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Eastward propagating planetary waves with periods of 1–5 days in the winter Antarctic stratosphere as revealed by MERRA and lidar
Author(s) -
Lu Xian,
Chu Xinzhao,
FullerRowell Tim,
Chang Loren,
Fong Weichun,
Yu Zhibin
Publication year - 2013
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/jgrd.50717
Subject(s) - wavenumber , stratosphere , baroclinity , instability , atmospheric sciences , zonal and meridional , geology , rossby wave , climatology , latitude , middle latitudes , barotropic fluid , flux (metallurgy) , geophysics , physics , geodesy , mechanics , optics , materials science , metallurgy
This study presents the first report of planetary wave (PW) influences on significant temperature perturbations (10–20 K) within a course of one day detected by an Fe lidar from 35 to 51 km in the austral winter of 2011 at McMurdo (77.8°S, 166.7°E), Antarctica. Such large temperature perturbations are captured in the Modern Era Retrospective‐Analysis for Research and Applications (MERRA) data and correspond to various phases of eastward propagating PWs with periods of 1–5 days as revealed in MERRA. The strongest PW dominating the temperature perturbations has a period of 4–5 days with wavenumber −1. A 2−day wave with wavenumber −2 and a 1.25−day wave with wavenumber −3 also have significant influences. We find that these eastward propagating PWs are highly confined to winter high latitudes, likely because negative refractive indices equatorward of ~45°S result in evanescent wave characteristics and prevent the PWs from propagating to lower latitudes. The Eliassen‐Palm flux divergence and instability analyses suggest that barotropic/baroclinic instability at 50°S–60°S induced by the stratospheric polar night jet and/or the “double‐jet” structure is the most likely wave source. Such instability in the region poleward of 70°S is a complementary source for the 4−day wave, where we find that the heat flux of the 4−day wave is large and transported from ~70°S toward the pole above 40 km. This transport direction is likely linked to the meridional gradient of background temperature. The migrating diurnal tide near 78°S in the upper stratosphere is discernable, but significantly smaller than that of the dominant 4−day wave.