| Summary: | Rayleigh lidars at Chatanika, Alaska (65N, 147W) and Kangerlussuaq, Greenland (67N, 51W) have measured the middle atmospheric density and temperature structure during the 2007-2008 winter. These lidars are part of the Arctic Observing Network during the fourth International Polar Year (IPY). The lidar observations have yielded measurements of mean profiles and the gravity wave activity in the upper stratosphere and mesosphere. TIMED-SABER satellite geopotential data are used to quantify the planetary wave activity in the middle atmosphere. UKMO and GEOS reanalysis data are used to describe the structure and evolution of the Arctic stratospheric-mesospheric vortex and Aleutian anticyclone. The lidars sampled both inside and outside the vortex and anticyclone characterizing the gravity wave activity under different synoptic regimes. A stratospheric warming occurred in late February 2008. A TIME-GCM simulation (with a model lower boundary specified by ECMWF) has been conducted for the November 2007-March 2008 period. This study allows us to characterize the planetary and gravity wave activity in the Arctic middle atmosphere during the IPY. These measurements and analyses will be compared with the TIME-GCM simulations to study the wave coupling between the middle and upper atmosphere and the expected response of the high latitude ionosphere to a stratospheric warming during the IPY.
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