Atmospheric gravity waves observed in OH airglow images from 78°N

Atmospheric gravity waves play an essential role in determining the global circulation and thermal balance of the atmosphere. Airglow imagers are important tools for characterizing atmospheric gravity waves in the mesopause region and there are few placed in High Arctic locations. An airglow imager was installed at the Kjell Henriksen Observatory (KHO) located close to Longyearbyen on the Norwegian Arctic archipelago Svalbard (78°N, 16°E) in November 2010. The imager has a wide band filter and also bandpass filters to obtain the intensity of two different rotational lines of the OH(6-2) vibrational band. Two winter seasons of airglow data (2010/2011 and 2011/2012) have been analyzed. From the 395 measurement days, only about 17% had clear sky periods. Analysis of the images with low auroral contamination shows that gravity waves can be detected by the imager, however the number of wave events observed were relatively few. The characteristics of the observed waves have been found by FFT analysis. By using mesospheric wind data from the nearby Nippon/Norway Svalbard Meteor Radar (NSMR), the intrinsic properties of the gravity waves have also been retrieved. The predominant propagation direction of the gravity waves observed is northwestward. Temperatures obtained from combining the observed ratio of the bandpass images and background intensity measured by a co-located spectrometer is also presented.