Earth Planets Space, Vol. 64 (No. 6), pp. 531-543, 2012
doi:10.5047/eps.2011.10.016

A new global empirical model of the electron temperature with the inclusion of the solar activity variations for IRI

V. Truhlik¹, D. Bilitza^2,3, and L. Triskova¹

¹Institute of Atmospheric Physics, ASCR, Prague, 14131, Czech Republic
²George Mason University, Space Weather Laboratory, Fairfax, VA 22030, U.S.A.
³Goddard Space Flight Center, Heliospheric Physics Laboratory, Code 672, Greenbelt, MD 20771, U.S.A.

(Received August 17, 2010; Revised September 10, 2011; Accepted October 8, 2011; Online published July 27, 2012)

Abstract: A data-base of electron temperature (T_e) comprising of most of the available LEO satellite measurements in the altitude range from 350 to 2000 km has been used for the development of a new global empirical model of T_e for the International Reference Ionosphere (IRI). For the first time this will include variations with solar activity. Variations at five fixed altitude ranges centered at 350, 550, 850, 1400, and 2000 km and three seasons (summer, winter, and equinox) were represented by a system of associated Legendre polynomials (up to the 8th order) in terms of magnetic local time and the earlier introduced invdip latitude. The solar activity variations of T_e are represented by a correction term of the T_e global pattern and it has been derived from the empirical latitudinal profiles of T_e for day and night (Truhlik et al., 2009a). Comparisons of the new T_e model with data and with the IRI 2007 T_e model show that the new model agrees well with the data generally within standard deviation limits and that the model performs better than the current IRI T_e model.
Key words: Electron temperature, ionosphere, plasmasphere, empirical models, International Reference Ionosphere.