Observed nocturnal gravity wave variances and zonal momentum flux in mid-latitude mesopause region over Fort Collins, Colorado, USA

Abstract

Twenty-nine nights including 275h measurements of temperature, zonal and meridional winds, and zonal momentum flux in the mesopause region were made between September 2006 and April 2007 with the Colorado State University (CSU) sodium lidar at Fort Collins, CO (40.6N, 105W). Perturbations with periods between 6min and 4h in temperature and winds were calculated and compared to the recently reported observations by a similar lidar located at Starfire Optical Range (SOR), NM (35N, 107W), showing general agreement. The seasonal means of the observed zonal momentum flux of these wave perturbations were found to be 0.12±0.46m2s−2 for the equinoctial season and −0.69±0.42m2s−2 for the winter season. These results are compared to two such observations in mid-latitude mesosphere and lower thermosphere (MLT) in the literature, i.e., lidar observation at SOR and radar observation near Kyoto, Japan (35N, 106E). Both magnitudes and signs of the CSU lidar observations are consistent with those published.