SMF2 global model of F2 layer peak maximum from satellite and ground-based observation

Brief description

The global median model SMF2 (Satellite Model of the F2 layer) of the ionospheric F2-layer height maximum (h_mF2) is presented. In the new model the large dataset of radio occultation measurements (3 200 000 N(h)-profiles) obtained in the CHAMP, GRACE and COSMIC experiments for the low solar activity and about 200 000 N(h)-profiles obtained from topside sounding onboard the Intercosmos-19 for high solar activity were used. Ground-based ionospheric sounding data were used mainly for comparison and validation. Modeling of the spatial dependencies is based on expansion of these dependencies in series by a system of orthogonal functions [Chernyshov, Vasilyeva, 1973]. Temporal dependence, as a function of Universal Time (UT), is described by a Fourier expansion. Inputs of the model are: geographical coordinates, month number and F_10.7A solar activity index. The model is designed for quiet geomagnetic conditions (K_Ò= 2). SMF2 agrees well with the International Reference Ionosphere model [Bilitza et al., 1979; Bilitza, Reinish, 2008] in those regions, where the ground-based ionosonde network is dense. Maximal difference between the models is found in the equatorial belt, over the oceans and the polar caps. Standard deviation of the radio-occultation and Digisonde data from the predicted SMF2 median is 10–16 km for all seasons, against 26.6 km for IRI-2012 (http://omniweb.gsfc.nasa.gov/vitmo/iri2012_vitmo.html). Average relative deviations are 3–4 times less than for IRI-2012, 3–4% against 9–12%. Therefore, the proposed h_mF2 model is more accurate than IRI-2012.

Acknowledgements

The authors are grateful to sponsors and operators of the FORMOSAT-3/COSMIC mission; Taiwan’s National Science Council and National Space Organization (NSPO), the US National Science Foundation (NSF), National Aeronautics and Space Administration (NASA), National Oceanic and Atmospheric Administration (NOAA) and the University Corporation for Atmospheric Research (UCAR). The authors would like to give thanks to sponsors and operators of the CHAMP and GRACE missions; Deutsches GeoForschungsZentrum (GFZ) Potsdam, German Aerospace Center (DLR), and the US National Aeronautics and Space Administration (NASA). The authors are also grateful to NGDC for disseminating historical ionosonde data via SPIDR.

References

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• Karpachev A.T., Shubin V.N., Telegin V.A. and Tsybulya K.G. SMF2 global model of F2 layer peak maximum from satellite and ground-based observation: initial data. Journal of Atmospheric and Solar-Terrestrial Physics (in print)