PRECIS模式对新疆降水变化情景的模拟分析

Analysis on the scenarios of future precipitation change in Xinjiang by PRECIS

利用ERA40再分析数据作为边界条件驱动PRECIS(Providing Regional Climates for Impacts Studies)模式,对新疆年季降水量进行评估研究。结果表明,PRECIS能够模拟出西北、西南到东南逐渐减少的空间格局分布特征,还可模拟出整体的新疆年降水、冬季降水和夏季降水均有增加的时间变化趋势。相对于气候基准时段,A2与B2情景下(2020s、2050s、2080s)年降水、冬季降水和夏季降水变率均有很大增加,随年代际的变化其降水变率的增加幅度变化也很大。这与新疆暖湿转型结论相互印证。

Two 30-year time-slice simulations（present-day climate（1961-1990） and one of the IPCC greenhouse gases emission future scenario（A2 and B2 IPCC-SRES with precipitation data）） for 2071-2100 have been performed by using a regional climate model nested model. The PRECIS（Providing Regional Climates for Impacts Studies） model domain is centered in the Xinjiang region,considered one of the most sensitive areas regarding to global warming and future precipitation extreme conditions. The generated precipitation by the PRECIS for Xinjiang from 1961-2014 is compared with observed data. Taking the period of 1961 to 1990 as a base,the changes of precipitation in 2020 s,2050s and 2080 s were evaluated. Results show that the PRECIS could well reproduce historical spatial distribution of precipitation with a decrease from northwest and southwest toward southeast in Xinjiang. An increase in precipitation is expected under both SRES A2 and B2,but summer precipitation increases more than winter precipitation does. Both climate change scenarios generate a similar pattern of precipitation distribution in space. The extremes of the annual and summer precipitation exist in Ruoqiang areas,while the extremes of the winter precipitation take place in Kashi,Changji and Yili. A decadal increasing trend of precipitation is predicted in both SRES A2 and B2. Annual and summer precipitation increases significantly on comparison with the baseline climate period（1961-1990）,with the highest of 78. 6 percent during 2080 s under the scenario of B2. The Scenario B2 generates more annual,summer and winter precipitation than the Scenarios A2 does during simulation period by the 2100 except that the Scenario A2 generates more summer precipitation than the Scenarios B2 does during 2080 s.