Generation of Atmospheric Gravity Waves in the Polar Thermosphere in Response to Auroral Activity
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Atmospheric gravity wave (AGW) is a typical phenomenon in the upper atmosphere. At mid/low latitudes, climatological sources such as unstable barometric activity in the troposphere play an important role to generate AGWs in the thermosphere. While these sources are also important at high latitudes, energy input from the magnetosphere has additional large contributions to AGW generation. This paper reviews previous studies of AGWs associated with auroral activity at high latitudes. Theoretical studies have indicated that Joule/particle heating and the Lorentz force are major processes for generating AGWs in the thermosphere. Many observations show that AGWs can propagate horizontally for thousands of km from the source region. The paper summarizes equations regarding AGW generation by Joule/particle heating and the Lorentz force, and discusses the relative importance of these two processes.
KeywordsAtmospheric gravity wave Aurora High latitude Thermosphere Ionosphere
This research has been supported by a Grant-in-Aid for Scientific Research (22403010) from MEXT, Japan. We are indebted to the director and staff of EISCAT for operating the facility and supplying the data. EISCAT is an international association supported by research organizations in China (CRIPR), Finland (SA), Germany (DFG), Japan (STEL and NIPR), Norway (NFR), Sweden (VR), and the United Kingdom (STFC).
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