On Recent Interannual Variability of the Arctic Winter Mesosphere: Implications for Tracer Descent
NAVAL RESEARCH LAB WASHINGTON DC
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Observations from the Sounding of the Atmosphere with Broadband Emission Radiometry SABER experiment on the NASAThermosphere Ionosphere Mesosphere Energetics and Dynamics TIMED satellite show an unusual vertical displacement of the winter Arctic stratopause in 2006 with zonal mean temperatures at 0.01 hPa 78 km exceeding 250 K. By contrast, at the conventional stratopause location near 0.7 hPa 50 km, temperatures were unusually cold. Simulations with the NOGAPS-ALPHA model suggest that these are coupled to an unusually warm and disturbed lower stratosphere that filtered out many of the gravity waves that normally break at and above 50 km. The model also shows that downward transport in the 2006 Arctic vortex was enhanced relative to 2005. These results might explain observations of enhanced upper atmospheric NO descending to the upper stratosphere in 2006 and highlights the importance of gravity waves in modulating the coupling of the upper atmosphere with the stratosphere.
- Atmospheric Physics