Abstract: The oases in northwest China have experienced the rapid urbanization and agricultural reclamation during the last decades. In order to investigate the effects of these land use/cover changes on regional environment,the Weather Research and Forecast (WRF) model was used in researching the Hami Oasis in this study.Two 1-month simulations were conducted separately in July with different land use/cover datasets derived from the satellite images of 2000 and 2015.Firstly,we not only used the data from the observation stations to validate the model accuracy,but also used the remote sensing retrieval data to validate the land surface temperature.The values of 2 m height air temperature were validated through the bias between the observed values and the outputs of WRF model,and the root mean square error (RMSE) between the observed values and the model outputs,the correlation coefficient (R) between the observed values and the model outputs,and the average Bias,and RMSE and R between the observed values and the model outputs were 0.4,1.7 and 84% respectively.The average bias,RMSE and 2 m height relative humidity was 1.6,5.8 and 81% respectively.The correlation coefficient of land surface temperature between remote sensing retrieval value and the model out was 87%.These results showed that our model was very reliable.Secondly,this paper investigated the 2 m height temperature,2 m height relative humidity and land surface temperature in 2000 and 2015 respectively.Comparison between the model results showed that 2 m height temperature was increased by 1.2 ℃ and the 2 m height relative humidity by 2% from 2000 to 2015 in the whole region.The 2 m height temperature was increased by 2.5-3 ℃ and the land surface temperature by 6-7.5 ℃,but the 2 m height relative humidity was decreased by 4%-8% when the land use/cover transformed from oasis to urban area.On the contrast,the 2 m height air temperature was increased by 1-2 ℃ and the land surface temperature by 3-6 ℃,but the 2 m height relative humidity was decreased by 0-4% when the desert was replaced by urban area.In addition,the 2 m height temperature was decreased by 1.5-4 ℃ and land surface temperature by 0-7.5 ℃,but the 2 m height relative humidity was increased by 4%-16% when the land use/cover transformed from desert to oasis.As a conclusion,the urban sprawl intensified the effect of the urban heat and dry island,while the oasis expansion made the oasis cool and the wet island more obvious.

Key words: WRF, LUCC, 2 m height air temperature, 2 m height relativity humidity, surface temperature, Hami oasis