Numerical simulation of climate changes over North China by the RegCM3 model

Using the high resolution regional climate model to estimate the regional future climate can help us to understand and assess the regional climate changes under the global warming. Based on the simulation conducted by National Climate Center with a high resolution regional climate model (RegCM3) at 25 km grid spacing nested within a global model of MIROC3. 2_hires, changes in precipitation, temperature and some related extreme climate events (frost days, growing season length, number of heavy precipitation days, simple daily intensity index and max 5-day precipitation amount) over North China under global warming are analyzed in this work. The simulation is carried out for the period of 1951-2100 following the observed greenhouse gases (1951-2000) and the IPCC SRES A1B emission scenario (2001-2100). The results suggest that the model is capable of simulating well the present (1981-2000) mean temperature, frost days and growing season length in both spatial distributions and values; but with some discrepancies in values of present mean precipitation, number of heavy precipitation days, simple daily intensity index and max 5-day precipitation amount. The RegCM3 model overestimates the values of present mean precipitation and related extreme indices. Compared to the driving global model, significant improvements have been shown by RegCM3 about the simulation of temperature, precipitation and extreme climate events. Increasing area averaged temperature and growing season length, together with decreasing frost days are simulated during the period of 2010-2100, at the same time an increasing trend of area averaged precipitation, number of heavy precipitation days, simple daily intensity index and max 5-day precipitation amount is indicated with the increasing greenhouse effect. In general, more obvious changes of temperature, precipitation and extreme climate events would occur in the late 21st century (2081-2100) compared to the middle 21st century (2041-2060) over North China.