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Delayed response of the ionosphere to solar EUV variability (DRIVAR)


DFG JA836/33-1 (2016-2019)

SHK gesucht
Student Assistant position available


The ionospheric plasma reacts on solar EUV and UV variations in the course of the solar rotation with a time delay of 1-2 days. This delay is assumed to be owing to transport processes from the lower ionosphere to the F region, but only limited modeling has been performed so far to prove this hypothesis.

Within DRIVAR, the processes responsible for the ionospheric delay will be investigated through comprehensive data analyses and modeling. Different kinds of solar proxies as well as spectral EUV and UV fluxes from satellite observations will be used and analyzed together with ionospheric parameters from GPS radio occultations and ionosondes, and, providing both global and high-resolution coverage, GPS total electron content maps. In particular, the ionospheric delay will be analyzed at different time scales (short-term, solar rotation, seasonal time scale), and the regional dependence of the delay will be analyzed.

The DRIVAR results will provide more insight into ionospheric processes in general, and will be most valuable for ionospheric applications in forecasting ionospheric weather, e.g. for the use in GNSS error analyses and predictions.

Due to the complex character of numerous interacting processes in the thermosphere and ionosphere numerical modeling is required to physically understand the basic processes contributing to the delay. We shall use the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics (CTIPe) model to simulate the delay and, through sensitivity experiments, investigate and analyze in detail the processes that lead to the observed delay.
Filtered time series
Example of normalized SDO/EVE integrated EUV fluxes and global mean TEC, additionally filtered in the 25-29 days period range. From Jacobi et al., 2016.
Ionospheric delay
Lagged correlation of EUV index and global ionospheric total electron content. From Jacobi et al., 2015.



Cooperation partner: DLR - Institute of Communications and Navigation

Publications related to the project:

Jacobi, Ch., N. Jakowski, G. Schmidtke, and T.N. Woods, 2016: Delayed response of the global total electron content to solar EUV variations, Adv. Radio Sci., 14, 175-180, doi:10.5194/ars-14-175-2016.

Jacobi, Ch., C. Unglaub, G. Schmidtke, Schäfer, and N. Jakowski, 2015: Delayed response of global ionospheric electron content to EUV variations derived from combined SolACES-SDO/EVE measurements, Rep. Inst. Meteorol. Univ. Leipzig, 53, 1 - 10.

Jacobi, Ch., C. Unglaub, G. Schmidtke, M. Pfeifer, R. Schäfer, R. Brunner, T. Woods, und N. Jakowski, 2015: Delayed response of global TEC to ionization variations seen from combined SolACES-SDO/EVE solar EUV spectra, Proc. 7. Workshop "Solar Influences on the Magnetosphere, Ionosphere and Atmosphere", 1.-5.6.2015, Sunny Beach, 29-32, ISSN 2367-7570 (pdf).


Last update 28 June 2017 by Ch. Jacobi