中国未来极端气温变化的概率预估及其不确定性

本文基于第五次耦合模式比较计划的23个全球气候模式所提供的最高气温与最低气温在RCP4.5情景下的逐日格点资料,根据模式对5个极端气温指数的模拟能力,使用秩加权方法研究了中国未来极端气温变化的概率预估及其不确定性。结果表明,21世纪中期（2046—2065年）中国区域平均最高气温和平均最低气温的增加幅度相对于历史时期（1986—2005年）可能超过2.0℃（概率>66%),增加的大值区主要位于青藏高原南部。暖夜指数在中国大部分地区增加超过15%,西南和东南部沿海是增加的大值区,增幅超过20%。霜冻日数在全国范围内减少,减少的大值区位于青藏高原周围,减少日数超过了20 d。热浪指数在整个中国区域可能增加10 d以上,大值区位于西藏西南部,可达30 d。不确定性的结果表明,除热浪指数的可信度较低外,其余指数都有较高的可信度。到21世纪末期（2081—2100年),中国区域极端气温增加幅度超过前期,平均最高气温和平均最低气温很可能增加超过2.0℃（概率>90%),大值区除中国西部地区外,还扩展到了东北和青藏高原西南地区。中国大部分地区的暖夜指数增加超过15%,西南和南部沿海可能超过25%。大部分地区的霜冻日数减少20 d,青藏高原周围减少超过40 d。热浪指数在中国范围内增加20 d,青藏高原西南部增加40 d以上。除霜冻指数的信噪比略比21世纪中期大外,其余指数的信噪比与中期基本一致。

Probability projection and uncertainties of the temperature extreme indices change over China

Based on the daily maximum and minimum temperature from 23 climate models from Coupled Model Intercomparsion Project Phase 5 (CMIP5) under RCP4.5 scenario, five temperature extreme indices including average maximum temperature (TXAV), average minimum temperature (TNAV), heat wave duration index (HWDI), frost days (FD) and warm nights (TNF90) were calculated, and the probability projection of extreme temperature indices were analyzed after evaluating the performance of models in simulating the extreme indices. The results show that there has a high probability (more than 66% chance) of increasing by 2.0℃for TNAV and TXAV during mid of the 21st century. The increasing maximum regions are located over south of Tibetan Plateau region. TNF90 increases by 15% across the whole region, with the largest values over 20% in southwestern China and south coastal region. FD is projected to decrease with the largest negative magnitude over 20 d regions over the Tibetan Plateau. HWDI increase by 10 d occurs across the whole China region, with maximum value by 30 d located over southern Tibetan Plateau. The uncertainties results show that temperature indices change have large reliabilities except HWDI. For the end of the 21st century, the increase magnitude of indices is more remarkable than the former period, and both TNAV and TXAV have very high probabilities (larger than 90%) by 2.0℃. Increasing magnitudes of TNF90 over southwestern China and south coastal regions are larger than 25% while TNF90 in most regions decreases by 15%. FD decreases by 20 d in most regions and by 40 d around the Tibetan Plateau. HWDI increases by 20 d throughout the whole region, maxima increase region is located over southeastern of TP. The credibility is the same as that during the mid-21st century except FD.