agartala and Guwahati. The study utilises thirty years (1987–2016) of radiosonde data, surface information about thunderstorms, and TRMM

Although the horizontal density structures of the polar ionosphere have been extensively studied mostly using the F-region peak density or total electron content, there are relatively few studies on the vertical density structures. In this review, we present the climatology of the polar ionospheric density not only in the F-region but also in the E-region and topside ionosphere, in comparison with

This study is concerned with the effects of a decrease in the air pollution concentration on the lightning characteristics of two large Brazilian cities. The decrease in air pollution happened from March 20, till April 02, 2020, and it was caused by the social distancing effort to contain the COVID-19 spread in the cities. In São Paulo, the ratio between cloud-to-ground to intracloud flashes and the

Available manually scaled foF2 observations over 50 years on Juliusruh, 33 years on Slough, and 37 years on Rome stations were used to check the association between quiet-time foF2 disturbances (Q-disturbances) and following on isolated magnetic storms. Of course, such cases exist, however Pearson's contingency coefficient, Chi-square and Odds ratio tests applied to check a measure of association gave

This paper presents the ground truth datasets of negative cloud-to-ground (NCG) flashes with one single stroke in five isolated small thunderstorms. By developing a machine-learning method based on the convolutional neural network, we identify the return strokes during the whole life of thunderstorms with the wideband electric field waveform of lightning discharges detected by Jianghuai Area Sferic

The knowledge of the periodic diurnal anisotropy in the cosmic ray (CR) flux intensity as well as the enhanced anisotropy that might accompany Forbush events is not novel. Theoretical models and several methodological approaches such as Fourier techniques developed to predict the diurnal vectors started appearing in the literature since 1960s’. Consequently, the vectors have been successfully calculated

Apparent ionospheric reflection heights estimated using electric field waveforms of negative and positive cloud-to-ground lightning return strokes (-CGs and +CGs) that occurred during the same thunderstorms have been compared. We analyzed electric field waveforms of 101 -CGs and 74 +CGs that were recorded in August 2016 in Florida. For daytime conditions, the mean ionospheric reflection height for

Ionospheric scintillation is quite a common phenomenon over the low latitude regions and in East Africa it is often monitored using measurements from the SCIntillation Network Decision Aid (SCINDA) receivers. The SCINDA receivers over East Africa are characterized by long base lines and data paucity thus offering a huge challenge in the long term scintillation characterization over the region. To alleviate

We present a brief review of observational results contributing to modern ideas on the evolution of stellar activity. Basic laws, derived for both rotation–age and activity–rotation relationships, allow us to trace how the activity of low-mass stars changes with age during their stay on the main sequence. We focus on the evaluation of the activity properties of stars that could be analogs of the young

The present study investigates long-term variation in aerosol optical properties (AOP) and their associated climatic implications over selected cities of Chitral, Gwadar, Karachi, Lahore, Peshawar and Quetta in Pakistan for the period 2005–2018. For this purpose, aerosol optical depth (AOD) and aerosol index (AI) are retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring

We perform a superposed epoch analysis on two groups of selected geospace disturbance events, emerging from single and isolated interplanetary drivers, and resulting in either the enhancement or the depletion of the average relativistic electron Phase Space Density (PSD). We investigate the occurrence of behavioural/temporal patterns of solar wind and geomagnetic parameters, chorus and ULF Pc5 wave

The present study investigates the annual displacement of ITCZ and its role in forming and strengthening the precipitation systems in the southern part of Iran. To this end, the daily precipitation data of 71 meteorological stations were received. Then, the precipitation systems throughout cold seasons (October to May) were extracted. Next, the systems with maximum precipitation average were selected

Time difference of arrival (TDOA) technique is one of many bases to determine lightning strike location employed in a lightning locating system (LLS). In this technique, at least four measurement sensors are required to correctly locate a lightning strike. Usage of fewer number of sensors will result in non-unique solutions to the generated hyperbolas, and hence wrong lightning strike point. This research

Prior to its discovery, O+ from the Earth's high-latitude ionosphere was not expected to be present in any significant amount in the magnetosphere. It is now known that O+ can dominate ionospheric outflow and dominate magnetotail composition during geomagnetically active times. Observations from the Magnetospheric Multiscale (MMS) mission are used here to illustrate properties of O+ in the dayside

A model of electric discharges at mesospheric altitudes has been developed to explain the nature of optical flashes/transient atmospheric events (TAEs) observed aboard the Russian microsatellites “Universitetsky-Tatyana-1”, “Universitetsky-Tatyana-2” and “Vernov”. The model is based on assumption that large-scale areas with a low space charge density and a low electric breakdown threshold can occur

Contemporaneous multi-instrument ground-based optical and meteor radar observations of OH and O2 airglow, temperature and neutral winds during the winter season of November 2018–February 2019 have been used to investigate the dynamics of the mesosphere/lower thermosphere (MLT) (80–100 km) region in the high Arctic at Svalbard, Norway (78°N, 16°E) and at Eureka, Canada (80°N, 274°E). Temperature observations

The impact of initial conditions in predicting lightning activity using the Weather Research and Forecasting (WRF) with the electrification (ELEC) extra package, known as WRF-ELEC model, has been investigated. The severity, frequency, and some physical and dynamical properties of lightning occurred during 11 years (2004–2014) are considered. Four thundercloud events with distinctive characteristics

An observation of altitude descents in high-frequency enhanced ion line (HFIL) and plasma line (HFPL) are examined, and an alternative explanation are presented. The HFIL and HFPL altitudes should be governed by the dispersion relations of ion acoustic and Langmuir waves respectively, and those altitude descents in HFIL and HFPL may be in consequence of the significantly enhanced electron temperature

The present paper reports the results derived from PM2.5 and PM10 concentrations during October 2016–May 2018 using MICROTOPS-II Sunphotometer and high volume samplers at Varanasi. Observed data were categorized and analyzed in order to understand the nature, source of origin and variability with seasons. Observations showed aerosol mass loading during the post-monsoon 2016 and winter 2017 as compared

Using a numerical model of the ELF radio wave scattering by seismogenic localized non-uniformity, we evaluate the earthquake (EQ) magnitude by using modifications in the power spectra of global electromagnetic (Schumann) resonance. The ionosphere non-uniformity is introduced as a disturbance in the vertical profile of atmosphere conductivity above the earthquake. Three types are considered of disturbance:

The observations of vertical total electron content (VTEC) and L1 and L2 band ionospheric scintillations at an equatorial station, Tarawa (Geomag. Coordinates, 2.68°S, 114.26°W), Kiribati, under a complex severe space weather event of 4–9 September 2017, are presented. The VTEC increased significantly by 1.03 and 1.31 TEC units under M5.5 class flare at 20:28 UT on 04 September and M4.2 flare at 01:03

Trends derived from the Leibniz-Institute Middle Atmosphere Model (LIMA) and the MIMAS ice particle model (Mesospheric Ice Microphysics And tranSport model) are presented for a period of 138 years (1871–2008) and for middle, high and arctic latitudes, namely 58 °N, 69 N∘N, and 78 °N, respectively. We focus on the analysis of mesospheric ice layers (NLC, noctilucent clouds) in the main summer season

The problem of air quality in Warsaw is related with the emission of pollutants from combustion of coal or natural gas in winter and it is a different situation than in other capitals in EU, where transportation is the main source of pollution to the air. In Warsaw, the impact of traffic emission on air quality is clearly visible in the warm season of the year. Therefore, it is important to analyse

Daily harmonics of the ionosphere’s total electron content (TEC) can be mapped using Global Navigation Satellite Systems (GNSS), as recently accomplished by Lean and colleagues. Here those harmonics are determined (over oceans only) by tidal analysis of ionospheric path delay from dual-frequency radar altimetry. Data from TOPEX, Jason-1, and Jason-2 altimeters are used, with focus on periods of medium

In this paper, a 20-year (1991–2010) simulation of dust aerosol emission is conducted by using the global climate model CAM 5.1 (Community Atmosphere Model, version 5.1). The simulation results revealed that North Africa, the Arabian Peninsula and the Middle East, East Asia, Australia, and the other regions respectively account for 60%, 18%, 12%, 2.5% and 7.5% of the global dust aerosol emission. On

In this paper an attempt has been made to investigate the impact of different microphysical (MP) parameterization schemes in simulation of leading convective line with trailing stratiform (TS) squall lines observed over the Gangetic West Bengal (GWB) region of India during the pre-monsoon season of March–May using Advanced Research Weather Research and Forecasting (WRF-ARW). The model is employed to

This paper examines some data mining techniques for lightning prediction. If we indicate by one the lightning event occurrence and by zero the non-occurrence of the event, then we will have a binary classification problem. In some cases, the dataset of lightning event is class imbalance. Thus, in the current research, the method of undersampling will be employed to generate several balanced datasets