Electron Density Models With "modulations" For Smaller Scale Structures
Abstract
Regional and global electron density models take into account larger scale spatial structures only. "Modulation" can be used to add smaller scale features: M(h,,,t) = L(h,,,t) × S1(h,,,t) × S2(h,,,t) × ···Sn(h,,,t) M: resulting electron density distribution, L: large scale model, S1 ···Sn: modulat- ing models for the smaller scale structures; h: height, ,: geographic coordinates, t: Universal Time. There are no restrictions to the nature of the large scale model provided it takes height and horizontal coordinates as input. Examples are models of the "profiler" type which use large scale "maps" for profile anchor points (e.g., E, F1, F2 peak properties from ionosonde parameters) like the International Reference Ionosphere (IRI) or the "family" of models developed at Trieste and Graz, NeQuick, COSTprof and NeUoG-plas. Typical examples for smaller scale structures are ridges, troughs and wavelike disturbances. The advantage of modulation by multiplication is that there is no danger to get zero or negative values of electron density as long as the background and modulations are > 0 everywhere. For each modulation model unity means "undisturbed". We present examples for three types of modulations. (1) For the main trough of the F region a model based on Dynamics Explorer 2 (DE2) insitu measurements of electron density. Since the position of the trough minimum depends on invariant magnetic latitude our model troughs are automatically magnetic field aligned. (2) Three dimensional and time dependent model for Large Scale TIDs with thermospheric sources (source points in the auroral zone) and for smaller scale TIDs with arbitrary apparant ionospheric source points. (3) Two dimensional and time dependent model for smaller scale wavelike distur- bances with arbitrary source points. Since amplitudes and phases of the disturbances are independent of height such a modulation is useful for (slant and vertical) electron content or for electron density in a given height, not for profile modulation.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.4929L