P6.8
Systematic Model-Data Differences and Optimization of Forced Modes of the MLT dynamics: Zonal Mean Flow and Migrating Diurnal Tide
Valery Yudin, NCAR, Boulder, CO; and F. Sassi
This paper examines feasibility and limitations to use the satellite-based monthly horizontal winds and temperatures to evaluate and constrain the balanced and forced components of model predictions in the MLT region. The motivation of this study is to formulate the family of statistical inverse estimation schemes that can provide constraints on the “missing” momentum tendencies. Under the assumption that the diagnosed momentum deficit can be associated with misspecification of stochastic effects of gravity waves (GW), appropriate adjustments of uncertain parameters in the GW parameterizations (GWP) can be envisioned to suppress the persistent model-data differences. Given the variability in responses of simulations to variations of parameters in the GWP and the sampling and retrieval errors in the satellite data, we discuss uncertainties of the derived constraints. In practice, the evaluation of model predictions starts from the analysis of persistent model-data differences in the zonal mean states and migrating tides. These dynamical components can be more or less confidently deduced from research satellite data collected over the long-term time windows. We discuss the formulation of inverse schemes for optimization of these modes. We also highlight the importance of additional constraints related to reproduction of observed GW-rms by parameterizations and strengths of effective eddy mixing (GW energy deposition). A brief overview of recent efforts to constrain GWP in the stratosphere and MLT by the NWP analyses and research satellite data is provided in the context of formulated statistical estimation schemes.
Poster Session 6, Gravity Wave Observations, Modeling and Parameterization
Thursday, 23 August 2007, 3:30 PM-5:30 PM, Holladay
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