Bibliography

B2 Thickness Parameter Response to Equinoctial Geomagnetic Storms

The thickness parameters that most empirical models use are generally defined by empirical relations related to ionogram characteristics. This is the case with the NeQuick model that uses an inflection point below the F2 layer peak to define a thickness parameter of the F2 bottomside of the electron density profile, which is named B2. This study is focused on the effects of geomagnetic storms on the thickness parameter B2. We selected three equinoctial storms, namely 17 March 2013, 2 October 2013 and 17 March 2015. To investigate the behavior of the B2 parameter before, during and after those events, we have analyzed variations of GNSS derived vertical TEC (VTEC) and maximum electron density (NmF2) obtained from manually scaled ionograms over 20 stations at middle and low latitudes of Asian, Euro-African and American longitude sectors. The results show two main kinds of responses after the onset of the geomagnetic events: a peak of B2 parameter prior to the increase in VTEC and NmF2 (in \textasciitilde60\% of the cases) and a fluctuation in B2 associated with a decrease in VTEC and NmF2 (\textasciitilde25\% of the cases). The behavior observed has been related to the dominant factor acting after the CME shocks associated with positive and negative storm effects. Investigation into the time delay of the different measurements according to location showed that B2 reacts before NmF2 and VTEC after the onset of the storms in all the cases. The sensitivity shown by B2 during the studied storms might indicate that experimentally derived thickness parameter B2 could be incorporated into the empirical models such as NeQuick in order to adapt them to storm situations that represent extreme cases of ionospheric weather-like conditions.

Migoya-Orué, Yenca; Alazo-Cuartas, Katy; Kashcheyev, Anton; Amory-Mazaudier, Christine; Radicella, Sandro; Nava, Bruno; Fleury, Rolland; Ezquer, Rodolfo;

Published by: Sensors      Published on: jan

YEAR: 2021     DOI: 10.3390/s21217369

Geomagnetic storms; total electron content; ionospheric empirical models; NeQuick model; thickness parameter

Multivariable Comprehensive Analysis of Two Great Geomagnetic Storms of 2015

During the year 2015 two great geomagnetic storms (Dst\ \<\ -200\ nT) occurred on 17 March and 22 June. These two geomagnetic storms have similarities. They occurred during the same decreasing phase of the sunspot cycle 24. The interplanetary and magnetospheric environments were calm before the beginning of the storms. Both events were due to Coronal Mass Ejections and High-Speed Solar Wind. Variations of the solar wind velocity and the Bz component of the interplanetary magnetic field were also similar. Two key features that are different for these storms are UT time of the beginning (04:45 UT for 17 March and 18:33 UT for 22 June) and season (equinox and solstice). The comparison of the impact of the storms on the Earth ionosphere and magnetosphere has been performed using diverse parameters including global ionospheric maps of vertical total electron content, data from individual Global Navigation Satellite System receivers, ionosondes, magnetometers, and instruments from different space missions. Visualizing global ionospheric map data as the difference of vertical total electron content between consecutive days allowed understanding better the effect of the storms as a function of time of the beginning of the storm and of the season. It is shown that the presence or absence of scintillations in Global Navigation Satellite System signals during these two storms in African longitude sector is clearly related to the local time at a given station at the beginning of the storm.

Kashcheyev, A.; e, Migoya-Oru\; Amory-Mazaudier, C.; Fleury, R.; Nava, B.; Alazo-Cuartas, K.; Radicella, S.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 04/2018

YEAR: 2018     DOI: 10.1029/2017JA024900

Middle- and low-latitude ionosphere response to 2015 St. Patrick\textquoterights Day geomagnetic storm

This paper presents a study of the St Patrick\textquoterights Day storm of 2015, with its ionospheric response at middle and low latitudes. The effects of the storm in each longitudinal sector (Asian, African, American, and Pacific) are characterized using global and regional electron content. At the beginning of the storm, one or two ionospheric positive storm effects are observed depending on the longitudinal zones. After the main phase of the storm, a strong decrease in ionization is observed at all longitudes, lasting several days. The American region exhibits the most remarkable increase in vertical total electron content (vTEC), while in the Asian sector, the largest decrease in vTEC is observed. At low latitudes, using spectral analysis, we were able to separate the effects of the prompt penetration of the magnetospheric convection electric field (PPEF) and of the disturbance dynamo electric field (DDEF) on the basis of ground magnetic data. Concerning the PPEF, Earth\textquoterights magnetic field oscillations occur simultaneously in the Asian, African, and American sectors, during southward magnetization of the B_z component of the interplanetary magnetic field. Concerning the DDEF, diurnal magnetic oscillations in the horizontal component H of the Earth\textquoterights magnetic field exhibit a behavior that is opposed to the regular one. These diurnal oscillations are recognized to last several days in all longitudinal sectors. The observational data obtained by all sensors used in the present paper can be interpreted on the basis of existing theoretical models.

Nava, B.; iguez-Zuluaga, Rodr\; Alazo-Cuartas, K.; Kashcheyev, A.; e, Migoya-Oru\; Radicella, S.M.; Amory-Mazaudier, C.; Fleury, R.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 03/2016

YEAR: 2016     DOI: 10.1002/2015JA022299

Middle-and low-latitude ionosphere response to 2015 St. Patrick's Day geomagnetic storm

Nava, B; iguez-Zuluaga, Rodr\; Alazo-Cuartas, K; Kashcheyev, A; e, Migoya-Oru\; Radicella, SM; Amory-Mazaudier, Christine; Fleury, Rolland;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2016     DOI: 10.1002/2015JA022299

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