Gravity Wave Parameter Estimation in WACCM and DART

The Whole Atmosphere Community Climate Model (WACCM) is an extensive numerical model, encompassing the altitude range from the Earth's surface to the thermosphere. Despite its comprehensiveness, WACCM exhibits biases in the mesospheric winds. One possible explanation for these biases lies in the uncertainty associated with the parameterization of gravity waves (GWs). To address this issue, this study aims to estimate the uncertain parameters in the WACCM GW parameterization based on observations and data assimilation. We present initial results based on an Observing System Simulation Experiment (OSSE) to estimate the GW parameter in WACCM using the Data Assimilation Research Testbed (DART). We use front source GW parameters as an attempt and assimilate simulated observation data to WACCM to update parameter value in the DART assimilation cycle to obtain optimal parameter. The development of this algorithm can help fine-tune parameters in WACCM, ultimately improving simulations of GW. This research is not only for the purpose of revising the WACCM model, but also for technical research on parameter estimation of the model using the assimilation method. In OSSE, the results of parameters converge quickly. According to the analysis, this may be caused by a too small correlation of this parameter with temperature observations in the mesosphere.