In this paper,the solar radiation flux and the daily,total monthly and total annual solar radiations at 20 meteorological stations during the period of 1971-2000 are simulated using the observed data of solar radiation at Yinchuan and Guyuan meteorological stations in Ningxia Hui Autonomous Region in 5 years.The results show that the simulated values of solar radiation at Yinchuan Meteorological Station were higher than the observed ones but lower than the observed ones at Guyuan Meteorological Station.The simulated results of solar radiation fluxes at Yinchuan and Guyuan stations were tested with the methods of bias error,mean absolute bias error,root mean square error and mean absolute error.It is found that the root mean square error was slightly higher,the mean absolute bias error was lower than 13% and 17% at Yinchuan and Guyuan stations respectively.Regionally,the simulated and observed values of total monthly solar radiation are in a decrease trend at Yinchuan Station in the north where it is arid.There is an increase trend in March,April,May and June,a slight increase trend in July,and a decrease trend in other months at Guyuan Station in the south where it is rainy.The total observed annual solar radiation is in a slight increase trend,and the accumulated simulated value is stable.The total annual solar radiation is significantly increased at most stations but significantly decreased at a few stations.

Based on coefficients of spring wheat Yongliang 4 in Ningxia,the CERES-Wheat model in DSSAT35 crop model was applied to simulate the resonse to climate change.The growth stage and potential yields were simulated on the same cultivar type under baseline years(1961-1990) and future climate scenarios of A2(CO2 releases about 1%) and B2(CO2 releases about 0.5%) scenarios in the Yellow River irrigation region of Ningxia for 59 grids(25 km×25 km each scale).According to average yield of 30 years under baseline year(1961-1990),simulation result of the future 100 years' yields under A2,B2 climate scenarios in three different periods,2011-2041,2041-2070,2071-2100 year,were compared with Baseline year.The result showed that average yield in baseline year was 6 234 kg/ha,decreases trend in yield presented under both A2 and B2 scenarios in the future,and was more obvious in A2 scenario.Decrease rate was 3%,8.6%,17.7% and 3.1%,6.9%,10.5% in three different periods under A2 and B2 scenario,respectively.Anthesis and maturity date and total evapotranspiration in season under three climate scenarios were simulated.The results showed that in three climate scenarios the growth length range was 24~25 d from anthesis to maturity(physiological).Under A2 and B2 scenarios,anthesis and maturity(physiological) date were earlier than under Baseline years.Average total evapotranspiration of 30 years in season was 446 mm under baseline the scenario and appeared increase trend under A2 scenario,but increment was a little.Under B2 scenario in the first two periods(2011-2040,2041-2070),average total evapotrans piration was about 444~445 mm almost no change comparing with baseline year,in the last period(2071-2100) average evapotranspiration of 30 years increased up to 450 mm,increment was only 4 mm comparied with Baseline in whole season.Simulation results of cumulative irrigation in season under Baseline,A2 abd B2 climate scenarios showed nearly no variation on average irrigation in any stage of the three scenarios.Under A2 and B2,simulation irrigation quantity decreased than under Baseline by 1～6 mm.

Under the conditions that insect pest and diseases were not considered,the CERES-Wheat model in DSSAT3.5 crop modeling was applied to predict potential yield of spring wheat in Ningxia.Through adjusting spring wheat cultivar coefficients of Yongliang No.4 on Yongning County and validating the model,cultivar coefficients were identified.Using these coefficients,growth performance and potential yields were simulated on the same cultivar for 15 years(1986～2000) in Pingluo County.The results showed that between simulation and observation there was a good approach for potential yields and flowering days,and a larger error for physiological maturity days.Under the future climate scenarios(A2 and B2 scenarios),in Huanghe irrigation area of Ningxia for 39 grids(25 km×25 km scale),potential yields were simulated for 90 years which were divided into three stages(2011～2040,2041～2070,2071～2100) and were compared with baseline climate scenario(1961～1990).The results showed that potential yields under both future climate scenarios(A2 and B2) would decrease compared with that under the baseline climate scenario by 3%,8% and 19% under three different stages of A2 climate scenario respectively,and by 3%,7% and 11% under three different stages of B2 climate scenario.The decrease rate under higher release of CO2 was larger than that under lower release.

Based on observation data of daily solar radiation of Yinchuan station during 1981-1985,along with linear relationship between observation values of solar radiation and extraterrestrial radiation,sunshine duration and daylength,the regional coefficient as was obtained,and sensitivity test was done to the values of bs,finally the best values of as=0.3,bs=0.5 was obtained to estimate regional solar radiation.In the light of the regional coefficients and calculation formula of solar radiation,the daily solar radiation in the year of 1986 and 1987 at Yinchuan station was estimated,and comparison was done between estimated values and observation data.Results show the correlation coefficient R2 was 0.94,which validated the reliability of regional coefficients.The daily solar radiation at Yongning station was estimated using the related formula of solar radiation and regional coefficients during 1989-2000,and compared with observation data of Yinchuan station.Results show that there were good linear relationship between them,and the minimum of R2 was 0.88 in twelve years.

对全区20个市、县1981-2000年小麦单产的年际变化进行初步分析得知,1987年引黄灌区的县、市小麦单产达到20年间的最低值;盐池小麦单产为中部干旱带的最大县,海原、同心、固原、西吉的小麦单产几乎是全区最低县;泾源县的小麦单产达固原地区的最大值。对1993年3县20年间小麦单产高产的气象条件分析,发现小麦生长期内,灌区两县降水量条件不满足,但对单产高产无影响;西吉县前期墒情好,小麦生长期内,降水条件各月虽有偏多、偏少的差异,总降水量正常,小麦高产的气象条件有利。