Comparison of the Measured and Modelled Electron Densities and Temperatures in the Ionosphere and Plasmasphere during 20±30 January, 1993

Abstract

We present a comparison of the electron density and temperature behaviour in the ionosphere and plasmasphere measured by the Millstone Hill incoherent-scatter radar and the instruments on board of the EXOS-D satellite with numerical model calculations from a time-dependent mathematical model of the Earth's ionosphere and plasmasphere during the geo-magnetically quiet and storm period on 20±30 January, 1993. We have evaluated the value of the additional heating rate that should be added to the normal photoelectron heating in the electron energy equation in the daytime plasmasphere region above 5000 km along the magnetic ®eld line to explain the high electron temperature measured by the instruments on board of the EXOS-D satellite within the Millstone Hill magnetic ®eld ¯ux tube in the Northern Hemisphere. The additional heating brings the measured and modelled electron temperatures into agreement in the plasmasphere and into very large disagreement in the ionosphere if the classical electron heat ¯ux along magnetic ®eld line is used in the model. A new approach, based on a new e€ective electron thermal conductivity coecient along the magnetic ®eld line, is presented to model the electron temperature in the ionosphere and plasmasphere. This new approach leads to a heat ¯ux which is less than that given by the classical Spitzer-Harm theory. The evaluated additional heating of electrons in the plasmasphere and the decrease of the thermal conductivity in the topside ionosphere and the greater part of the plasma-sphere found for the ®rst time here allow the model to accurately reproduce the electron temperatures observed by the instruments on board the EXOS-D satellite in the plasmasphere and the Millstone Hill incoherent-scatter radar in the ionosphere. The e€ects of the daytime additional plasmaspheric heating of electrons on the electron temperature and density are small at the F-region altitudes if the modi®ed electron heat ¯ux is used. The deviations from the Boltzmann distribution for the ®rst ®ve vibrational levels of N 2 (v) and O 2 (v) were calculated. The present study suggests that these deviations are not signi®cant at the ®rst vibrational levels of N 2 and O 2 and the second level of O 2 , and the calculated distributions of N 2 (v) and O 2 (v) are highly non-Boltzmann at vibrational levels v > 2. The resulting e€ect of N 2 (v > 0) and O 2 (v > 0) on NmF2 is the decrease of the calculated daytime NmF2 up …

Cite this paper

@inproceedings{Pavlov1993ComparisonOT, title={Comparison of the Measured and Modelled Electron Densities and Temperatures in the Ionosphere and Plasmasphere during 20±30 January, 1993}, author={Andrey V. Pavlov and Tomoka Abe and K Oyama}, year={1993} }