Abstract. We propose a new method to estimate ion escape from unmagnetized planets that combines observations and models. Assuming that upstream solar wind conditions are known, a computer model of the interaction between the solar wind and the planet is executed for different ionospheric ion production rates. This results in different amounts of mass loading of the solar wind. Then we obtain the ion

Abstract. In this study, we use mutual information to characterise statistical dependencies of seed and relativistic electron fluxes in the Earth's radiation belts on ultra low frequency (ULF) wave power measured on the ground and at geostationary orbit . The benefit of mutual information, in comparison to measures such as the Pearson correlation, lies in the capacity to distinguish nonlinear dependencies

We present a statistical survey of large-amplitude, asymmetric plasma and magnetic field enhancements detected outside the diamagnetic cavity at comet 67P/Churyumov–Gerasimenko from December 2014 to June 2016. Based on the concurrent observations of plasma and magnetic field enhancements, we interpret them to be magnetosonic waves. The aim is to provide a general overview of these waves' properties

Non-specular meteor trail echoes are radar reflections from plasma instabilities that are caused by field-aligned irregularities. Meteor simulations are examined to show that these plasma instabilities, and thus the associated meteor trail echo, strongly depend on the meteoroid properties and the characteristics of the atmosphere in which the meteoroid is embedded. The effects of neutral winds, as

Over the hours of 05:00–09:00 UT on 8 June 2001, the extreme ultraviolet (EUV) instrument on board the IMAGE satellite observed a shoulder-like formation in the morning sector and a post-noon plume-like structure. The plasmapause formation is simulated using the test particle model (TPM), based on a drift motion theory, which reproduces various plasmapause structures and evolution of the shoulder feature

The comparative research of the influence of different types of auroral particle precipitation and polar cap patches (PCPs) on the global positioning system (GPS) signals disturbances in the polar ionosphere was done. For this purpose, we use the GPS scintillation receivers at Ny-Ålesund and Skibotn, operated by the University of Oslo. The presence of the auroral particle precipitation and polar cap

Abstract. We investigate if the presence of meteoric smoke particles (MSP) influences the electron temperature during artfical heating in the D-region. The presence of MSP can result in height regions with reduced electron density, so-called electron bite-outs, due to charging of MSP by electrons. Artificial heating depends on the height variation of electron density. By transferring the energy of

The concept that geospace storms are comprised of synergistically coupled magnetic storms, ionospheric storms, atmospheric storms, and storms in the electric field originating in the magnetosphere, the ionosphere, and the atmosphere (i.e., electrical storms) was validated a few decades ago. Geospace storm studies require the employment of multiple-method approaches to the Sun–interplanetary medium

Simulations of the ionospheric response to solar flux changes driven by the 27 d solar rotation have been performed using the global 3-D Coupled Thermosphere Ionosphere Plasmasphere electrodynamics (CTIPe) physics-based numerical model. Using the F10.7 index as a proxy for solar extreme ultraviolet (EUV) variations in the model, the ionospheric delay at the solar rotation period is well reproduced

In 2003, a decreasing trend was reported in the long-term (1962–2001) fair weather atmospheric electric potential gradient (PG) measured in the Széchenyi István Geophysical Observatory (NCK; 47∘38′ N, 16∘43′ E), Hungary, Central Europe. The origin of this reduction has been the subject of a long-standing debate, due to a group of trees near the measurement site which reached significant height since

Abstract. Using OI6300 airglow images collected over São João do Cariri (7.4° S, 36.5° W) from 2000 to 2007, the equatorial plasma bubble (EPB) zonal drifts were calculated. A strong day-to-day variability was observed in the EPB zonal drifts due to the complexity in the dynamics of the nighttime thermosphere-ionosphere system near the equator. The present work investigated the contribution of the

We investigate the reflection of low-harmonic fast magnetosonic (MS) waves at the local two-ion cutoff frequency (fcutHe+). By comparing the wave signals of the two Van Allen Probes satellites, a distinct boundary where wave energies cannot penetrate inward are found in the time–frequency domain. The boundary is identified as the time series of local fcutHe+. For a certain frequency, there exists a

The nonstationarity of the terrestrial bow shock is analyzed in detail from in situ magnetic field measurements issued from the fluxgate magnetometer (FGM) experiment of the Cluster mission. Attention is focused on statistical analysis of quasi-perpendicular supercritical shock crossings. The present analysis stresses for the first time the importance of a careful and accurate methodology in the data

We present results of noon–midnight meridional plane global hybrid-Vlasov simulations of the magnetotail ion dynamics under a steady southward interplanetary magnetic field using the Vlasiator model. The simulation results show magnetotail reconnection and formation of earthward and tailward fast plasma outflows. The hybrid-Vlasov approach allows us to study ion velocity distribution functions (VDFs)

Abstract. Terrestrial ecliptic dayside observations of the exospheric Lyman-α column intensity between 3–15 Earth radii (Re) by UVIS/HDAC at CASSINI have been analysed to derive the neutral exospheric H-density profile at the Earth's ecliptic dayside in this radial range. The data were measured during CASSINIS's swing by manoeuvre at the Earth on 18 August 1999 and are published by (Werner et al.,

Abstract. We use a newly developed global Hall MHD code to investigate how reconnection drives magnetotail asymmetries in small magnetospheres. Here, we consider a scaled-down, Earth-like magnetosphere where the ion inertial length (δi) is artificially inflated to one planetary radius (the real Earth's δi ≈ 1/15–1/20 RE in the magnetotail). This results in a magnetotail width on the order of 30 δi

Abstract. During auroral substorms the electric currents flowing in the ionosphere change rapidly and a large amount of energy is dissipated in the auroral ionosphere. An important part of the auroral current system are the auroral electrojets whose profiles can be estimated from magnetic field measurements from Low Earth Orbit satellites. In this paper we combine electrojet data derived from the Swarm

The magnetosheath is defined as the plasma region between the bow shock, where the super-magnetosonic solar wind plasma is decelerated and heated, and the outer boundary of the intrinsic planetary magnetic field, the so-called magnetopause. Based on the Soucek–Escoubet magnetosheath flow model at the Earth, we present an analytical magnetosheath plasma flow model around Mercury. The model can be used

Abstract. Seasonal features of geomagnetic activity and their solar wind-interplanetary drivers are studied using more than 5 solar cycles of geomagnetic activity and solar wind observations. This study involves a total of 1239 geomagnetic storms of varying intensity identified using the Dst index from January 1963 to December 2019, a total of 75863 substorms identified from the SML index from January

Abstract. Seasonal and latitude oscillations of equatorial ionization anomaly (EIA) were investigated by zonal mean total electron content (TEC) provided from global gridded GNSS data from 1999 to 2017. Maximum monthly zonal mean TEC values showed NH spring equinox’s value is higher than fall's. Some fluctuations are observed due to upward planetary wave propagation in equinoxes and winter especially

The ionosonde at the Sodankylä Geophysical Observatory (SOD; 67∘ N, 27∘ E; Finland) routinely performs vertical sounding once per minute which enables the study of fast ionospheric variations at a frequency of the long-period geomagnetic pulsations Pc5–6/Pi3 (1–5 mHz). Using the ionosonde data from April 2014–December 2015 and colocated geomagnetic measurements, we have investigated a correspondence

Abstract. Measurements of height dependent electric field (E) and neutral wind (u) are important governing parameters of the Earth's upper atmosphere, which can be used to study e.g., how auroral currents close, or how energy flows between the ionized and neutral constituents. The new EISCAT 3D (E3D) incoherent scatter radar will be able to measure a three-dimensional ion velocity vector (v) at each

We investigate the generation of charge due to collision between projectiles with sizes below ∼1 µm and metal surfaces at speeds ∼0.1 to 10 km s−1. This corresponds to speeds above the elastic limit and well below speeds where volume ionization can occur. Impact charge production at these low to intermediate speeds has traditionally been described by invoking the theory of shock wave ionization. By

This study investigates the use of a vespagram-based approach as a tool for multi-directional comparison between simulated microbarom soundscapes and infrasound data recorded at ground-based array stations. Data recorded at the IS37 station in northern Norway during 2014–2019 have been processed to generate vespagrams (velocity spectral analysis) for five frequency bands between 0.1 and 0.6 Hz. The

The mesosphere and lower thermosphere (MLT) is a critical region that must be accurately reproduced in general circulation models (GCMs) that aim to include the coupling between the lower and middle atmosphere and the thermosphere. An accurate representation of the MLT is thus important for improved climate modelling and the development of a whole atmosphere model. This is because the atmospheric waves

Abstract. The 2020 summer season has revealed frequent occurrences of noctilucent clouds (NLCs) around the Northern hemisphere at middle latitudes (45–55° N), with the lowest latitude at which NLCs were seen being 34.1° N. In order to investigate a reason for this NLC extraordinary summer season, we have analyzed long-term Aura/MLS satellite data for all available summer periods from 2005 to 2020.

We use a full-wave approach to find the field of monochromatic whistler waves, which are excited and propagating in the low nighttime ionosphere. The source current is located in the horizontal plane and can have arbitrary finite distribution over horizontal coordinates. The ground-based horizontal magnetic field and electric field at 125 km are calculated. The character of wave polarization on the

Abstract. In the Institute of Space Techniques and Technologies of the National Center of Space Research and Technology (Almaty, Republic of Kazakhstan) the DIAS (Detection of Ionosphere Anomalies Software) was developed and used for scientific research. The software was designed for ionosphere anomalies detection, identifying and analyzing from satellite spectral and wave data from scientific payload

Abstract. Previous observations have provided a clear indication that the dusk-dawn (v⊥y) sense of both slow (< 200 km s−1) and fast (> 200 km s−1) convective magnetotail flows is strongly governed by the Interplanetary Magnetic Field (IMF) By conditions. The related “untwisting hypothesis” of magnetotail dynamics is commonly invoked to explain this dependence, in terms of a large-scale magnetospheric

Abstract. In magnetospheric missions, burst mode data sampling should be triggered in the presence of processes of scientific or opera- tional interest. We present an unsupervised classification method for magnetospheric regions, that could constitute the first-step of a multi-step method for the automatic identification of magnetospheric processes of interest. Our method is based on Self Organizing

Abstract. Snow cover changes has a direct bearing on the regional and global energy and water cycles, and the change in Earth's climate condition The study of long term altitudinal (spatial and temporal, 2000–2017) in the coverage of snow and glaciers in one of the world’s largest mountainous region, the Hindu Kush Himalayan (HKH) region including Tibet have been studied using remote sensing data from

A sporadic-E (Es) layer is generally associated with a thin-layered structure present in the lower ionosphere, mostly consisting of metallic ions. This metallic ion layer is formed when meteors burn in the upper atmosphere, resulting in the deposition of free metal atoms and ions. Many studies have attributed the presence of the Es layer to the metallic ion layer, specifically when the layer is observed

We report an attenuation of hiss wave intensity in the duskside of the outer plasmasphere in response to enhanced convection and a substorm based on Van Allen Probe observations. Using test particle codes, we simulate the dynamics of energetic electron fluxes based on a realistic magnetospheric electric field model driven by solar wind and subauroral polarization stream. We suggest that the enhanced

As proposed by Saka (2019), plasma injections arising out of the auroral ionosphere (ionospheric injection) are a characteristic process of the polar ionosphere at substorm onset. The ionospheric injection is triggered by westward electric fields transmitted from the convection surge in the magnetosphere at field line dipolarization. Localized westward electric fields result in local accumulation of

The historical magnetic observatory Clementinum operated in Prague from 1839 to 1926. The data from the yearbooks that recorded the observations at Clementinum have recently been digitized and were subsequently converted, in this work, into the physical units of the International System of Units (SI). Introducing a database of geomagnetic data from this historical source is a part of our paper. Some

Ground-based inverse synthetic aperture radar is a tool that can provide insights into the early history and formative processes of planetary bodies in the inner solar system. This information is gathered by measuring the scattering matrix of the target body, providing composite information about the physical structure and chemical makeup of its surface and subsurface down to the penetration depth

The nature of the semi-annual variation in the relativistic electron fluxes in the Earth's outer radiation belt is investigated using Van Allen Probes (MagEIS and REPT) and Geostationary Operational Environmental Satellite Energetic Particle Sensor (GOES/EPS) data during solar cycle 24. We perform wavelet and cross-wavelet analysis in a broad energy and spatial range of electron fluxes and examine

In this work, we simulated the atmospheric drag effect on two model SmallSats (small satellites) in low Earth orbit (LEO) with different ballistic coefficients during 1-month intervals of solar–geomagnetic quiet and perturbed conditions. The goal of this effort was to quantify how solar–geomagnetic activity influences atmospheric drag and perturbs satellite orbits, with particular emphasis on the Bastille

Abstract. This article summarizes the results of an analysis of solar radio bursts detected by the e-Compound Astronomical Low cost Low-frequency Instrument for spectroscopy and Transportable Observatory (e-CALLISTO) spectrometer hosted by the University of Rwanda, College of Education. The data analysed were detected during the first year (2014–2015) of the instrument operation. The Atmospheric Imaging

Abstract. Heavy rainfall events causing floods and flash floods are examined in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere system. The superposed epoch (SPE) analyses of solar wind variables have shown a tendency of severe weather to follow arrivals of high-speed streams from solar coronal holes (Prikryl et al., 2018). Precipitation datasets based on rain-gauge and

Abstract. Recent simulation studies have provided evidence that pulsating aurorae (PsA) associated with high-energy electron precipitation is having a clear local impact on ozone chemistry in the polar middle mesosphere. However, it is not clear if PsA are frequent enough to cause longer-term effects of measurable magnitude. There is also an open question of the relative contribution of PsA-related

The plasma around comet 67P/Churyumov–Gerasimenko showed remarkable variability throughout the entire Rosetta mission. Plasma boundaries such as the diamagnetic cavity, solar wind ion cavity and infant bow shock separate regions with distinct plasma parameters from each other. Here, we focus on a particular feature in the plasma: warm, slow solar wind protons. We investigate this particular proton

Abstract. Out of the two Venus flybys that BepiColombo uses as a gravity assist manoeuvre to finally arrive at Mercury, the first took place on 15 October 2020. After passing the bow shock, the spacecraft travelled along the induced magnetotail, crossing it mainly in the YVSO-direction. In this paper, the BepiColombo Mercury Planetary Orbiter Magnetometer (MPO-MAG) data are discussed, with support

The only published description of the solar wind sector (SS) term used for the reference level in the post-event and real-time derivation of the Polar Cap (PC) indices, PCN (Polar Cap North) and PCS (Polar Cap South), in the version endorsed by the International Association for Geomagnetism and Aeronomy (IAGA) is found in the commented publication, Janzhura and Troshichev: Identification of the IMF

Ensemble simulation of the atmospheric general circulation at altitudes up to the lower thermosphere is performed using the 3-D nonlinear mechanistic numerical model MUAM. The residual mean meridional circulation (RMC), which is the superposition of the mean Eulerian and wave-induced eddy components, is calculated for the boreal winter. Changes in the vertical and meridional RMC velocity components

Abstract. Atmospheric tides play a key role in coupling the lower, middle and upper atmosphere/ionosphere. The tides reach large amplitudes in the Mesosphere and Lower Thermosphere (MLT) where they can have significant fluxes of energy and momentum and so strongly influence the coupling and dynamics. The tides must therefore be accurately represented in Global Circulation Models (GCMs) that seek to

Abstract. The concept of electromotive force appears in various electromagnetic applications in geophysical and astrophysical fluids. An overview of the electromotive force and its applications to the solar wind are discussed such as the electromotive force profile during the shock crossings and the observational tests for the mean-field model against the solar wind data. The electromotive force is

Abstract. During the main phase of geomagnetic storms large positive ionospheric plasma density anomalies arise at middle and polar latitudes. A prominent example is the tongue of ionisation (TOI), which extends poleward from the dayside storm-enhanced density (SED) anomaly, often crossing the polar cap and streaming with the plasma convection flow into the nightside ionosphere. A fragmentation of

The ionospheric total electron content (TEC) provided by the International GNSS Service (IGS) and the TEC simulated by the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics (CTIPe) model have been used to investigate the delayed ionospheric response against solar flux and its trend during the years 2011 to 2013. The analysis of the distinct low-latitude and midlatitude TEC response over

We have derived the behavior of decadal temperature trends over the 24 h of local time, based on zonal averages of SABER data, for the years 2012 to 2014, from 20 to 100 km, within 48∘ of the Equator. Similar results have not been available previously. We find that the temperature trends, based on zonal mean measurements at a fixed local time, can be different from those based on measurements made

Abstract. We investigate the reflection of low-harmonic fast magnetosonic (MS) waves at the local two-ion cutoff frequency (fcutHe+). By comparing the wave signals of the two Van Allen Probes, a distinct boundary where wave energies cannot penetrate inward are found in time-frequency domain. The boundary is identified as the time series of local fcutHe+. For a certain frequency, there exists a spatial

Abstract. Energetic particle precipitation associated with pulsating aurora (PsA) can reach down to lower mesospheric altitude and deplete ozone. It is well documented that pulsating aurora is a common phenomenon during substorm recovery phases. This indicates that using magnetic indices to model the chemistry induced by PsA electrons could underestimate the energy deposition in the atmosphere. Integrating

Mesoscale convective systems (MCSs) are especially visible in the summertime when there is an advection of warm maritime air from the west. Advection of air masses is enriched by water vapour, the source of which can be found over the Mediterranean Sea. In propitious atmospheric conditions, and thus significant convection, atmospheric instability or strong vertical thermal gradient leads to the development

We present a method for augmenting spacecraft measurements of thermospheric composition with quantitative estimates of daytime thermospheric composition below 200 km, inferred from ionospheric data, for which there is a global network of ground-based stations. Measurements of thermospheric composition via ground-based instrumentation are challenging to make, and so details about this important region

Magnetosheath jets are regions of high dynamic pressure, which can traverse from the bow shock towards the magnetopause. Recent modelling efforts, limited to a single jet and a single set of upstream conditions, have provided the first estimations about how the jet parameters behave as a function of position within the magnetosheath. Here we expand the earlier results by doing the first statistical

Abstract. The coupling of the atmosphere to the space environment has become recognized as an important driver of atmospheric chemistry and dynamics. In order to quantify the effects of particle precipitation on the atmosphere, reliable global energy inputs on spatial scales commensurate with particle precipitation variations are required. To that end, we have validated the Special Sensor Ultraviolet

This study analyses the observations of a new type of small-scale aurora-like feature, which is further referred to as fragmented aurora-like emission(s) (FAEs). An all-sky camera captured these FAEs on three separate occasions in 2015 and 2017 at the Kjell Henriksen Observatory near the arctic town of Longyearbyen, Svalbard, Norway. A total of 305 FAE candidates were identified. They seem to appear

In this paper, we study the response of the mesosphere–lower thermosphere (MLT) to sudden stratospheric warmings (SSWs) and the activity of planetary waves (PWs). We observe the 557.7 nm optical emission to retrieve the MLT wind and temperature with the only Fabry–Perot interferometer (FPI) in Russia. The FPI is located at the mid latitudes of eastern Siberia within the Tory Observatory (TOR) at the

Ground-based observations show a phase shift in semi-annual variation of excited hydroxyl (OH∗) emissions at mid-latitudes (43∘ N) compared to those at low latitudes. This differs from the annual cycle at high latitudes. We examine this behaviour by utilising an OH∗ airglow model which was incorporated into a 3D chemistry–transport model (CTM). Through this modelling, we study the morphology of the

The lower-thermosphere–ionosphere (LTI) system consists of the upper atmosphere and the lower part of the ionosphere and as such comprises a complex system coupled to both the atmosphere below and space above. The atmospheric part of the LTI is dominated by laws of continuum fluid dynamics and chemistry, while the ionosphere is a plasma system controlled by electromagnetic forces driven by the magnetosphere