P2     Application of Background Error Covariance Option 3 in CWB        WRFDA

Chen, Mei-Hsin, Chin-Tzu Fong, Central Weather Bureau, Taiwan and Yong-Run Guo, NCAR, USA.

This study reviewed the characteristics of background error covariance option 3 (CV3 BE) in WRFDA (Weather Research and Forecasting model data assimilation system), and its applications in CWB (Central Weather Bureau). CWB has used WRFDA with CV3 BE as its three-dimensional variational data assimilation analysis system for more than two years. The CV3 BE has been tuned in CWB WRFDA to adjust the forecast error distribution. In this year, outer-loops were implemented into the operational system. This study explains the benefits of using outer-loops, especially for typhoon cases. The future work on CV3 BE in CWB WRFDA will be mentioned in the end.