Bibliography

Traits of sub-kilometre F-region irregularities as seen with the Swarm satellites

During the night, in the F-region, equatorial ionospheric irregularities manifest as plasma depletions observed by satellites, and they may cause radio signals to fluctuate. In this study, the distribution characteristics of ionospheric F-region irregularities in the low latitudes were investigated using 16 Hz electron density observations made by a faceplate which is a component of the electric field instrument (EFI) onboard Swarm satellites of the European Space Agency (ESA). The study covers the period from October\ 2014 to October\ 2018 when the 16 Hz electron density data were available. For comparison, both the absolute (dN_e) and relative (dN_e/N_e) density perturbations were used to quantify the level of ionospheric irregularities. The two methods generally reproduced the local-time (LT), seasonal and longitudinal distribution of equatorial ionospheric irregularities as shown in earlier studies, demonstrating the ability of Swarm 16 Hz electron density data. A difference between the two methods was observed based on the latitudinal distribution of ionospheric irregularities where (dN_e) showed a symmetrical distribution about the magnetic equator, while dN_e/N_e showed a magnetic-equator-centred Gaussian distribution. High values of dN_e and dN_e/N_e were observed in spatial bins with steep gradients of electron density from a longitudinal and seasonal perspective. The response of ionospheric irregularities to geomagnetic and solar activities was also investigated using Kp index and solar radio flux index (F10.7), respectively. The reliance of dN_e/N_e on solar and magnetic activity showed little distinction in the correlation between equatorial and off-equatorial latitudes, whereas dN_e showed significant differences. With regard to seasonal and longitudinal distribution, high dN_e and dN_e/N_e values were often found during quiet magnetic periods compared to magnetically disturbed periods. The dN_e increased approximately linearly from low to moderate solar activity. Using the high-resolution faceplate data, we were able to identify ionospheric irregularities on the scale of only a few hundred of metres.

Aol, Sharon; Buchert, Stephan; Jurua, Edward;

Published by: Annales Geophysicae      Published on: 02/2020

YEAR: 2020     DOI: 10.5194/angeo-38-243-2020

Where does the Thermospheric Ionospheric GEospheric Research (TIGER) Program go?

At the 10th Thermospheric Ionospheric GEospheric Research (TIGER/COSPAR) symposium held in Moscow in 2014 the achievements from the start of TIGER in 1998 were summarized. During that period, great progress was made in measuring, understanding, and modeling the highly variable UV-Soft X-ray (XUV) solar spectral irradiance (SSI), and its effects on the upper atmosphere. However, after more than 50years of work the radiometric accuracy of SSI observation is still an issue and requires further improvement. Based on the extreme ultraviolet (EUV) data from the SOLAR/SolACES, and SDO/EVE instruments, we present a combined data set for the spectral range from 16.5 to 105.5nm covering a period of 3.5years from 2011 through mid of 2014. This data set is used in ionospheric modeling of the global Total Electron Content (TEC), and in validating EUV SSI modeling. For further investigations the period of 3.5years is being extended to about 12years by including data from SOHO/SEM and TIMED/SEE instruments. Similarly, UV data are used in modeling activities. After summarizing the results, concepts are proposed for future real-time SSI measurements with in-flight calibration as experienced with the ISS SOLAR payload, for the development of a space weather camera for observing and investigating space weather phenomena in real-time, and for providing data sets for SSI and climate modeling. Other planned topics are the investigation of the relationship between solar EUV/UV and visible/near-infrared emissions, the impact of X-rays on the upper atmosphere, the development of solar EUV/UV indices for different applications, and establishing a shared TIGER data system for EUV/UV SSI data distribution and real-time streaming, also taking into account the achievements of the FP7 SOLID (First European SOLar Irradiance Data Exploitation) project. For further progress it is imperative that coordinating activities in this special field of solar–terrestrial relations and solar physics is emphasized.

Schmidtke, G.; Avakyan, S.V.; Berdermann, J.; Bothmer, V.; Cessateur, G.; Ciraolo, L.; Didkovsky, L.; de Wit, Dudok; Eparvier, F.G.; Gottwald, A.; Haberreiter, M.; Hammer, R.; Jacobi, Ch.; Jakowski, N.; Kretzschmar, M.; Lilensten, J.; Pfeifer, M.; Radicella, S.M.; Schäfer, R.; Schmidt, W.; Solomon, S.C.; Thuillier, G.; Tobiska, W.K.; Wieman, S.; Woods, T.N.;

Published by: Advances in Space Research      Published on:

YEAR: 2015     DOI: https://doi.org/10.1016/j.asr.2015.07.043

UV/EUV solar spectral irradiance; Instrumentation; Calibration; Modeling