Descent from the polar mesosphere and anomalously high stratopause observed in 8 years of water vapor and temperature satellite observations by the Odin Sub‐Millimeter Radiometer

Abstract

Using newly analyzed mesospheric water vapor and temperature observations from the Sub‐Millimeter 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 midwinter 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 75 km, and its slower descent to prewarming level (near 1 hPa) over 1.5–2 months. These three winters stand out in the current record of Odin/Sub‐Millimeter Radiometer observations started in July 2001.