Adapting Empirical Electron Density Models to Disturbed Conditions
Abstract
Three dimensional and time dependent electron density models are used for various tasks in connection with the transionospheric propagation of radio waves. If not "updated" the usual empirical electron density models provide monthly median conditions. In general "updating' means replacing map values for the F2 peak density (and peak height) by actual values. If this is done for isolated height profiles of electron density we need no further modification. However, realistic updating for propagation parameters calculated along a slant ray path (e.g., from a satellite transmitter or from an extraterrestrial source to a ground receiver) needs updating along the entire ray path. Assessment studies need slant electron content calculation for many rays. Therefore we replace the monthly median "maps" by "data grids". Presently, the data grids are based on hourly data and have a grid spacing of 2.5 deg. in latitude and 5 deg. in longitude. This grid resolution is not sufficient to resolve smaller scale structures like the main trough of the F layer and the time intervals of one hour are not well suited to deal with dynamic disturbances, e.g., with the wavelike Traveling Ionospheric Disturbances (TIDs) or with magnetic storm related disturbances. Therefore we have developed a "modulation method" which adds smaller scale and dynamic structures by multiplying the background (= data grid driven) model with sub-models for these structures.
- Publication:
-
Planetary Radio Emissions VI
- Pub Date:
- 2006
- Bibcode:
- 2006pre6.conf..281L
- Keywords:
-
- Ionosphere;
- electron density;
- Earth (Planet);
- disturbances