EISCAT Svalbard radar-derived atmospheric tidal features in the lower thermosphere as compared with the numerical modeling ATM2

• Main Authors: Takehiko Aso, Anthony Van Eyken, Phil J. S. Williams
• Format: Report
• Language: English
• Published: National Institute of Polar Research 1999
• Subjects: Svalbard; EISCAT; Advances in polar upper atmosphere research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=6277; http://id.nii.ac.jp/1291/00006277/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=6277&item_no=1&attribute_id=18&file_no=1

The EISCAT Svalbard radar (ESR) has obtained neutral wind field data down to 90 km altitude in two period runs in August 1998. This has been rendered possible by successful elimination of ground clutter echoes by the ESR staff. Features of the obtained tidal components are then comparatively studied with the ATM2 (Atmospheric Tidal Modeling Version 2) steady tidal model which assumes climatological background zonal flow. It is found that the results are fairly consistent with theoretical predictions that the diurnal component is almost evanescent with some indication of propagating characteristics, and that the semi-diurnal one is dominated by short vertical wavelength higher order mode prevalent at higher latitudes. The ter-diurnal component is also not in contradiction with non-linear interaction theory. Convincing delineation of these behaviors, however, awaits further study on the zonal wave number characteristics of relevant waves by longitudinal network collaborations.