92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Monday, 23 January 2012
Examination of Sensitivity of WRF Precipitation Over Japan to Physical Parameterizations and Horizontal Resolution
Hall E (New Orleans Convention Center )
Kohei Ikeda, Japan Agency for Marine-Earth Science and Technology, Yokohama, Kanagawa, Japan; and K. Yamaji and M. Takigawa

Long-range transport of air pollutants associated with recent increase in air pollutant emissions in the East Asia has been studied by global chemical transport models and regional air quality models. Accurate representation of meteorological processes is important to reproduce the transboundary transport of air pollutants among East Asian countries. We investigate the sensitivity of model reproduced precipitation to microphysical, cumulus convection, and planetary boundary layer parameterizations. In this study, the Weather Research and Forecasting model (WRFV3.2.1) is used, and three microphysical (MP) and cumulus convection (CU) and planetary boundary layer (PBL) schemes are combined in the sensitivity experiments. Sensitivity to horizontal resolution (80 and 20 km) is also examined by using 2-way nested domain with high resolution over Japan. Model simulations are performed over East Asia area for six months from January 2003 with nudging to NCEP reanalysis data. Model precipitation on the land and the sea around Japan (East China Sea, Japan Sea, and North West Pacific) is evaluated with weather station data of Japan Meteorological Agency (JMA) and satellite observation (GSMaP_MVK), respectively. Total amount of precipitation is more sensitive to MPs and CUs than to PBL schemes; difference of accumulated precipitation on the land with MPs and CUs is about 15 %. Averaged correlation coefficient of daily precipitation on the land is increased from 0.70 to 0.72 in the high resolution experiment. Both seasonal variation and amount of precipitation in the East China Sea are well reproduced in all experiments. In the North West Pacific, model precipitation is overestimated from January to March and underestimated from May to June. The WRF precipitation in the Japan Sea is considerably overestimated in the winter season (January to March), but further investigation of this reason is needed since the satellite data may underestimate the real precipitation.

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