资源环境科技发展态势分析平台

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 Epm and Epv obey lognormal distributions and possess narrowly clustered small values in summer but widely spread large values in winter. Epm and Epv 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 Epm during wintertime occur whenMcMurdo is well inside the polar vortex. Monthly mean Epm 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 Epm is mainly caused by critical level filtering that dissipates most gravity waves in summer. Epm 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 to strong surface and stratospheric winds, but minimal rotation angle of background winds. These findings imply that primary wave sources near the surface and secondary wave sources in the stratosphere could both exist, while background winds play a role of filtering certain wave spectra, Doppler-shifting vertical wavelengths, and therefore controlling wave propagation and dissipation. The complex interplay of wave source, dissipation, and saturation gives rise to what are observed in the current paper. These important observational facts help model simulations to narrow down the wave sources.