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

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

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

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 (130ºE; 200ºE, geom.) simultaneously with the registration of plasmapause and energetic ion fluxes aboard the Van Allen Probe B satellite at the beginning

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

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

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 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

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

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

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

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

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.

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 “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

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

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

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

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

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

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

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

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

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

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

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

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

The lack of reliable global E-region electron density or conductivity measurements has hampered a detailed and quantitative understanding of the E-region electrodynamic processes. The characterization of the global E-region ionospheric irregularities as a function of local time, longitude, and season remains a great challenge. In this study, we evaluate the electron densities retrieved by Wu (2018)

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

Prompt creation of new multi-MeV electron and proton radiation belts in the normally benign slot region between inner and outer Van Allen zones was observed by the short-lived Combined Release and Radiation Effects Satellite (CRRES) mission almost 30 years ago. Flux oscillations at lower energies coincident with ULF wave measurements and consistent with drift resonance were also a feature of the CRRES

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

In this paper, GNSS ionospheric observations from ground-based and spaceborne systems were simulated, and the global 3D ionospheric density field was reconstructed by Kalman-Filter algorithm. Various errors and influences in the assimilation of the ionospheric data were analyzed, and corresponding improvement methods were proposed, which were verified from the following two aspects based on simulation

A conspicuous and intermittent signature of a 120-day oscillation is found in the winds and tides in the mesosphere and lower thermosphere (MLT) over a Southern hemispheric equatorial station, São João do Cariri (7.4oS, 36.5oW) for the first time using meteor radar observations during the interval 2004–2008. The intermittent 120-day modulation can be as high as 10 m/s in the MLT winds. However, the

Among the physical processes in the solar wind (SW) plasma, the processes taking place in the vicinity of the front of the interplanetary shock wave and on the front itself are of particular interest. In this paper, we present an analytical description of such processes which is based on the solution of a system of nonlinear equations of magnetohydrodynamics in a thin layer surrounding the front of

A new nowcasting method is herewith proposed to monitor the crucial components of the variability of the stratospheric ozone depletion. A demonstration of this method is performed considering the daily measurements of the minimum air temperature in the latitude range 50oN – 90oN, at 50 hPa, during the period 1/1/1979-06/04/2020. The motivation for choosing this geographical area is the fact that unusual

For detection of rather large ionospheric structures (such as high-latitude ionospheric troughs, main ionospheric trough, etc.) using Global Navigation Satellite Systems (GNSS) we suggest employing the analysis of anomalous deviations in behavior of the absolute slant total electron content (TEC) on particular “GNSS receiver - GNSS satellite” lines of sight (LOSs). Using data of four high-latitude

Daily variations of the Atmospheric Electric Field (AEF) allow to observe separately the atmospheric electricity due to global and local factors. Observations of the AEF are made for three different sites of Pakistan during fair weather conditions. These three sites are Islamabad (ISB), Muzaffarabad (MZF) and Balakot (BKT). Analyses of the diurnal variations of the atmospheric electric field for these

Meteorological processes such as tides influence ionospheric variability through vertical coupling. For the first time, we have used data from Communication Navigation Outage and Forecasting System (C/NOFS) satellite from 2008–2015 to develop a Neural Network (NN) vertical E×B drift model over the African region, with inclusion of a proxy of tides as one of the inputs together with other physical and

The study investigates the gravity waves activity detected in the mesosphere/lower thermosphere (MLT) region (80–120 km) using airglow observations performed by the Spectral Airglow Temperature Imager (SATI) at the Sierra Nevada Observatory (SNO) (37.06∘N, 3.38∘W). In this analysis column emission rates of the OH Meinel (6–2) and O2 Atmospheric (0–1) bands, as well as rotational temperatures derived

This study aims to model diurnal Land Surface Temperature (LST) on a local scale of an arid environment by utilizing the Artificial Neural Network (ANN) and time series analysis of Landsat-8 satellite imageries. An arid region containing an in-situ LST station (DRA) located in Nevada, United States, was chosen as a test site. 78 Landsat-8 satellite imageries covering the test site were utilized to

The ordinary wave critical frequency foEs is measured routinely by ionosondes and used widely in estimating the intensity and occurrence of sporadic E (Es) metal ion layers. Recently, however, it was realized that foEs overestimates Es intensities because it corresponds to the sum of both the layer metal ion plasma and the regular E region plasma densities. To account for this, a new parameter, foμEs

The spatio-temporal dynamic of the substorm on December 24, 2014 in the interval from 16:00 to 17:00 UT was analyzed by data of large observational complex: magnetometers data by the Scandinavian network and by the longitudinal chain of the Russian auroral stations, the auroral dynamics in Apatity and data of THEMIS satellites. During the interval under study the THEMIS-E and THEMIS-D satellites were

Aerosol plays an important role in the climate system by affecting the radiative and energy balances. Hence, in this paper, the spatial patterns of aerosol burden and aerosol optical properties (AOD) in four the Coupled Model Intercomparison Project phase 5 (CMIP5) models over East Asia during 2001–2005 are compared to quantify inter-model differences and to evaluate AOD simulations against observations

We report on a statistical study of prominence eruptions (PEs) using a catalog of these events routinely imaged by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) in the 304 Å pass band. Using an algorithm developed as part of an LWS project, we have detected PEs in 304 Å synoptic images with 2-min cadence since May 2010. A catalog of these PEs is made available

Atmospheric temperature has both variations with time constants of order ½ year or longer, such as trends, annual and semiannual oscillation as well as variations with shorter time constants such as two-day waves, diurnal and semidiurnal tides, and gravity waves. Long-term amplitudes, such as trends and solar flux variations, have been determined from the time series of observed sodium lidar temperatures

This study is focused on investigating how well the day-to-day variability of HF propagation in the bottomside ionosphere can be simulated using a state-of-the-art ionosphere model coupled to a whole atmosphere model driven by the lower atmosphere. The SAMI3 ionosphere model has been coupled to the WACCM-X whole atmosphere model, which was nudged with NAVGEM-HA to incorporate the effects of lower atmospheric

Atmospheric phase screen (APS) is one of the main error sources of interferometric synthetic aperture radar (InSAR) measurements. In order to accurately retrieve displacement fields, it is necessary to use advanced methods to eliminate the tropospheric effect of interferograms. In this paper, the land subsidence in Kurdistan province of Iran is investigated using Sentinel-1A acquisitions on a single

An active mapping mission is described that unambiguously connects measurements in the Earth's magnetosphere to visible aurora in the atmosphere. The core of the mission is an electron-beam source operated on a spacecraft in the equatorial magnetosphere, with the electron beam traveling along the Earth's magnetic-field lines to the atmosphere, depositing its energy to create an optical beam-spot in

Digital difference filters were used for the analysis of data of the spectral observations of the rotational temperature and emission intensity of vibrationally excited hydroxyl (OH*) at altitudes 85–90 km at observatories Zvenigorod (56° N, 37° E) for 2004–2016 years and Tory (52° N, 103° E) for 2012–2017. The monthly-average values and standard deviations of mesoscale perturbations of the OH* emission

Atmospheric tides dominate the mesosphere and lower thermosphere (MLT) dynamics and show seasonal, interannual as well as long term variability. In the present study, MLT wind data obtained between 1999 and 2019 from meteor radar observations at Cachoeira Paulista (22.7∘S, 45.0∘W), Brazil, have been used to investigate similarities and differences in the diurnal, semidiurnal and terdiurnal tide amplitudes

Analytic theory, developed in the companion paper in order to describe the coherence properties of the high frequency wave field propagating through the stochastic transionospheric channel with the inhomogeneous background layer and anisotropic fluctuations of the electron density, is further analyzed extended and specified to obtain the numerical results, which illustrate the fields coherence properties

Rigorous analytic solution is constructed for the first of 2 s-order space position and frequency coherence function (which is alternatively also termed as symmetric) of the high-frequency wave field propagating through the stochastic transionospheric channel with the inhomogeneous layer of the background ionosphere and anisotropic fluctuations of the electron density in the approximation of the appropriate