Properties of the main trough of the F region derived from Dynamic Explorer 2 data

Abstract

In winter and equinoctial season nights, the main trough of the F region is an important stable structure of the ionosphere at the border between mid and high latitudes. Therefore it has to be taken into account in modelling and mapping approaches. Werner and Prölss (1995) derived a model for the position of the trough minimum which has found wide acceptance. The model is based on in-situ electron density data measured aboard the low orbiting Dynamic Explorer satellite DE 2 (1981-1986). We present results for other properties of the main trough derived from the same data set. These results are sufficiently good for modelling purposes which need reliable information on the depth, the equatorward and poleward width and the steepness of the walls of the trough. Because of the eccentric orbit of DE 2 (orbit height between about 300-1000 km) it was necessary to «project» observed electron densities to the peak of the F 2 layer. This was done by means of the electron density model COSTprof. The database was restricted to those cases for which the height of DE 2 was below 700 km. Examples are shown for «typical» troughs observed under various conditions.