Abstract:

    Using newly analyzed mesospheric water vapor and temperature observations from the Sub-Millimetre Radiometer instrument aboard the Odin research satellite over the period 2001-2009, we present evidence for an anomalously strong descent of dry mesospheric air from the lower mesosphere into the upper stratosphere in the winters of 2004, 2006 and 2009. In the three cases, the descent follows the recovery of the upper stratospheric polar vortex from a major mid-winter stratospheric sudden warming. It is also accompanied by the rapid formation of an anomalously warm polar mesospheric layer, i.e. an elevated polar stratopause, near 75km, and its slower descent to pre-warming level (near 1 hPa) over 1.5-2 months. These three winters stand out in the current record of Odin/SMR observations started in July 2001.

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