Stuttgart 2012 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 1: Erdnaher Weltraum
EP 1.4: Vortrag
Montag, 12. März 2012, 15:15–15:30, V55.02
Primary ionisation and solar heating variability of the thermosphere using satellite-borne solar EUV measurements — •Christoph Jacobi1, Claudia Unglaub1, Bernd Nikutowski2, Gerhard Schmidtke2, and Raimund Brunner2 — 1Institut für Meteorologie, Universität Leipzig, Stephanstr. 3,04103 Leipzig — 2Fraunhofer-Institut für Physikalische Messtechnik (IPM), Heidenhofstraße 8, 79110 Freiburg
Primary photoionisation of major ionospheric constituents is calculated from satellite-borne solar EUV measurements (TIMED/SEE and SolACES). Number densities of the background atmosphere are taken from the NRLMSISE-00 climatology. From the obtained ionisation rates, a proxy is calculated, which is based on the global total ionisation, and which describes more than 90% of the ionospheric response to solar EUV and its variability. The proxy is compared against the global mean ionospheric total electron content (TEC) derived from GPS data. Results for high and moderate solar activity show that at different (decadal, annual, solar rotation) time scales the proxy provides a better overall representation of global TEC than conventional solar indices like F10.7 do. Since the absorbed EUV is finally transformed into heat, EUV absorption rates can be also used to calculate the solar heating of the thermosphere, and therefore to measure part of the natural neutral upper atmosphere variability.