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Published in

Wiley, Journal of Geophysical Research. Space Physics, 3(121), p. 2522-2530, 2016

DOI: 10.1002/2015ja022169

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Effects of the equatorial ionosphere anomaly on the interhemispheric circulation in the thermosphere: EFFECTS OF EIA ON MERIDIONAL CIRCULATION

This paper is available in a repository.
This paper is available in a repository.

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Data provided by SHERPA/RoMEO

Abstract

We investigate the inter-hemisphere circulation at the solstices, in order to understand why O/N2 is larger in the northern hemisphere winter than in the southern hemisphere winter. Our studies reveal that the equatorial ionosphere anomaly (EIA) significantly impacts the summer-to-winter wind through plasma-neutral collisional heating, which changes the summer-to-winter pressure gradient, and ion drag. Consequently, the wind is suppressed in the summer hemisphere as it encounters the EIA but accelerates after it passes the EIA in the winter hemisphere. The wind then converges due to an opposing pressure gradient driven by Joule heating in auroral regions, produces large O/N2 at subauroral latitudes. This EIA effect is stronger near the December solstice than near the June solstice because the ionospheric annual asymmetry creates greater meridional wind convergence near the December solstice, which in turn produces larger O/N2 in the northern hemisphere winter than in the southern hemisphere winter.