Comparative Analysis On The Simulated Regional Climate In China By RegCM3.0and RegCM4.0

Compare to the global general circulation model (GCM), high resolution regional climate model can not only describe physical processes and their parameterization better, but also get more detailed imformation in smaller scale. Just for such a reason, regional climate model can describe the regional and local climate better than GCM. Climate simulation over China given by GCMs always shows evident bias, because of the complex terrain and changeable climate. Sothe application of regional climate model in China is very important. RegCM is one of most widely used regional climate models. Its latest version RegCM4.0with a lot of improvement in physical process have been issueded in June.2010. Testing its suitable in our country and comparing it to RegCM3is necessary due to no use in China.In this paper, by using RegCM3and RegCM4of NCAR and U.S. National Centers for Environmental Prediction renalysis II and weekly sea temperature of NOAA, we simulated to four typical raininess year(1998,2003,2007,2010) and the summer near thities years from1982to2010. The conclusion from the simulation have been compared to the national observation precipitation and temperature data from743stations throughing diagnosis and statistical test.At the same time, we preliminary analyze the effect of simulations on land surface processes to atmospheric variables. The main conclusions are as follows:(1) From the years on average precipitation, RegCM3, RegCM4-BATS, RegCM4-CLM3.5all can basically simulate precipitation spatial patterns and primary rainbands in China, but there is a certain deviation between simulated rainbands and oberservation rainbands, the overall southerly. Comparatively speaking, the RegCM4-BATS, simulat rain belts with observations closer, especially with the simulation of heavy precipitation belts along the southeast coast, the other two programs simulate smaller scope of the heavy precipitation area and the value is lower.(2) National average summer precipitation values simulated by the three projects are smaller than the oberserved value. Seen from the view of the national area, the three projects simulate precipitation less than normal. Relatively speaking, the precipitation values simulated by RegCM4-BATS which is closer to the observed value and have a better precipitation distribution patterns is larger than the other two projects. The three projects, especially RegCM3and RegCM4-CLM3.5, simulate too few in the humid area, which is more prominent in the south of the Yangtze Rive and the area near the Huai River.In the semi-arid and semi-humid area, especially in the northeast and eastern plateau, they all simulate long bias. (3) The three projects of RegCM3, RegCM4-BATS, RegCM4-CLM3.5are all able to simulate the temperature of the high value areas which are located along the southeast coast and the desert in Xinjiang. RegCM3simulate the low value temperature in the area of southeast coast, the other two projects simulate the same value to the oberservation temperature in the area of southeast coast which have high value of temperature, but the location is northerly. The three projects simulate the existence of the cooling zone of the Qinghai-Tibet Plateau.The simulated cold area is large than the observation and the cold center temperature is lower than the observation, below5℃. In addition, due to topographic effects, the simulated temperature is low.(4) the average summer temperature between1982-2010simulated by the three projects is less than the observed values. Seen from the view of the national area, the simulation of the three are cold bias.The summer average temperature simulated by RegCM3is lower more across our country. Relatively speaking, the average summer temperature distribution pattern and the value which simulate by RegCM4-BATS is best. The temperature interannual variability of the trend simulated by RegCM4-BAT is more consistent with the observations. The two kinds of programs of RegCM4is better to compared RegCM3.0on the long-term trend in the average summer temperature simulation(5) There is a good positive correlation between the simulated sensible heat flux and temperature.Whether it is a typical year or the average sensible heat of29years, in the south of the Yangtze Rive and the South China RegCM4-CLM3.5simulate larger.Contrast to temperature distribution shows that RegCM4-CLM3.5simulate high temperature at these areas.we can see that the accuracy of the land surface process simulation have a significant impact on simulation of atmospheric processes, and vice versa. The national summer soil moisture distribution simulated by the three projects is more realistic.There is also a good positive correlation between soil moisture and precipitation. although the soil moisture is not the only factor to affect the precipitation, the magnitude and distribution of soil moisture has a great influence on the precipitation simulation. The soil moisture simulated by RegCM4-BATS is relatively accurate, so it is best to simulate precipitation..