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

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

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

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

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

A first sounding rocket campaign dedicated to investigate the creation mechanism of Polar Mesosphere Winter Echoes (PMWE) was conducted in April 2018 from the north Norwegian Andøya Space Center (69 ∘N, 16 ∘E). Two instrumented sounding rockets were launched on 13th and 18th of April under PMWE and non-PMWE conditions, respectively. In this paper we give an overview of the PMWE sounding rocket mission

This study employed Machine Learning (ML) technique known as Convolutional Autoencoder to build Statistical Downscaling Model (SDM) emulator. Eight General Circulation Models (GCMs) rainfall datasets were selected under the Representative Concentration Pathway (RCP4.5) emission scenario over Northern Africa. Historical rainfall simulation for the period 1951–2005 from 8 GCMs were applied to train/validate

The bow shock and the dayside magnetopause are the principle boundaries that determine the interaction of the magnetosphere with the solar wind. Specifically, the bow shock determines the properties of the shocked solar wind plasma that interacts with the magnetosphere. In addition to the shocked solar wind plasma, a number of transient events associated with the bow shock and foreshock regions can

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

Noctilucent Clouds (NLC) and Mesospheric Summer Echoes (MSE) are ice-related phenomena that occur occasionally in the mid-latitude summer mesopause region and more frequently in the polar regions. We observe both phenomena above our site at Kühlungsborn (Germany, 54.1°N, 11.8°E) by lidar and radar since 1997 and 1998, respectively. The NLC season 2019 turned out to be record-breaking with respect to

Simultaneous measurements of rocket-borne and ground-based instruments in a common volume were performed from Andøya, Norway (69° N, 16° E) in frame of the recent PMWE-project, devoted to clarify the formation mechanism behind polar mesosphere winter echoes (PMWE). This article focuses on measurements of April, 13th 2018. Despite low solar activity, we observe several radar echoes, giving the launch

The scale height in the plasmasphere (HP) is an important factor to present the dynamic nature and variations of the plasmasphere. It is challenging to build reliable plasmaspheric scale height model because of poor coverage and limited continuity of plasmaspheric sounder data. In this paper, an empirical orthogonal function (EOF) analysis method is applied to organize the HP obtained from total electron

Zenith Wet Delay (ZWD) represents an important parameter in the Global Navigation Satellite Systems (GNSS) positioning, meteorology, and weather forecasting as it assembled to the Integrated Water Vapour (IWV) that is important for weather prediction. It is difficult to be predicted due to its temporal and spatial resolution. With the increasing development in machine learning, Artificial Neural Network

The SYM-H and AE geomagnetic indices can be considered as proxies of the response of the Earth’s magnetosphere and ionosphere to solar magnetic activity. They indirectly monitor some electric current systems which flow in the ionosphere and magnetosphere whose dynamics are directly or indirectly related to the Sun–Earth interaction. Consequently, their temporal changes reflect processes occurring in

A correlation study is performed to investigate possible connections between the stratospheric gravity waves and the ionospheric plasma bubble induced GPS signal scintillations. Using the COSMIC 1 neutral temperature data (10–30 km), we extract gravity wave amplitudes with vertical wavelengths from 2.5 to 10 km within the latitudinal range from 37.5S to 37.5N. We then calculated the occurrence of high

The auroral oval is a well-established concept, introduced more than five decades ago. The Alfvénic oval, on the other hand, is a very recent concept, which has been revealed in both observational and numerical studies. This is the first review of the global Alfvénic oval, while also defining primary, secondary and tertiary layers of the Alfvénic oval. The focus lies on the large-scale dynamic properties

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

The Central and Eastern European Infrasound Network (CEEIN) detects significant irregularities in microbarom arrivals between 15 and October 18, 2017. The processes driving the irregular microbarom arrivals are searched in the microbarom source region in the North Atlantic and in the stratospheric waveguide. Generation of microbaroms is simulated using ocean WAVEWATCHIII wave-action model and an updated

In this paper, we study the interaction between a nighttime Medium Scale Traveling Ionospheric Disturbance (MSTID) and geomagnetic north-south oriented field-aligned plasma depletion structure over Hanle, Leh Ladakh (32.7°N, 78.9°E; Mlat. ~24.1°N), India on a geomagnetically quiet night (06 May 2019, Ap = 4). The results are based on the observations carried out using a newly established airglow imager

Estimation of cloud-cleared radiances, without utilizing any supplementary sensors for INSAT-3D Sounder InfraRed window observations is presented here. This method utilizes simulated clear sky radiances by radiative transfer for TOVS (RTTOV) tool, with the help of global numerical weather prediction (NWP) models analysis and forecast fields, unlike the previously reported approaches where observations

Near field acoustical signals from fireballs (ranges < 200 km), when detected by dense ground networks, may be used to estimate the orientation of the trajectory of a fireball (Pujol et al., 2005) as well as fragmentation locations (Kalenda et al., 2014; Edwards and Hildebrand, 2004). Distinguishing ballistic arrivals (from the cylindrical shock of the fireball) from fragmentation generated signals

On August 11, 2012, two successive strong earthquakes (Mw = 6.4 and 6.3) hit the East Azerbaijan Province, NW Iran at 12:23 and 12:34 UTC. This study investigated the variations of multi earthquakes precursors, (Land Surface Temperature (LST), Total Electron Content (TEC), Outgoing Longwave Radiation (OLR), and Air Temperature (AT) of non-seismic phenomena before and after the successive Ahar (Iran)

Simultaneous measurements of ambient atmospheric black carbon (BC) mass concentrations and radiative fluxes were carried out over Satopanth glacier in the central Himalayas from September 22 to October 2, 2016, as a part of a glacier campaign experiment. The daily mean atmospheric BC concentrations varied between 165 ± 20–263 ± 32 ng m−3 with a mean of 199 ± 54 ng m−3 during the observational period

Vertical wavenumber spectra of gravity wave (GW) perturbations of horizontal wind, temperature and ascent rate of the balloon obtained from 10 years (2007–2017) of high resolution radiosonde measurements in the troposphere and lower stratosphere over a tropical station, Gadanki (13.450 N,79.20 E) are investigated. The vertical wavenumber spectrum of ascent rate perturbations obtained from radiosonde

Since 1999 radar continuous observations of polar mesospheric echoes have been conducted on the Norwegian island of Andøya (69.30°N, 16.04°E), with the ALWIN radar (1999–2008) and MAARSY (since 2011). Traditionally these observations have been named after their seasonal occurrence, i.e., Polar Mesosphere Summer Echoes (PMSE) and Polar Mesosphere Winter Echoes (PMWE). PMSE are much stronger than PMWE

We investigate the formation of He+ and O+ multiple-nose structures observed by the Helium, Oxygen, Proton, and Electron instrument onboard Van Allen Probes A on December 2, 2012. Previous studies have suggested that multiple-nose structures can be formed by changes in the convection electric field. However, the specifics of how these changes can produce multiple-nose structures have been left unresolved

Using data from GNSS networks spanning the European-African sector, the occurrence of ionospheric irregularities induced during the geomagnetic storm of 6–8 March 2016 was studied. During the main phase of the event, strong and unusual mid latitude irregularities were detected at 50°-60°N on the night of March 6, 2016 before midnight and in the early hours of March 7, 2016. At the low latitudes, intense

The atmospheric surface layer turbulence statistics and surface fluxes during the winter season over Anantapur, a semi-arid region, are investigated using sonic anemometers mounted 10 m and 18 m above ground level on a 32-m meteorological tower. This paper aims to investigate the applicability of Monin–Obukhov similarity theory and to understand the influence of wind speed on the turbulence intensities

Due to the growing real-time data of a global navigation satellite system (GNSS) applications and strict requirements for positioning users, especially under the condition of abnormal ionospheric activity, the fast and high-accuracy model is increasingly becoming important. In the past few years, the spherical harmonic (SH) model is one of the commonly-used methods, which has been widely used for global

Solar UV-A radiation causes photocarcinogenesis and skin photoageing, but it could also benefit cardiovascular health and protection from autoimmunity. In this study, a method for the near real-time monitoring of UV-A solar radiation dose based on Earth Observation satellites imagery is proposed. The calculated satellite-derived radiant dose has been compared to ground measurements provided by Public

There are several reports about thermal anomalies associated with the impending earthquakes (EQs); among which the underlying mechanism is linked with the main shock with long, intermediate and short-term precursors. In this paper, we analyzed thermal anomalies from Moderate Resolution Imaging Spectroradiometer (MODIS) based Land Surface Temperature (LST) of three different magnitudes and shallow depth

We report a unique simultaneous occurrence of two plasma structures using a 630.0 nm all-sky airglow imager in Hanle, India. The characteristics indicate that the observed structures are Medium Scale Travelling Ionospheric Disturbances (MSTIDs) of different types, namely periodic and single dark band. Based on previous understandings of Perkins instability, we explore the role of polarization electric

A long-term statistical analysis of thermospheric tides in an altitude range from 150 to 400 km is presented. The analysis is based on a dataset with 31 multi-day experiments conducted from an incoherent scatter radar at Arecibo Observatory between 1984 and 2015. This is the first time that the climatological mean and seasonal variations of the thermospheric tides and their response to solar activities

Ground-based microwave radiometer (MWR) is with ability to measure liquid water path (LWP) and cloud base height (CBH) with the aid of infrared thermometer (IRT) under all skies. Using the 6-year MWR observations at Wuhan (WH), Xianning (XN) and Jingzhou (JZ) in central China, variations of cloud occurrence frequency (COF) and LWP as well as vertical structure of COF for non-precipitating clouds are

The understanding of the excitation mechanism of the sodium D-line nightglow emission is important for many investigations of atomic sodium in the upper mesosphere region. In 1939, Sidney Chapman proposed a first scheme of the chemical reactions involving sodium and ozone to explain the yellow sodium line doublet in the terrestrial nightglow. Later, it became clear that this mechanism could not explain

An attempt is made to connect the moisture present above the boundary layer and its association with the cloud development and boundary layer turbulence using Large Eddy Simulation (LES) and aircraft observations. The dry boundary layer (BL) with shallow clouds observed during Cloud-Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) over the arid Indian peninsula is investigated

Hybrid simulations, where ions are treated kinetically and electrons as a fluid, seek to describe ion microphysics with maximum physical fidelity. The hybrid approach addresses the fundamental need for space plasma models to incorporate physics beyond magnetohydrodynamics. Global hybrid simulations must account for a wide range of both kinetic ion and whistler/Alfvén wave spatio-temporal scales in

We apply a numerical differentiation method for gradients of bending angle (BA) vertical profiles to determine the atmospheric boundary layer (ABL) height. The basic idea to obtain profiles of BA vertical gradient is to minimize an objective functional, with the Tikhonov regularization term being the second order derivative of the function to be determined; the regularization parameter is chosen as

Seasonal variability in the vertical distribution of ozone over a tropical station, Thumba (8.5°N, 76.9°E) is investigated using nine-years (2011–2019) of ECC ozonesonde data obtained as part of Tropical Tropopause Dynamics (TTD) campaigns. Ozone exhibits a clear annual variation in the lower troposphere (0–2 km) with winter maximum (49.2 ± 3.6 ppbv) and summer monsoon minimum (21.9 ± 0.7 ppbv). In

Trends in meteorological variables have become clear. However, temporal variations and climate oscillations are less clear, especially for extreme events. This study investigates temporal variations in extreme daily precipitation, extreme daily maximum and minimum temperature (Tmax and Tmin) during the last decades in Shaanxi Province, China, by a quantile perturbation method with a nonparametric bootstrap

The scalar forward propagation equation, most often with the parabolic approximation, has been used extensively for simulating ionospheric radio propagation. More recently, the formalism has been applied at HF frequencies where external magnetic field effects must be accommodated. This paper presents a generalization of the forward propagation equation to accommodate vector fields with forward-marching