Lidar Observations of Stratospheric Gravity Waves From 2011 to 2015 at McMurdo (77.84°S, 166.69°E), Antarctica: 2. Potential Energy Densities, Lognormal Distributions, and Seasonal Variations.

Five years of Fe Boltzmann lidar's Rayleigh temperature data from 2011 to 2015 at McMurdo are used to characterize gravity wave potential energy mass density ( ), potential energy volume density ( ), vertical wave number spectra, and static stability in the stratosphere 30-50 km. ( ) profiles increase (decrease) with altitude, and the scale heights of indicate stronger wave dissipation in winter than in summer. Altitude mean and obey lognormal distributions and possess narrowly clustered small values in summer but widely spread large values in winter. and vary significantly from observation to observation but exhibit repeated seasonal patterns with summer minima and winter maxima. The winter maxima in 2012 and 2015 are higher than in other years, indicating interannual variations. Altitude mean varies by ~30-40% from the midwinter maxima to minima around October and exhibits a nearly bimodal distribution. Monthly mean vertical wave number power spectral density for vertical wavelengths of 5-20 km increases from summer to winter. Using Modern Era Retrospective Analysis for Research and Applications version 2 data, we find that large values of during wintertime occur when McMurdo is well inside the polar vortex. Monthly mean are anticorrelated with wind rotation angles but positively correlated with wind speeds at 3 and 30 km. Corresponding correlation coefficients are -0.62, +0.87, and +0.80, respectively. Results indicate that the summer-winter asymmetry of is mainly caused by critical level filtering that dissipates most gravity waves in summer. variations in winter are mainly due to variations of gravity wave generation in the troposphere and stratosphere and Doppler shifting by the mean stratospheric winds.