Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/126060
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Type: Journal article
Title: Trends and variability in vertical winds in the Southern Hemisphere Summer Polar Mesosphere and Lower Thermosphere
Author: Vincent, R.A.
Kovalam, S.
Murphy, D.J.
Reid, I.M.
Younger, J.P.
Citation: Journal of Geophysical Research: Atmospheres, 2019; 124(21):11070-11085
Publisher: Wiley; American Geophysical Union
Issue Date: 2019
ISSN: 2169-897X
2169-8996
Statement of
Responsibility: 
R.A. Vincent, S. Kovalam, D.J. Murphy, I.M. Reid, and J.P. Younger
Abstract: Direct measurement of mean vertical velocities in the mesosphere‐lower thermosphere (60–110 km) is not possible due to their small values. Here we derive vertical velocities using the divergence of the mean meridional wind over the Antarctic summer pole using MF radar wind measurements made at Davis Station (69°S, 78°E) between 1994 and 2018. Estimates of vertical velocity are restricted to a 21‐day period centered just after solstice when the equatorward wind reaches its maximum value of about 15 m s⁻¹ at heights near 90 km. The Medium Frequency (MF) radar winds are calibrated against colocated meteor wind radar observations. Neutral densities required for the vertical wind calculations are obtained from zonally averaged temperature measurements obtained by the MLS instrument aboard the AURA satellite. The estimated vertical velocities have peak values varying between 2 and 6 cm s⁻¹ with significant interannual variability. While the peak values do not show significant long‐term change, there is a long‐term decrease in the mean height of maximum winds of about 0.6 km per decade that is statistically significant. The interannual variability is linked to the date of transition in the stratospheric zonal circulation from winter eastward to summer westward flow. Meridional and vertical velocities are smaller and peak at lower altitudes during early transitions (20–30 days prior to solstice) than is the case for late transitions that occur at solstice or later.
Keywords: Mesosphere‐thermosphere; winds and temperature; vertical velocity; middle atmosphere coupling
Rights: ©2019. American Geophysical Union. All Rights Reserved.
RMID: 1000005255
DOI: 10.1029/2019JD030735
Appears in Collections:Physics publications

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