The topside ionosphere embraces the region extending from the F2-layer electron density peak to the overlying plasmasphere. In this region the electron density monotonically decreases at a vertical rate driven by the plasma scale height, which in turn depends on both the plasma chemical composition and the physical state. Since an accurate and thorough knowledge of the plasma chemical and physical properties at these altitudes is not available with the required spatial and temporal coverage, an effective plasma scale height is usually inferred from topside electron density measurements and used for empirical modelling purposes.

In this work, we aim at characterizing the effective plasma scale height (H₀) above the F2-layer peak  through in-situ electron density (N_e) observations by Langmuir Probes (LPs) on-board the China Seismo-Electromagnetic Satellite (CSES-01). Additional information is given by the International Reference Ionosphere (IRI) model. CSES-01 is a sun-synchronous satellite flying with an orbital inclination of 97.4°, an altitude of ~500 km, and descending and ascending nodes are at ~14 local time (LT) and ~02 LT, respectively. Calibrated CSES-01 LPs N_e data recorded in the years 2019-2021 provides the information in the topside ionosphere, while IRI provides the N_e values at the F2-layer peak (NmF2) for the same time, latitude, and longitude sounded by CSES-01. These two N_e set of values are used as anchor points to infer H₀ through the topside representation given by the NeQuick model. By exploiting the CSES-01 dataset for the years 2019-2021 we deduced the global H₀ behavior for daytime (~14 LT) and nighttime (~02 LT) conditions, for low solar activity conditions. Results obtained with CSES-01 observations are compared and validated with corresponding ones provided by COSMIC-1 radio occultation measurements for similar diurnal and solar activity conditions.

How to cite: Pezzopane, M., Pignalberi, A., Coco, I., Consolini, G., D'Angelo, G., De Michelis, P., Giannattasio, F., Piersanti, M., and Tozzi, R.: Topside ionosphere effective plasma scale height characterization through CSES-01 satellite Langmuir Probes observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6633, https://doi.org/10.5194/egusphere-egu23-6633, 2023.

On 21 June 2020, an annular solar eclipse pass over Africa, Europe, and Asia.  When the moon’s shadow sweeps, the solar radiation is blocked out and leads to weak photochemical effects and other variations on the ionosphere.  The ion/electron temperature, density, and the ion vertical drift velocity measured by multi-satellites have been estimated and analyzed.  EFI (Electric Field Instrument) onboard Swarm with a circular orbit of 88° inclination and 530 km altitude provides the data of electron temperature and density.  IVM (ion velocity meter) onboard FORMOSAT-7/COSMIC-2 (F7/C2) with a circular orbit of 24° inclination and 550 km altitude supplies information on the ion temperature, density, and ion vertical drift velocity.  IVM onboard Ionospheric Connection Explorer (ICON) with a circular orbit of 27° inclination and 579 km altitude offers the same parameters as F7/C2.  On the event day, a total of 9 paths of those satellites passed through the greatest eclipse path, 6 from F7/C2, 2 from ICON, and 1 from Swarm.  Referencing one-month data of each satellite path, both ion and electron temperature decrease about 500K after the maximum contact.  Three of the four solar eclipse signatures in the ion density are observed, including pre-ascensions, major depressions, and sunset ascensions.  Moreover, the ion drift velocity tends to be downward around the maximum contact.  Detailed results will be presented and discussed.

How to cite: Kao, T.-H. and Liu, J.-Y.: Swarm, FORMOSAT-7/COSMIC-2, and ICON ionospheric observations during the annular solar eclipse on 21 June 2020, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-596, https://doi.org/10.5194/egusphere-egu23-596, 2023.

How to cite: Krauss, S., Kroisz, S., Drescher, L., Scherf, M., Lammer, H., Temmer, M., and Strasser, A.: Exploration of the divergent effects of CMEs on low Earth orbiting satellites – current status of the project ESPRIT, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5590, https://doi.org/10.5194/egusphere-egu23-5590, 2023.

Proton auroras are produced by energetic protons that precipitate, undergo charged exchange, and subsequently emit hydrogen lines before they are ionized again. When viewed from space, the spectral shape of proton auroras is expected to shift to longer wavelengths (red shift) due to the Doppler effect. Reports on space-based observations of Doppler shift of hydrogen Lyman-alpha spectral line associated with auroral proton precipitation are still rare. The Special Sensor Ultraviolet Spectrographic Imager (SSUSI) on board the Defense Meteorological Satellite Program (DMSP) series is a line scanning imaging spectrograph covering the far ultraviolet (FUV) spectrum from ~112 to 185 nm with 160 spectral bins. Under the spectragraph mode, SSUSI is supposed to be able to provide information about proton auroral precipitation. Here we present results from our first attempt to extract Doppler shift of Lyman-alpha spectral line of Hydrogen from the SSUSI data. We show red-shifted Lyman-alpha spectra observed by SSUSI whenever the DMSP satellite traverses the auroral oval, especially during geomagnetic active time. In general, a larger red shift appears in the nightside than dayside oval crossing and in the equatorward than poleward half of the oval. These are generally consistent with in situ auroral particle observations reported previously. Thus DMSP/SSUSI provides an alternative means to monitoring the energetic of proton precipitation.

How to cite: Liou, K., Paxton, L., Zhang, Y., and Schaefer, R.: Doppler shifted auroral Lyman-alpha spectra observed by DMSP/SSUSI, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8308, https://doi.org/10.5194/egusphere-egu23-8308, 2023.

One of the objectives of the PITHIA-NRF project is to provide effective and convenient access to the best European research facilities for observations of the upper atmosphere. The individual PITHIA-NRF nodes provide access to key experimental and data processing facilities for studies and modeling of physical processes acting in the Earth’s plasmasphere, ionosphere and thermosphere. The facilities connected to the nodes are geographically distributed over Europe, as well as internationally, and their expertise and dedication span over a wide range of topics within the research area. This variety of expertise and techniques, all with the purpose of studying specific parts of the ionosphere-thermosphere-plasmasphere (ITP), allows for common ground and a platform for a better understanding of the many different complex couplings and interactions within ITP as well as between ITP and the magnetospheric/space environment.

The access to the nodes is organised through the Trans-National Access (TNA) programme and provides an opportunity for researchers and other users to execute and carry out their own projects at one of the twelve PITHIA-NRF research facilities. Users can request either physical access (a one-week visit at the node with support at the site) or remote access (one-month access from a distance with weekly support). Users with granted projects will learn how to work with the facilities during the complete access cycle, from setting up a campaign to the collection, analysis and finally exploitation of data with the help of tools and services provided by PITHIA-NRF via the e-science centre. There is also a possibility of virtual access - typically referring to access to data and digital tools. There are no restrictions to the number of simultaneous users, and no selective process is needed for this type of Access. PITHIA-NRF e-science centre is currently under development, and it will be offering more and more tools with time. Access to the TNA programme can be requested by scientific users from academia, Small and Medium Enterprises, large companies and public organizations by proposing a scientific project and applying through the PITHIA-NRF website: https://pithia-nrf.eu/

How to cite: Häggström, I. and Mihalikova, M.: PITHIA-NRF offers Trans-national access to European upper atmosphere research facilities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9013, https://doi.org/10.5194/egusphere-egu23-9013, 2023.

The chemical release at an ionospheric altitude allows us to investigate the plasma processes in the ionosphere-magnetosphere system. The numerical models of the expansion of the artificial plasma clouds produced by the chemical release have been developed. Previous works revealed that, for a barium release with no directional velocity in the uniform background, the neutral barium cloud expands radially, while the ionized barium (Ba+) cloud produced by photoionization of the neutral cloud expands into an elliptic structure along the direction of the magnetic field. And they also revealed that the background ionospheric and initial release conditions primarily affect the cloud’s behavior. Barium Release Optical and Radio rocket (BROR) mission plans to conduct several barium releases at different ionospheric altitudes between 120 and 180 km, which are much lower than past experiments, aiming to study small-scale processes and structure in the auroral ionosphere by means of an active modification of the ionosphere. Since the atmospheric composition of ion and neutral spices and their parameters vary significantly around the BROR target region, i.e., from the E region to the bottom of the F region, we took into these altitudinal differences in our model. We revealed that the altitudinal difference contributes significantly to the Ba+ cloud’s expansion, especially with no background and release velocity, producing a teardrop shape. We also found that the Ba+ cloud at lower altitudes expands slowly, confining to a relatively small area due to the higher collision frequency. In comparison, the Ba+ cloud at a higher altitude stretches faster along the magnetic field and ends up with larger radii due to the lower collision frequency and higher diffusion rate. In this presentation, we show numerical results for the different release conditions at several altitudes in the E and F region and discuss the effects of different release conditions at various altitudes.

How to cite: Yokoyama, Y. and Sergienko, T.: Three-dimensional modeling of barium cloud's expansion in the E and F regions: Applying for BROR mission., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10080, https://doi.org/10.5194/egusphere-egu23-10080, 2023.

A FORMOSAT-5 satellite was launched on 25 August 2017 CST into a 98.28° inclination sun-synchronous circular orbit at 720 km altitude along the 1030/2230 local time sectors.  The orbital coverage provides a great opportunity to survey terrestrial ionosphere from equatorial to polar region every two days.  Advanced Ionospheric Probe (AIP) is a piggyback science payload developed by National Central University for the FORMOSAT-5 satellite to measure ionospheric plasma concentrations, velocities, and temperatures.  It is also capable of measuring ionospheric plasma density irregularities at a sample rate up to 8,192 Hz over a wide range of spatial scales.  In this poster, global ion density distributions measured by FORMOSAT-5/AIP in the pre-midnight sector can be averaged monthly and seasonally from in-situ measurement since November 2017.  Equatorial wave-4 patterns, plasma depletion bays, and mid-latitude plasma density enhancement are clearly observed from the distributions and varied with season and solar cycle.  It is adversely indicated that FORMOSAT-5/AIP can provide high quality data to identify long-term ionospheric ion density variations.

How to cite: Chao, C.-K.: Global Ion Density Distributions Observed by Advanced Ionospheric Probe Onboard FORMOSAT-5 Satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17033, https://doi.org/10.5194/egusphere-egu23-17033, 2023.

This paper studies the hemispheric asymmetry of the total electron content (TEC) by means of the Global Ionosphere Map (GIM), which has been routinely publishing every 2 hours by the Center for Orbit Determination in Europe (CODE) during 1999-2019.  The study period including the solar cycles 23 and 24 allows us globally uniformly examine the ionospheric asymmetry phenomenon of the GIM TEC in the different solar activities.  At each time point, summations of the GIM TEC at low-, mid-, and high-latitude in the northern and southern hemispheres are computed.  Results reveal the maximum summations of the GIM TEC occurring in April or November and the minimum summations of the GIM TEC occurring in July, which indicates the extreme TEC values in each year are not at the equinox or solstice.  We compare the sums of the two hemispheres in various local times, months, and solar activities.  By computing the annual magnitude of the asymmetry phenomenon, it is found that the asymmetric phenomenon is more prominent during the low solar activity, although its fluctuation is proportional to the F10.7 index.  We further study the asymmetry phenomenon in various latitudes and find the latitudes with prominent signatures.

How to cite: Chang, Y.-C. and Liu, J.-Y.: Hemispheric Asymmetries in the Ionospheric Total Electron Content during 1999-2019, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-597, https://doi.org/10.5194/egusphere-egu23-597, 2023.

The paper presents results of the analysis of the TID activity and changes in the regular ionospheric variability observed over central and eastern Europe during geomagnetically quiet days, and during CME and CIR/HSSS-related storms. We analyzed main ionospheric parameters retrieved from manually scaled ionograms obtained at several central and eastern European locations and incoherent scatter radar data (Kharkiv, Ukraina). Large scale traveling ionospheric disturbance (LSTIDs) are thought to be mostly originated in the auroral zone in consequence of increased geomagnetic activity. Although there have been numerous studies of TIDs, current knowledge is often based on observing only limited set of parameters and two-dimensional characteristics (for example, total electron content by GNSS receivers or airglow brightness by all-sky imagers). Incoherent scatter technique enables simultaneous studies of altitudinal characteristics of TIDs in several parameters like electron density, electron and ion temperature and plasma drift, thus providing important information needed to investigate TIDs, their propagation and consider probable association of TIDs with their sources. This technique also yields all components of wave vector, provided that the radar has the ability to operate in multi-beam mode. In order to obtain quantitative information on the likeliness and morphology of the passage of LSTIDs over Europe at about 40 events were examined lasting between 8 and 24 hours each. In this paper we focused mainly on a couple of geomagnetic disturbances (depending on the incoherent scatter radar data availability). Most of the observed storm-related TIDs had periods of 60-180 min (LSTIDs). During the analyzed storms we also observed extraordinary spreads and plasma bubbles at the F region heights.

How to cite: Buresova, D., Panasenko, S. V., D. Aksonova, K., Bogomaz, O. V., Zhivolup, T. G., and Koloskov, A. V.: Multiinstrumental observations of traveling ionospheric disturbances over Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6707, https://doi.org/10.5194/egusphere-egu23-6707, 2023.

In this work Total Electron Content (TEC) during the moderate geomagnetic storm of 27 February 2014 over the Iberian Peninsula and Northern Africa is analysed. The data used are coming from GNSS derived TEC and ROTI from several receiver stations from Spain, Portugal and Morocco. Maps of TEC are developed to study its evolution before, during and some days after the main phase of the storm. This study shows that before the storm, i.e. during quiet geomagnetic conditions, a northern crest of the Equatorial Ionosphere Anomaly (EIA) is located in Western North Africa with low gradients and values of TEC. During the main period of the storm, this northern crest of the EIA is also located in the Western North Africa with larger gradients that affect the southern part of the Iberian Peninsula. These gradients are present both in latitude and longitude. They are observed exclusively over this region but not seen in the rest of Southern Europe. In addition, increased values of ROTI from GNSS stations located in Southern Spain are also found during the storm, but not observed northwards and eastwards of that region. Since the Iberian Peninsula is located in a mid-latitude area not expected to be influenced by the EIA, these findings seem to indicate that the Southern part of the Peninsula could be influenced by the EIA during disturbed geomagnetic conditions.

How to cite: Campuzano, S. A., Migoya-Orué, Y., Radicella, S. M., Delgado-Gómez, F., Herraiz, M., and Rodríguez-Caderot, G.: Total Electron Content evolution during the 27 February 2014 storm over the Iberian Peninsula and Northern Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16331, https://doi.org/10.5194/egusphere-egu23-16331, 2023.

Solar wind Alfvén waves in high-speed streams from coronal holes modulate dayside ionospheric convection and currents, including auroral electrojets [1]. They generate large- to medium-scale atmospheric gravity waves (AGWs) propagating globally from sources in the lower thermosphere both upward and downward [2,3]. In the upper atmosphere, the AGWs drive traveling ionospheric disturbances (TIDs) observed by the Super Dual Auroral Radar Network (SuperDARN), Poker Flat Incoherent Scatter Radar (PFISR), and the GNSS total electron content (TEC) mapping technique. The horizontal equivalent ionospheric currents are estimated from the ground-based magnetometer data using an inversion technique. In the lower atmosphere, the equatorward propagating AGWs with attenuated amplitudes can be amplified upon over-reflection in the troposphere. They can release conditional symmetric instability leading to slantwise convection, latent heat release and intensification of extratropical cyclones [4,5], which in turn are a source of AGWs/TIDs. Southeastward propagating TIDs that originate from cold fronts of intensifying extratropical cyclones are observed in the detrended TEC maps, and by the multipoint and multifrequency continuous Doppler sounders in Czechia. Ray tracing AGWs in a model atmosphere supports the observations.

[1] Prikryl P., et al., Ann. Geophys., 40, 619–639, 2022. doi.org/10.5194/angeo-40-619-2022
[2] Mayr H.G., et al., Space Sci. Rev. 54, 297–375, 1990. doi:10.1007/BF00177800
[3] Prikryl, P., et al., Ann. Geophys. 23, 401–417, 2005. doi.org/10.5194/angeo-23-401-2005
[4] Prikryl P., et al., Ann. Geophys. 27, 31–57, 2009. doi:10.5194/angeo-27-31-2009
[5] Prikryl P., et al., J. Atmos. Sol.-Terr. Phys. 171, 94–10, 2018. doi:10.1016/j.jastp.2017.07.023

How to cite: Prikryl, P., Themens, D. R., Chum, J., Chakraborty, S., Gillies, R. G., and Weygand, J. M.: Atmospheric gravity waves generated by solar wind high-speed stream Alfvén waves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3911, https://doi.org/10.5194/egusphere-egu23-3911, 2023.