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

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

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

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

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

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

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

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

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

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

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

Gravity waves play an important role in the propagation of energy and momentum from the lower atmospheric regions into the upper atmosphere. Depending on the varying dissipation conditions, these waves generated in the lower atmosphere can propagate higher into the atmosphere. As the neutrals and plasma share the same volume in the upper atmosphere, these waves affect both these densities as they propagate

The possibility of sporadic E (Es) layer formation in the mid-latitude nighttime lower thermosphere by horizontal homogeneous and inhomogeneous (vertically changing) winds is investigated by analytical and numerical solutions of continuity equation for dominant heavy metallic ions Fe+. The study firstly showed that when ions maximal vertical convergence rate exceeds the diffusive displacement of their

Most of the heavy rainfall comes from the severe convective storms. Convective scale numerical weather prediction with grid-lengths of a few km or less, is capable for a more successful representation of convective scale processes and explicitly representing different types of convective storms. However, despite these high-non-hydrostatic models, in some specific atmospheric cases associated with very

Data of temperature anomalies from different sites worldwide for the last millennium are used to extract long-term components in global, northern and southern hemisphere temperatures for their quantitative contribution to climate change to evaluate and to search for possible causes. The Method of Global Minimum which is capable of making a self-consistent selection of trends from a data set and singling

Stable auroral red (SAR) arcs are the consequence of interaction of the outer plasmasphere (plasmapause) with energetic ions of the ring current. In this work the event of SAR arc observation using the all-sky imager (ASI) at the Yakutsk meridian (130°E; 200°E, geom.) simultaneously with the registration of plasmapause and energetic ion fluxes aboard the Van Allen Probe B satellite at the beginning

Ionospheric disturbance (ID) detected using GPS based Total Electron Content (TEC) measurements are widely used to study the morphology and dynamics of the ionosphere, and its impact on radio communication and satellite based navigation. The IDs normally derived as rate of change of TEC (ROT) between consecutive ionospheric pierce points at uniform time interval implicitly results in non-uniform spatial

The refined Cloud Imaging and Particle-Size (CIPS) cloud wind tracking algorithm is elaborated and the wind product is assessed against the Navy Operational Global Atmospheric Prediction System - Advanced Level Physics and High Altitude (NOGAPS-ALPHA) winds and the horizontal wind model (HWM14) climatological winds. Multiple searching frame sizes are adopted to generate the preliminary wind sets which

Solar flares are large explosions in the sun’s atmosphere. They can damage satellites and overload electrical systems. To manage that risk, finding methods of efficiently predicting future events is very important. In this paper we introduce a full-Sun flare prediction method based on the Hidden Markov modelling with two hidden states. We concentrate on the soft X-ray emission data near the minimum

The present work reports atmospheric opacity at 220 GHz over Indian Astronomical Observatory (IAO)-Hanle during 2006 to 2018. The opacity data were derived from the radiometric measurement of sky-brightness temperature as a function of zenith angle for every 10 min during day and night. Since the operating frequency range is not completely opaque during rainfall or cloudy atmosphere, observations are

Solar flare forecasting is limited by the current understanding of mechanisms that govern magnetic reconnection, the main physical phenomenon associated with these events. As a result, forecasting relies mainly on climatological correlations to historical events rather than the underlying physics principles. Solar physics models place the neutral point of the reconnection event in the solar corona

The response of the atmosphere to solar irradiance and geomagnetic activity is analyzed in experiments with the Whole Atmosphere Community Climate Model (WACCM) under idealized forcings. Four experiments are carried out combining high (H) and low (L) solar radiative forcing with high (7) and low (3) geomagnetic activity: H7 (with high radiative forcing and high geomagnetic activity), H3, (high/low)

The results of modeling and analysis of ionospheric parameters during disturbed geomagnetic field are presented. Hourly and 15-min data of the ionospheric critical frequency (foF2) at Paratunka site (Kamchatka, Russia, 53.0 N and 158.7 E) for the period 1968–2019 were applied. The modeling was based on ionospheric parameter multicomponent model developed by the authors. In order to refine model parameters

The “Nose-like” ion spectral structures are characterized by the deep inward penetration of ions from the near-Earth plasma sheet and can extend to low L shells in the inner magnetosphere. The stationary “Nose-like” ion structures are believed to be driven by the stationary electric and magnetic field during quiet geomagnetic times. However, the global distribution picture, especially for each MLT

The wave forcing from below allows the neutral atmosphere to drive short-term variability in the ionosphere. Recent modeling studies have shown that secondary waves originated from the nonlinear interaction of the atmospheric tides with planetary scale waves can contribute significantly to day-to-day variability of the ionosphere. In this study we used MLT neutral wind measured at São João do Cariri

High-precision precipitable water vapor (PWV) can be obtained using the global navigation satellite system (GNSS). However, the spatial resolution of the GNSS-derived PWV is insufficient, particularly for areas without sufficient GNSS stations. Although other techniques, such as radiosonde sounding, can also be used to obtain PWV, generating PWV images with high precision and high spatial resolution

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

Energetic particle precipitation is one of the main processes by which the sun influences atmospheric composition and structure. The polar middle atmosphere is chemically disturbed by the precipitation-induced production of nitric oxides (NOx) and hydrogen oxides (HOx) and the associated ozone (O3) loss, but the importance for the dynamics is still debated. The role of precipitating medium energy electrons

The paper deals with the dynamics of the young Sun, physical conditions in the early Solar System and on the Earth. An extended interpretation of the faint young Sun paradox and its possible solutions are proposed. Various hypotheses are discussed including their advantages and disadvantages. The faint young Sun paradox follows from the Standard Solar Model with the conservation of mass condition.

For the aim of surface refractivity analysis, the overall territory of Quebec has been divided in a desired number of areas from North to South using clustering analysis. The meteorological data used in the analysis are collected from 50 stations located in various climatic regions over Quebec for the year 2013. It is found that the best input data for the identification of areas is the water vapour

We use the example of two Stealth-type coronal mass ejections (stealth CMEs) registered by LASCO C2 on the quiescent Sun on 16 June 2010 and in the active region NOAA 11520 7 July 2012 to demonstrate that these mass ejections emerged in a lower-coronal area where an intense short-term radiation burst was registered in several extreme ultraviolet channels. It is established for the first time that the

Numerical high-resolution modeling of nonlinear acoustic-gravity waves (AGWs) generated at the Earth's surface and propagating to the thermosphere shows that wave characteristics are depending on modifications in the mean density, temperature, molecular dissipation and composition due to variations of solar activity (SA). Amplitudes of temperature wave perturbations are generally larger at high SA

Results of analysis of the proxy of Coronal Hole (CH) Power index, Pch, combined with the high speed streams HSS of solar wind for a period from 2011 to 2019 are presented. It is found that the long-term variation of Pch index shows a trend of growing Pch towards the minimum of solar cycle while most of other identities of solar activity tend to diminish. Superposition of fast solar wind of CH origin

Noctilucent clouds (NLC) are mesospheric ice clouds occurring in the summer hemisphere at high latitudes and an altitude of about 83km. This region is the coldest of the earth’s atmosphere and is characterized by the presence of wave interaction and dissipation. The processes involved here lead to a variety of structures and instabilities that become visible in noctilucent clouds and are observed by

The magnetotail dipolarization during substorms is a mesoscale dynamical phenomenon, well documented by in-situ spacecraft observations, numerical simulations, and ground-based optical measurements. The magnetic energy release during substorms results in significant plasma heating and the formation of strong temperature and density gradients behind the dipolarization front. Such gradients are the source

Based on discussions held at a workshop in Bra-Pollenzo, Italy, this paper elaborates upon 19 outstanding questions of plasma physics in the Earth's magnetosphere. The questions are grouped according to (a) driving processes, (b) radiation belt and ring current issues, (c) auroral physics, (d) internal plasma processes, and (e) magnetosphere-ionosphere mapping issues. Future needs for magnetospheric

Thunderstorms and lightnings are natural particle accelerator systems. Terrestrial gamma-ray flashes, caused by relativistic runaway electron avalanches, produce bursts of X and γ rays, energetic enough to produce photo-nuclear reactions within the atmosphere. Such reactions cause the generation of new isotopes, which modify the air composition locally and produce new ways of detecting and characterizing

Sixteen variables describing the state of the magnetosphere are examined in the years 1991–2007; the sixteen variables include nine geomagnetic indices plus seven measures of electron and ion precipitation into the atmosphere, the rate of substorm occurrence, the pressure and number density of the ion plasma sheet, the flux of substorm-injected electrons, and the radiation-belt electron flux. Eight

This study analysed NCEP/NCAR reanalysis datasets of wind speed components at multiple pressure levels from 1956 to 2015 with a view to examining seasonal variations in wind shears in relation to convective precipitation over West Africa. It also estimated the West African Monsoon (WAM) wind shear index and related it to the WAM dynamics during different seasons (December to February: DJF; March to

This study aims to assess Urban Heat Island (UHI) as Surface Urban Heat Island (SUHI) of Karachi which ensures the existence of UHI effect on sustainability, based on the analysis of rapid urbanization and Land Use Land Cover (LULC) changes on the average temperature warming in Karachi. Satellite images are employed to extract statistics regarding land-use in Karachi city and to obtain land surface

Water vapor tomography technique is a research point in global navigation satellite system (GNSS) meteorology. However, GNSS tomography technique has an inherent issue of design matrix sparsity, which leads to the ill-posed problem in the inversion of normal equation. Singular value decomposition (SVD) method is commonly used to resolve this problem but performs poorly due to the large fluctuation

Energetic charged particle precipitation associated with solar wind perturbations causes enhanced high-frequency radiowave absorption in the high-latitude ionosphere. This study models 38.2 MHz cosmic noise absorption (CNA) by utilising measurements from the Imaging Riometer for Ionospheric Studies (IRIS) at Kilpisjärvi, Finland obtained during solar cycle 23 (1996–2009) associated with the passage

Present paper studies the γ-ray spectrum observed using NaI (Tl) scintillation detector over a year. The paper reports the presence of a distinct diurnal pattern in the total number of γ-ray counts detected by the NaI detector. The counts start decreasing after sunrise and show gradual recovery after sunset. The amplitude of this variation is quite significant ( >10%) at the observation site Tirunelveli

Cloud base height (CBH), and equivalent potential temperature (θe) at 850 hPa are able to distinguish convective events day. The present work is analysing CBH and θe as ingredients for the formulation of a new thermodynamic index over a tropical station Kolkata during pre-monsoon season of 2016–2019. We have performed skill score analysis to evaluate the performance of new index. The result shows that

Lightning is one of the most important extreme weather conditions and is associated with heavy convective rain and thunderstorms. However, the present understanding of such systems as well their effect on precipitation characteristics are insufficient for proper modelling. In this paper, the rain microphysics is studied at Kolkata using an optical disdrometer in relation to the lightning activities

The design and laboratory demonstration of a prototype sensor for measuring thermospheric red-line winds from a 6U CubeSat is described. The sensor uses the flight spare interferometer developed for the MIGHTI instrument on NASA's ICON satellite with a more limited scientific scope to enable it to fit within the limited volume of a 6U CubeSat. A performance model coupled with laboratory phase shift

GPS troposphere tomography is one of the most powerful techniques used to extract 3D model of the water vapor and wet refractivity using the observations from local and regional GPS networks. In this technique each unknown parameter is related to the one 3D elements called voxels. This approach is a mixed-determined inverse problem because propagated signals do not pass through some of the voxels.

This paper presents the results of radio observations of ionospheric disturbances associated with the fall of a meteoroid (unique in its initial energy of 173 kt TNT equivalent) off the east coast of the Kamchatka Peninsula on 18 December 2018. The ionospheric disturbances were measured with the multipath radio system designed for oblique sounding and located at the Harbin Engineering University campus

The signature of the low-latitude mesosphere response to the February 2017 minor sudden stratosphere warming (SSW) was detected using the observations of a meteor radar at Fuke (19.5°N, 109.1°E) a low-latitude station in China and ERA-5 data. Radar detected the zonal wind reversal in the mesosphere three days before the SSW event, whereas the ERA-5 does not reproduce the mesospheric wind response at

The paper presents climatology of the mean winds and diurnal and semidiurnal tides observed by meteor radars at high latitudinal stations Svalbard (78°N, 16°E) and Tromsø (70°N, 19°E) based on 18 years (2001–2018) and 16 years (2003–2018) of measurements, respectively. The main focus of the study is to clarify the features of the diurnal tide (DT) because it is poorly known particularly at high latitudes

The interannual variability of the total ozone (TOZ) in the equatorial region (5°S – 5°N) has been studied using the satellite daily and monthly data in 1978–2018. The coupling of the equatorial TOZ changes to the quasi-biennial oscillation (QBO) of the zonal wind in the equatorial stratosphere has long been known. However, the detailed analysis of the daily deseasonalized TOZ data over the course