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MMM SEMINAR NCAR

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Regional Climate Model Simulations Using MM5 and WRF Models

Dong-Kyou Lee

School of Earth and Environmental Sciences, Seoul National University

Seoul, Korea

A regional climate model (SNURCM) was configured by coupling the NCAR land surface model (LSM) and the MM5 model for longer-term simulations. The spectral nudging technique was implemented in the model to reduce systematic biases resulting from the incomplete treatment of downscaling problem in the classical lateral boundary condition. Initial soil moisture and temperature are obtained from an off-line run of the NCAR LSM for equilibrium of soil state using observed precipitation and large-scale forcing data. To evaluate the capability of the RCM, a 10-year summer monsoon climate and the 1998 extreme climate case over East Asia were simulated. The 10-year mean biases of ground temperature and precipitation in summer were cold (-1.3 C) and wet (0.8 mm/day), respectively, over East Asia. Inter-annual and intra-seasonal variability of surface climate variables also agreed with observation. In the simulation of the extreme flood case over East Asia, the major record-breaking flood event in central China was captured, and the simulated precipitation was found to be very sensitive to the cumulus parameterization schemes. Using the NCEP/NCAR reanalysis data there was no large difference in daily precipitation amount and intensity between one-month simulation and the 48-hour forecast simulation for the continuous heavy rainfall over southern Korea. For the 1998 flood in central China, the results of three-month simulations using the WRF model implemented with and without the spectral nudging technique are also discussed, and compared with that of the SNURCM results.

Thursday, 4 August 2005, 3:30 PM

Refreshments 3:15 PM

NCAR-Foothills Laboratory

3450 Mitchell Lane

Bldg 2, Rm1001