Implementation of Windsat Data From NPOESS into 3DVAR for CANSAC Real-Time MM5 Forecasting

The Climate, Ecosystem and Fire Application (CEFA) at the Desert Research Institute (DRI) provides the California and Nevada Smoke and Air Committee (CANSAC) with two times daily (0000 and 1200 UTC) real-time meteorological forecast by use of the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (NCAR) Mesoscale Model (MM5) initialized by National Center for Environmental Prediction (NCEP) ETA model. Windsat data from National Polar-orbiting Operational Environmental Satellite System (NPOESS) are assimilated into MM5 by use of Three-Dimensional VARiational data assimilation system (3DVAR) to improve and evaluate the accuracy of meteorological mesoscale foresting.

In this study, the 3DVAR code is modified to use Windsat Environmental Data Records of wind speed and direction to be input into MM5 model; and the effect of 3DVAR Windsat data is investigated by use of MM5 model outputs with and without (free forecast) the data. Impact of 3DVAR assimilation into different model domain resolutions is analyzed by different approaches such as applying into model coarser domain only (low resolution) and into all three domains (incorporating high resolution). Results presented from an initial real-time MM5-based application of 3DVAR are compared with the corresponding free run weather forecast in a 48-72 h assimilation period to explore the benefits of conducting the assimilation of the Windsat data in a cycle framework. It is expected that the 3DVAR system in a cycling mode can improve the model analysis and weather prediction with the use of local meteorological observations and Windsat data.