Magnetospheric control of the energy input into the thermosphere

Abstract

A thermospheric photochemical model has been used in conjunction with satellite observations of nitric oxide to determine the flux of precipitating electrons into the thermosphere in the northern auroral region. Satellite measurements have shown that electron precipitation occurs predominantly between 1800 and 2400 hours magnetic local time. This time dependence has been incorporated into the thermospheric model calculation of nitric oxide density. Polar displays of the results of the model calculations show that the electrons deposit their energy between geomagnetic latitudes 60°-70°N. The longitudinal distribution is asymmetric with more energy being deposited at western geomagnetic longitudes and less at eastern longitudes. A calculation for equinox conditions shows that energy input as a function of longitude is 50% greater at 90°W that at 90°E. Therefore, the tilted, offset magnetic dipole field of the Earth seems to be controlling the precipitation of electrons in the northern auroral region.