Gravity wave activity in the troposphere and lower stratosphere: An observational study of seasonal and interannual variations

Abstract

An 11 year (1998-2008) temperature and wind data set obtained over Annette Island (55.03°N, 131.57°W) is used to examine gravity wave activity and their seasonal and interannual variations in gravity wave activity. Vertical wave number spectra of normalized temperature and wind fluctuations are calculated and are compared with the predictions of gravity wave saturation models. Results indicate that there are serious discrepancies between our measurements and earlier observational results at present stage of study of vertical wave number spectra. The correlation coefficients between tropospheric and stratospheric temperature spectral parameters are very small, suggesting that the result is in agreement with previous studies. Time series of total wave energy reveal clear seasonal and interannual variations. Maximum wave energy amplitudes occur near winter of each year in the troposphere and near summer of each year in the stratosphere. Specifically, the maximum wave energy amplitudes in the troposphere show a close correspondence with the maximum occurrence rate of dynamical instability. In addition, the maximum wave energy amplitudes in the stratosphere also show a close correspondence with the maximum occurrence rate of convective instability. Key Points There are serious discrepancies between observations and model expectations Study of the seasonal and interannual variations at high latitudes is meager We discuss main excitation source of the seasonal and interannual variations ©2013. American Geophysical Union. All Rights Reserved.