87th AMS Annual Meeting

Tuesday, 16 January 2007: 1:30 PM
Extending NOGAPS-ALPHA into the lower thermosphere
210A (Henry B. Gonzalez Convention Center)
David E. Siskind, NRL, Washington, DC; and S. Eckermann, J. P. McCormack, L. Coy, and T. F. Hogan
For the last several years, we have been developing a middle atmosphere version of the spectral forecast model component of the Navy Operational Global Atmospheric Prediction System (NOGAPS), called NOGAPS-ALPHA (Advanced Level Physics High Altitude). This model prototype is an outgrowth of the operational NOGAPS and additionally includes a higher top altitude (95 km), upper-level meteorological initialization, higher vertical resolution (60-68 levels, L60-68), a hybrid sigma-pressure coordinate for the middle atmosphere, and additional physics packages (radiation, gravity wave drag). We have tested the performance of NOGAPS-ALPHA by hindcasting several well-observed global meteorological middle atmospheric disturbances (stratospheric warmings and mesospheric coolings). The include the unusual break up of the Southern Hemisphere stratospheric polar vortex and Ozone Hole during September 2002 and the minor warming precursor in August, for which mesospheric temperature data from the NASA/TIMED satellite are available.

Recently we have added a fully interactive prognostic ozone capability and have accounted for the effects of the mesospheric ozone diurnal variation on the radiative heating above 55 km. We have compared the resulting latitudinal variation of mesospheric temperature after a one week forecast and found it to be in excellent agreement with temperature data acquired from the TIMED satellite. Finally, we have extended NOGAPS-ALPHA into the lower thermosphere. This extension is enabled by the consideration of non-LTE cooling in CO2. This new module (the so-called Fomichev scheme) provides realistic cooling profiles and allows NOGAPS-ALPHA to successfully run with a model top above 110 km (an L74 model) We will show preliminary results from the L74 model, compare it with the older L68 version and evaluate the importance of non-LTE processes upon mesospheric and lower thermosphere temperature forecasts.

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