- Global sporadic E occurrence for boreal winter 2008/2009 (upper panels) and summer 2009 (lower panels). Left: vertical and time-integrated geographic distribution of sporadic E occurrence rates. Middle: Local time distribution of zonal mean sporadic E occ
- © C. Arras (GFZ)
Coupling processes between the ionosphere and the
neutral atmosphere play an important role for the dynamics of the
upper atmosphere. Recent progress in understanding the related
processes has been achieved since low-Earth orbiting satellites
provide continuous accurate measurements of thermospheric and
ionospheric parameters like mass density, zonal winds and electron
density profiles, respectively. Within this project, we plan to
observe the global sporadic E occurrence in quantity and also in its
quality. The study will be based on GPS radio occultation measurements
performed by the satellites CHAMP, GRACE, TerraSAR-X, TanDEM-X and
FORMOSAT-3/COSMIC. Since the launch of the CHAMP satellite in 2002,
there are currently more than 5 million of radio occultation profiles
available. This fact allows to investigate sporadic E properties in a
high spatial resolution as well as to perform statistical trend
analysis of sporadic E occurrence. It is planned to extent the
currently used sporadic E detection algorithm in order to receive
additional information on sporadic E intensities. Global information
on sporadic E layer intensities are not available yet and will be
provided for the first time from radio occultation measurements. It
can be used to look for changes in the sporadic E layer behavior
itself and also in the connection between sporadic E parameters and
other geophysical parameters like the decreasing strength of Earth’s
magnetic field and solar cycle dependence of atmospheric tides, meteor
influx and ionospheric phenomena, as e.g., equatorial plasma
Project proposers: Dr. Christina Arras (GFZ) , Prof. Jens Wickert (TUB/GFZ) 
Project lead: Dr. Christina Arras (GFZ) 
 Arras, C., J. Wickert, C. Jacobi, S. Heise, G. Beyerle, and T. Schmidt (2008): A global climatology of ionospheric irregularities derived from GPS radio occultation, Geophys. Res. Lett., 35, L14,809, doi:10.1029/2008GL034158.
 Arras, C., C. Jacobi, and J. Wickert (2009): Semidiurnal tidal signature in sporadic E occurrence rates derived from GPS radio occultation measurements at higher midlatitudes, Ann. Geophys., 27, 2555–2563.
 Arras, C., C. Jacobi, J. Wickert, S. Heise, and T. Schmidt (2010): Sporadic E signatures revealed from multi-satellite radio occultation measurements, Adv. in Radio Sci., 8, 225–230, doi:10.5194/ars-8-225-2010.
 Arras, C. (2010): A global Survey of Sporadic E Layers based on GPS Radio Occultations by CHAMP, GRACE and FORMOSAT-3/COSMIC, PhD thesis, University of Leipzig.
 Arras, C., J. Wickert, C. Jacobi, G. Beyerle, S. Heise, and T. Schmidt (2012):Global sporadic E layer characteristics obtained from GPS radio occultation measurements, Springer, F.-J. Lübken, Dordrecht, The Netherlands.