Abstract:

   For the first time, the Advanced Regional Prediction Systems model is used to simulate tropospheric-stratospheric conditions over Antarctica. With a 6-km horizontal resolution, a 15 July 2008 simulation reveals orographic gravity waves generated by persistent, near-surface flow down the slopes of the Antarctic Peninsula and the western coast of the Ross Sea. These waves propagate well into the upper stratosphere and the associated vertical wind and temperature perturbations can exceed 10 m s-1 and 10 K, respectively. At the 15-25 km altitude levels where the temperature is well below 190 K, bands of pure ice polar stratospheric clouds (PSCs) collocate with wave-induced cold anomalies and bear likeness to the optically thick PSCs observed from spaceborne lidar backscatter. These PSCs are coupled to an underlying tropospheric ice cloud. When the model's horizotal resolution is decreased to 12 km, the simulation produces much weaker OGW amplitude and less PSCs.

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