Tuesday, 13 January 2004
Prognostic ozone in NOGAPS
The current operational Navy Operational Global Atmospheric Prediction System (NOGAPS) forecast model uses a zonal mean ozone climatology to assess the radiative effects of ozone in the troposphere and stratosphere. Evaluation is underway of a new prognostic ozone field in a high-altitude (top at 0.005 mb) test version of NOGAPS. Initialized with offline assimilated data, the ozone is passively advected using the model's spectral transport scheme. Results are shown for a case study in September 2002, when anomalously large planetary-scale wave forcing in the upper troposphere caused the splitting of the Antarctic polar vortex. The NOGAPS ozone forecast compares favorably with satellite measurements from the Total Ozone Mapping Spectrometer (TOMS) and with offline assimilated ozone fields. The radiative effects of using the advected ozone rather than the ozone climatology are addressed by examining the forecast temperatures and offline radiation calculations. Plans for introducing parameterized ozone photochemistry into the model are discussed as well as plans for future assimilation of satellite ozone observations.