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

• Published in: Journal of geophysical research. Atmospheres 2018-08, Vol.123 (15), p.7910-7934
• Main Authors: Chu, Xinzhao, Zhao, Jian, Lu, Xian, Harvey, V. Lynn, Jones, R. Michael, Becker, Erich, Chen, Cao, Fong, Weichun, Yu, Zhibin, Roberts, Brendan R., Dörnbrack, Andreas
• Format: Article
• Language: English
• Subjects: Altitude; Antarctic lidar observations; Atmospheric Composition and Structure; Atmospheric Processes; Climate and Dynamics; Coefficients; Computer simulation; Correlation coefficient; Correlation coefficients; Density; Dissipation; Doppler sonar; Energy; Filtration; Flux density; Geophysics; Gravitational waves; Gravity; Gravity waves; Inertia; Inertia gravity waves; Interannual variations; Iron; Lidar; lognormal distributions; Lower thermosphere; Meandering; Middle Atmosphere Dynamics; Middle Atmosphere: Constituent Transport and Chemistry; Middle Atmosphere: Energy Deposition; Minima; Natural Hazards; Polar Meteorology; Polar vortex; Potential energy; potential energy density; Profiles; Remote Sensing; Remote Sensing and Disasters; Rotation; Saturation; Seasonal variation; Seasonal variations; Spectra; Static stability; Stratosphere; Stratospheric Dynamics; Stratospheric gravity waves; Stratospheric winds; Summer; Temperature data; Thermosphere; Troposphere; Vertical distribution; Vertical stability; Wave dissipation; Wave energy; Wave generation; Wave propagation; Wave spectra; Wavelengths; Wind speed; Winds; Winter
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1029/2017JD027386

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 (Epm), potential energy volume density (Epv), vertical wave number spectra, and static stability N2 in the stratosphere 30–50 km. Epm (Epv) profiles increase (decrease) with altitude, and the scale heights of Epv indicate stronger wave dissipation in winter than in summer. Altitude mean E¯pm and E¯pv obey lognormal distributions and possess narrowly clustered small values in summer but widely spread large values in winter. E¯pm and E¯pv 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 N2¯ 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 E¯pm during wintertime occur when McMurdo is well inside the polar vortex. Monthly mean E¯pm 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 E¯pm is mainly caused by critical level filtering that dissipates most gravity waves in summer. E¯pm 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. Plain Language Summary Persistent and dominant inertia‐gravity waves (IGWs) are meandering around McMurdo, Antarctica, from the stratosphere to the lower thermosphere all year round. However, the wave sources are still mysterious and in a hot debate. This paper represents a significant step forward in the wave source searching by the following intriguing findings: Large wave energy occurs when McMurdo is deep inside the polar vortex, consistent with the fact that the vertical propagation angle of McMurdo IGWs is shallow so that wave sources are not local; potential energy density shows the repeated seasonal patterns with summer minima and winter maxima, and larger energy density corresponds