Comparison of TIMED/SABER Data with the NOGAPS forecast system during stratospheric warmings and mesospheric coolings

The Sounding of the Atmosphere with Broadband Emission Radiometry (SABER) experiment on the TIMED satellite provides comprehensive temperature data from the lower stratosphere to the lower thermosphere. These data are proving invaluable to study the vertical coupling between the stratosphere, mesosphere and lower thermosphere. Of particular interest is the response of the entire atmosphere to stratospheric warming events. We have studied three such events: February 2002 in the Northern Hemisphere; August, 2002 in the Southern Hemisphere; and Jan/Feb 2003 in the Northern Hemisphere. The SABER temperatures show a clear signature of mesospheric coolings in concert with stratospheric warmings. Mesospheric temperatures between 0.7 mb and 0.01 mb show a clear and significant anticorrelation with stratospheric temperatures with no phase lag or lead. For pressures < 0.01 mb, this anticorrelation breaks down, suggesting that mesospheric cooling events do not extend to suggestion ofaltitudes higher than 80 km. Intriguingly, at the highest altitudes in August 2002 there is a region of positive correlation with the stratosphere. Such a lower thermospheric response has been predicted by theory, but never documented by a global dataset. We have compared the August 2002 observations with hindcasts using the Navy Operational Global Atmospheric Prediction System (NOGAPS) which has been recently extended up to 85-100 km. Good agreement is seen between SABER and NOGAPS over a 5-10 day period, although the model appears to underestimate the depth of the mesospheric cooling. This likely suggests the need for greater gravity wave drag in the model. We will review this model-data comparison and attempt to generalize our results other dynamically disturbed periods.