We address deviations in the source bearing of natural pulsed extremely low frequency (ELF) radio signals (Q-bursts) in the Schumann resonance band. The model of smooth day – night non-uniformity is used. The observer is located at the Ukrainian Antarctic station “Akademik Vernadsky” (65.25° S and 64.25° W), and the source is positioned at the same meridian at latitudes of 20° S; 25° N, or 85° N. The

A comparative study of precipitation microphysics along with the possible causative mechanisms for the inter-seasonal variation of raindrop size distribution over Thiruvananthapuram and Kolkata – the two tropical stations of Indian sub-continent has been highlighted in this paper. In addition to the contrasting geographical and climatic variations, the importance of the two locations lies in the fact

The nonlinear theory of acoustic-gravity waves (AGWs) in the atmosphere is revisited with the effects of the Coriolis force. Previous theory in the literature (Mendonça and Stenflo, 2015) is advanced. Starting from a set of fluid equations modified by the Coriolis force, a general linear dispersion relation is derived which manifests the coupling of the high-frequency acoustic-gravity waves (AGWs)

There is still no complete understanding of the optical radiation of ball lightning. So far no explanation has been found for the variety of its colors, the reasons for the change of color, the generation of light flashes etc. This may be due to incomplete data on the nature of the time dependence of its intensity of its radiation. The analysis of a video film shot in July 2016 near Blagoveshchensk

Duct climatology over the South China Sea (SCS) was statistically analyzed in the present study based on 10-year ECMWF reanalysis data. The results show that the spatial distributions of the ducting events over the SCS exhibit obvious monthly variation. May is a key time point that separates the spatial distribution pattern of duct characteristics over the SCS. Ducting events often occur in the first

The modernized GLONASS (GLObal NAvigation Satellite System) provides new opportunities for estimating ZWD (zenith wet delay) and PWV (precipitable water vapor) for meteorology and climate related studies. In this study, ZWD/PWV retrieval from GLONASS and GPS (Global Positioning System) observations are assessed by comparing the results with radiosonde observations from nearly co-located GNSS (Global

The cloud droplet size distribution (CDSD) and microphysical properties prior to monsoon rain events is studied using in-situ ground observations over a high altitude site in Western Ghats, India. The cloud microphysical properties, such as cloud droplet number concentration (CDNC), liquid water content (LWC), cloud droplet spectrum, droplet effective diameter (ED), droplet mean radius (Rm), spectral

The exceptionally solar and geomagnetic quiet winter of 2019–2020 provides a very useful scenario to study polar mesospheric radar echoes. Such a condition limits the impact of ionisation caused by geomagnetic storms and particle precipitation and allows to investigate the role of moderate electron densities as well as neutral dynamics in formation and transport of the structures causing these echoes

The study explores the spatial variability and related characteristics of south Asian summer monsoon rainfall and extreme rainfall events based on APHRODITE rainfall products. An attempt was also made to investigate their association with global climate indices. Most of the South Asian regions are vulnerable to extreme rainfall events and many of these lead to major hydrological disasters. Such events

The influence of phase and amplitude of Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO) on the interannual variability of the Indian summer monsoon rainfall (ISMR) over North East India (NEI) has been studied first time from 1960 to 2015. The independent contribution of different phases and amplitude of IOD and ENSO in the interannual variabilities of ISMR over NEI is explained by

Moderate ionospheric disturbances combined with storm signatures are characterized by the positive ionospheric index (WU), the negative index (WL), and the range (WE = WU – WL). We assign weights to these indices as a function of the magnitude of the W-index, the observation latitude of the critical frequency of the F2 layer, foF2 (the F2 layer peak electron density, NmF2) or total electron content

We study variations in the rigidity spectrum and anisotropy of cosmic rays (CRs) by using the data from satellite and ground-based observations within the worldwide network of cosmic-ray detectors through the global spectrographic survey. The studied period covers 28 and 29 October and 2 November 2003 (GLE65, GLE66, and GLE67). We determined CR differential rigidity spectra at individual hours of the

A mathematical model is constructed of the equatorial electrojets flowing in the ionosphere which are generated by thunderstorms occurring at low latitudes. We use the narrow definition of the global electric circuit (GEC) that includes only atmospheric and ionospheric electric fields and currents generated by thunderstorms, and ignores the contributions of all ionospheric and magnetospheric generators

Modeling the neutral density in the upper atmosphere is a major challenge as it involves a comprehensive understanding of the complex coupling between the thermosphere and its environment. In addition, this system is strongly driven by solar activity, which is hardly predictable. This complexity limits the ability of thermospheric models to accurately estimate thermospheric characteristics, such as

The paper proposes a methodology and presents the results of modeling fluctuations of transionospheric radio signals propagating under conditions of intermittent ionospheric turbulence. To account for the intermittency of turbulence, the earlier developed model of a non-Gaussian multifractal phase screen is further extended to the case of the log-Poisson cascade model and additionally validated. Employing

The accurate representation of the ionospheric electron density in 3-dimensions is a challenging problem because of the nature of horizontal and vertical structures on both small and large scales. This paper presents the development of a global three-dimensional (3-D) electron density reconstruction based on radio occultation data during 2006–2019 and neural networks. We demonstrate that the developed

The analysis of two rainfall structures of Southwest China Vortex (SCV) during June 14–15, 2008 (event 1) and July 8–9, 2010 (event 2) over eastern Sichuan Basin is presented by using observations from Tropical Rainfall Measuring (TRMM). Through comparisons with statistics of convective and stratiform precipitation, corrected polarization temperature, precipitation particles and latent heat for these

The sky waves generated by lightning are used to study the ionosphere. Previous studies calculated the reflection height of the ionosphere D region based on the time delay between the ground wave and the first skywave. This paper presents a new method for detecting the ionosphere. A set of ground wave delay values are used to calculate the height corresponding to the first and second skywaves. The

Climatological structure of the quasi-2-day wave (Q2DW) at middle latitudes in temperature and horizontal winds in the mesosphere and lower thermosphere (MLT) was compared between the northern and southern hemispheres. Determination of the Q2DW in temperature was based on observation data by the Microwave Limb Sounder (MLS) onboard NASA's Earth Observing System (EOS) Aura satellite over 17 years from

Monthly averages of the superposed values of decay times of meteor echoes from underdense meteor trails obtained by meteor radar observations at Cachoeira Paulista (22.7°S, 45°W), Brazil, have been employed to estimate temperature and to study the diurnal temperature fluctuations in the upper mesosphere and lower thermosphere region. The monthly diurnal amplitudes and phases in meteor radar temperatures

The paper considers the formation of electric fields in the atmosphere at altitudes of 50–70 km after especially powerful tropospheric cloud-to-ground discharges, leading to the initiation of high-altitude discharges. It is known that a necessary condition for initiation of a nighttime sprite is the electric field of uncompensated charge in a cloud of more than 128 Td at an altitude of about 75–80 km

Continuous global monitoring of lightning has been important in recent years to study a possible relationship with global warming. Consequently, several networks to detect lightning have been installed at various spatial scales (regional and global). One of these networks is the World Wide Lightning Location Network (WWLLN), which has been monitoring lightning since 2003. It is also important to monitor

Recently for a number of thunderstorm systems in different regions of the planet there have been reports of observations of high frequency radio emission with duration varying from several to more than one hundred of milliseconds which may both be isolated or precede the lightning initiation. There is a consensus that this radiation originates from continuous sequences of short-duration discharges

Earthquake events are usually associated with atmospheric processes variations. Some of the important events in seismic periods include the atmospheric electricity/conductivity modification, which mostly depends on the ion population in the vicinity of earthquake preparation area. Radon, together with cosmic radiation are the major ionization sources in the lower troposphere. The radon induced soil

The lower ionospheric disturbances associated with the Super Cyclonic Storm Amphan over the Bay of Bengal have been presented in this paper. The disturbances were observed by sub-ionospheric Very Low Frequency (VLF) radio signals from two navigational transmitters VTX and NWC, received at Cooch Behar, India. Strong variations of the nighttime signal amplitudes exceeding three times their standard deviations

The long-term variations in foF2 at Hobart (52.88°S, 147.32°E), Canberra (35.28°S, 149.13° E) and Christchurch (43.53°S, 172.64°E) stations, located in the mid-latitude zone in the Southern Hemisphere were analyzed using 1947–2006 years of the data. The saturation, solar and geomagnetic activity and seasonal effects were removed mainly by using 12-month running mean, linear and multiple regression

Energy and circulation in the Earth's magnetosphere and ionosphere are largely determined by conditions in the solar wind and interplanetary magnetic field. When the driving from the solar wind is turned off (to a minimum), we expect the activity to die down but exactly how this happens is not known. A recent study utilized global MHD simulations to addressed the questions of what constitutes the quietest

In the present study, frequency spectra of the electric field corresponding to the various cloud events, such as, initial breakdown process, regular pulse bursts, chaotic pulse trains and recoil streamers have been analysed. For the purpose, electric field radiated by cloud flashes were obtained simultaneously by a wide bandwidth antenna system and two narrow bandwidth antenna systems tuned at 3 MHz

This paper presents a relationship of lightning activity with maximum air temperature, Bowen ratio, rainfall, cloud ice contents and Aerosol Optical Depth (AOD) over India during transition period from dry to wet seasons. Lightning flash count data and weather parameters are retrieved from the Tropical Rainfall Measuring Mission (Lightning Imaging Sensor - LIS) and the Moderate Resolution Imaging Spectroradiometer

Wind speed is involved in multiple scales physical phenomena and depends on specific features, that are not always easy to simulate numerically. Alternative solution that combines the physical advantages provided by numerical weather prediction (NWP) simulations and statistical models is investigated for wind speed forecast. Several aspects that influence the wind speed forecast error at synoptic stations

The externally imposed vertical drift in the F-region is an extremely important driver of ionospheric dynamics but is very difficult to measure or map. Ionospheric servo algorithms have used hmF2 as F-region observable to infer the vertical drift. However, an even more plentiful observable is the total electron content (TEC) whose coverage over northern mid-latitudes has both spatial and temporal availability

There is increasing interest to understand thermospheric neutral wind and ionized plasma coupling, especially by using empirical observations. This is the first study that reports simultaneous measurements of thermospheric neutral wind and equatorial plasma bubble (EPB) speeds over the African equatorial region. Neutral wind speeds were obtained using a Fabry-Perot interferometer (FPI), while EPB speeds

Time series of mesospheric temperature and pressure altitude are produced through combining observations by the Halogen Occultation Experiment (HALOE), Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER), and Solar Occultation for Ice Experiment (SOFIE) instruments. Time series of both temperature and pressure altitude are produced through the combination of HALOE/SABER providing

A review of the impact of the cold-ion and cold-electron populations in the Earth’s magnetosphere is presented. The cold populations are defined by total energy less than approximately 100 eV, i.e. in the energy range which is strongly affected by spacecraft charging and that often dominates the total plasma density. We also include the warm plasma cloak in the review, since it overlaps partially with

A variety of magnetospheric plasma populations have been proposed to impact solar wind-magnetosphere coupling. These magnetospheric populations could mass load the dayside magnetopause and include the plasmaspheric plume, plasma cloak, ion plasma sheet, and dayside ion outflow. Each has different densities, ion composition, and spatial/temporal occurrences at the dayside magnetopause which may coupling

High frequency (HF) radio wave propagation is sensitive to ionospheric disturbances caused by space weather. Changes in propagation conditions can be directly measured with an HF transmitter/receiver link. This paper presents data from one such link, consisting of a transmitter located in Ottawa, ON, Canada, and a directional receiver located in Alert, NU, Canada. The transmitter emits signals at 6

In this work, we present the uncertainties of the empirical model developed to predict the solar quiet regular daily field variation (Sq) over the Brazilian sector called the Solar Quiet Reference Field (SQRF) model. The SQRF is based on the magnetic station records from the Embrace Magnetometer Network (Embrace MagNet) during the solar cycle 24. Although the prediction and the magnetic field records

Total column precipitable water vapour (PWV) is retrieved using radio occultation retrievals of water vapour from COSMIC satellites over four regions of India. This analysis is carried out to assess the accuracy of the radio occultation technique for estimating PWV and to observe the PWV variation over these regions. The impact points of radio occultation are investigated for one year to select those

Gravity waves play an important role not only in transferring the momentum and energy to the upper atmosphere but also significantly contribute in different global atmospheric phenomenon like Brewer-Dobson circulation along with planetary waves. Larger differences in the gravity wave model parameters with the real observations has recommended more observational studies for better predictions. In this

In this work, the variations in the dynamical complexities in soil temperature variations were compared with that of air temperature using measured temperature parameters from different stations located in Nigeria. These parameters were also compared to the monthly averages of rainfall. The data sets were analysed using nonlinear time series analytical techniques. The results reveal that the annual

The particle size distribution of Polar Mesospheric Clouds (PMC) is closely related to the fundamental processes of cloud formation and evolution. Still, despite substantial observational efforts, specific details about the particle size distribution have remained obscure. In this study, we aim at deriving more constraints on PMC size distributions by combining optical measurements from two satellite

This work analyzed ERA5 (ECMWF ReAnalysis) data from 1979 to 2018 to study changes in stratospheric gravity waves (GWs) associated with stratospheric sudden warming (SSWs). GW variations are examined by separating them into polar vortex split and displacement events. In general, GW amplitudes show enhancements prior to the wind reversal at 10 hPa and 60°N and reductions after the wind reversal. GW

A simple method has been proposed to determine acoustic-gravity wave (AGW) characteristics at lower ionosphere (mesosphere) heights by measuring VLF radio signal amplitudes. For relatively short radio paths (less than ∼ 1500 km long) we obtained the simple relations for estimation of AGW neutral density fluctuation and for vertical displacement of an elementary volume of atmospheric gas. The proposed

Numerical simulations are performed to investigate the radiative and cloud microphysical effects (direct and indirect effects respectively) of the Saharan dust aerosols and the subsequent perturbations of the radiation budget over the tropical East Atlantic Ocean. Simulations are conducted for July 1–31, 2010 over three two-way nested domains covering 0–25°N, 30–60°W using the Weather Research and

An analysis of vertical total electron content (TEC) estimates from the MIT Madrigal database is performed for the regions surrounding the eye of Hurricane Michael (2018). Absolute and detrended TEC values show a noticeable increase during the tropical cyclone (TC) relative to fluctuations at the same locations prior to the storm. Direct comparisons of TEC perturbation magnitudes to the number of lightning

This study theoretically investigates the transport of broadband solar radiation in the Earth's cloudy atmosphere (extended and broken) by considering three plane parallel layers: i) thin bottom layer adjacent to the Earth's surface; ii) intermediate layer where clouds are most embedded; and iii) upper layer that is essentially cloud-free with possible occurrence of only thin clouds. These three layers

This study presents a method of measuring atmospheric turbulence from resonance-fluorescence lidar observations of atmospheric Na layer density fluctuations, which is used to characterize turbulent eddy diffusion (kzzTurb) from 85 km to 105 km altitude over the Andes Lidar Observatory (ALO) in Cerro Pachón, Chile, (30.3°S, 70.7°W) at timescales between 12 seconds and 78 seconds. Na lidar measurements

The three-dimensional ionospheric electron density (Ne) over Japan is retrieved by assimilating the ground-based total electron content (TEC) datasets into the International Reference Ionosphere (IRI) background model. To reduce the computational burdens encountered in the full Kalman filter (KF) algorithm, the simplified KF (SKF), a time-independent data assimilation scheme with no recursion, is adopted

One of the most striking properties of Kinetic Alfvén Waves (KAW) is that, unlike the also Alfvénic Electromagnetic Ion Cyclotron (EMIC) waves, these waves are right-hand polarized in the plasma frame. In particular, this signature property is key for the identification of KAW from in situ measurements of plasma waves. From the theoretical point of view, both the dispersion relation and the polarization

Rainfall is the most important meteorological variable that influences the economic development of Rwanda. Changes in rainfall trends and variability over recent past years have become a great concern to policymakers and scientists. This study aims at examining the spatiotemporal variability of rainfall over Rwanda and the teleconnections of rainfall with different large-scale ocean-atmospheric variables

The magnetospheric physics research community uses a broad array of quantitative data-model comparison methods (metrics) when conducting their research investigations. It is often the case, though, that any particular study will only use one or two metrics, with the two most common being Pearson correlation coefficient and root mean square error (RMSE). Because metrics are designed to test a specific

Since Akasofu introduced the concept of the substorm in 1964, numerous refinements have been added to the phenomenological model of how auroral substorms develop. Here, we review several of the most important of these including; polar cap patches, intensifications of the Polar Activated Band (PAB) at the poleward edge of the bulge, the development of new arcs poleward, the generation of auroral streamers

We report a special polar rain aurora case around 11:24 UT on October 27, 2003, where intense polar rain electrons produced observable polar rain auroral emission with the shape of a roughly dawn-dusk aligned bar. Associated solar wind speed and density observations during the event were around 450 km/s and 2.5 cm−3 respectively. The interplanetary magnetic field (IMF) components Bx, By, and Bz were

A morphological examination of the Kitt Peak photospheric magnetic maps has been made over three sunspot cycles in order to study the morphology of unipolar magnetic regions and sunspots. Unipolar magnetic regions (positive and negative) are a series of weak, large-scale longitudinal bands, extending from 0° to 60° in latitude and alternatively aligned in longitude. The first finding is that unipolar

A statistical study of strong quasi-two-day waves (QTDWs) is carried out from the intensities and rotational temperatures of OH(6–2) and O2b(0–1) emissions measured from the “El Leoncito” Astronomical Complex (31.8°S, 69.3°W) between 2006 and 2020. These emissions correspond to layers centered at 87 km and 95 km altitude, respectively. The period, amplitude and phase of each QTDW are obtained after

We report on a Polar Mesospheric Cloud (PMC) front structure observed on July 2, 2007 over Greenland. This structure appears to be localized solitary wave, with a sharp boundary that separates a cloud and cloud-free region. Near-coincident temperature measurements indicate a 20 K temperature difference between these two regions that likely contributed to the sharp PMC front boundary. Gravity wave (GW)

The Arctic middle atmosphere was affected by major sudden stratospheric warmings (SSW) in February 2018 and January 2019, respectively. In this article, we report for the first time the impact of these two events on the middle atmospheric nitric oxide (NO) abundance. The study is based on measurements obtained during two dedicated observation campaigns, using the Sub-Millimetre Radiometer (SMR) aboard