The development of the Arctic polar vortex in fall 2004: analyses of Aura Microwave Limb Sounder observations

The development of the stratospheric polar vortex in fall is critical to many aspects of its evolution later in winter, but has received little attention. Previously, data with which to study this evolution have been sparse, especially in the upper stratosphere and near the stratopause. The recently launched Aura Microwave Limb Sounder (MLS) instrument provides many new measurements useful for studying polar vortex development. In this poster, we show initial results from MLS detailing the evolution of the developing vortex (the "protovortex") in the northern hemisphere fall of 2004. Observations of carbon monoxide and water vapor are used to examine the development of the vortex in the upper stratosphere and across the stratopause, and descent of mesospheric air into the protovortex; MLS observations of temperature and geopotential height can also help define the structure and evolution of the vortex in the upper stratosphere and lower mesosphere. Nitrous oxide and water vapor measurements are used to study vortex development in the middle to lower stratosphere.