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Latitudinally dependent Trimpi effects: modeling and observations

Clilverd, Mark A.; Yeo, Richard F.; Nunn, David; Smith, Andy J.. 1999 Latitudinally dependent Trimpi effects: modeling and observations. Journal of Geophysical Research, 104 (A9). 19881-19887. 10.1029/1999JA900108

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Abstract/Summary

Modeling studies show that the exclusion of the propagating VLF wave from the ionospheric region results in the decline of Trimpi magnitude with patch altitude. In large models such as Long Wave Propagation Capability (LWPC) this exclusion does not occur inherently in the code, and high-altitude precipitation modeling can produce results that are not consistent with observations from ground-based experiments. The introduction to LWPC of realistic wave attenuation of the height gain functions in the ionosphere solves these computational problems. This work presents the first modeling of (Born) Trimpi scattering at long ranges, taking into account global inhomogeneities and continuous mode conversion along all paths, by employing the full conductivity perturbation matrix. The application of the more realistic height gain functions allows the prediction of decreasing Trimpi activity with increasing latitude, primarily through the mechanism of excluding the VLF wave from regions of high conductivity and scattering efficiency. Ground-based observations from Faraday and Rothera, Antarctica, in September and October 1995 of Trimpi occurring on the NPM (Hawaii) path provide data that are consistent with these predictions. Latitudinal variations in Trimpi occurrence near L=2.5, with a significant decrease of about 70% occurrence between L=2.4 and L=2.8, have been observed at higher L shell resolution than in previous studies (i.e., 2<L<3).

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1029/1999JA900108
Programmes: BAS Programmes > Pre 2000 programme
ISSN: 0148-0227
Additional Keywords: trimpi, VLF, radio waves, electrons, transmissions, ionization, lightning, magnetosphere, ionosphere
Date made live: 14 Oct 2013 08:42 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/503089

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