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Description
Auroral electrons are not energetic enough to penetrate down into the mesosphere, therefore the influence of auroral activity on the upper mesospheric temperature (~87km altitude) has not been studied extensively. Only a handful of studies have investigated the response of upper-mesospheric temperature to auroral activity, and possible temperature enhancements have been revealed in individual events.
We utilize nine seasons (October-March) of All-Sky Airglow Imager data from the Kjell Henriksen Observatory in Longyearbyen (75.24°N, geomagn. latitude) between 2016 and 2024. The rotational OH airglow temperature is derived from the ratio of the P1(2) and P1(4) molecular rotation lines. In addition, data from the Svalbard All-Sky Imager in Longyearbyen is used to identify regions of active aurora. The 557nm (auroral green line) emission brightness is used as a proxy for auroral activity. Auroral emissions contaminate the airglow spectrum and thus airglow derived temperature estimates are only reliable during times of no aurora. From the airglow images, we extract regions of interest near zenith and compare the derived temperatures before and after auroral activity for each region. We present preliminary results of one event with increased OH rotational temperature after a prolonged time of active aurora.
