Journal of geomagnetism and geoelectricity
Online ISSN : 2185-5765
Print ISSN : 0022-1392
ISSN-L : 0022-1392
Mesospheric Heating during Highly Relativistic Electron Precipitation Events
R. A. GoldbergD. N. BakerF. A. HerreroC. H. JackmanS. KanekalP. A. Twigg
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JOURNAL FREE ACCESS

1995 Volume 47 Issue 11 Pages 1237-1247

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Abstract

Highly relativistic electron precipitation (HRE) events which occur in the mid-latitude and auroral regions last 2.5 days on the average, peaking in the magnetosphere daily near local noon. Furthermore, they can recur every 27 days for several synodic solar rotation periods, and become most intense and frequent during the minimum of the solar cycle. These events are described in terms of their spatial and temporal extent and their spectral characteristics. A detailed sounding rocket study of a relatively weak event in May, 1990 at Poker Flat, Alaska gave energy depositions from which modeling calculations have yielded O3 depletion estimates in excess of 25% near 75 km altitude. These depletions would hardly affect the UV flux reaching the stratosphere below, but could alter the thermal balance in the 60-75 km altitude region in the mesosphere. Further analysis for that HRE has shown the possibility of Joule heating effects near the polar cusp of up to 3°/day depending on the magnitude of the electric field. The mesospheric heating caused by more intense events studied with SAMPEX (Solar Anomalous Magnetospheric Particle Explorer) is compared with the earlier May 1990 event to demonstrate the global impact of HRE events on the chemical and thermal characteristics of the neutral atmosphere.

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