全球升温1.5℃和2.0℃情景下澜沧江流域极端降水的变化特征

澜沧江是我国为数不多的跨境河流,流域内多发暴雨、洪水灾害,因此定量、科学地评估澜沧江流域未来全球升温情景下极端降水的变化特征,能够为澜沧江-湄公河沿线国家共同管理流域水资源和抵御自然灾害提供一定的科学指导。文中基于部门间影响模式比较计划（ISI-MIP）下5个全球气候模式降水数据,通过偏差校正增强其在澜沧江流域极端降水的模拟能力,使用降水强度、日最大降水量和强降水量等9个指标评价未来全球升温1.5℃和2.0℃下澜沧江流域极端降水的变化情况,并对结果的不确定性和可信度进行研究,得出以下主要结论：随着全球温度的升高,澜沧江流域年降水和极端降水均呈现增大趋势,其中极强降水量（R99p）升幅最大,升温1.5℃和2.0℃下升幅分别为37%和75%;相对于基准期,全球升温2.0℃下各极端降水指数增幅明显大于升温1.5℃,前者升幅甚至超出后者一倍;未来全球升温情景下,澜沧江流域湿季会变得更湿润,而干季则会更干燥;澜沧江流域降水集中程度会增大,使得流域内洪涝灾害发生的风险增大;ISI-MIP气候模式对澜沧江流域未来极端降水模拟存在较大不确定性,升温2.0℃较升温1.5℃情景下不确定性更大,但相对于基准期,前者极端降水增大的可信度更高。

Variation of extreme precipitation in Lancang River basin under global warming of 1.5℃ and 2.0℃

Lancang River is one of the few cross-border rivers in China, and there are many torrential rains and flood disasters in the basin. Therefore, the scientific assessment of the changes of extreme precipitation in the Lancang River basin under the future global warming scenario can provide some scientific guidance for the countries along the Lancang-Mekong River to jointly manage the basin water resources and resist natural disasters. Based on the rainfall data of five global climate models under the Inter-Sectoral Impact Model Comparison Program (ISI-MIP), the simulation ability of extreme precipitation was enhanced in the Lancang River basin through bias correction. A total of 9 indicators, such as precipitation intensity, daily maximum precipitation, and heavy precipitation, were used to evaluate the changes of extreme precipitation in the Lancang River basin under the global warming of 1.5℃ and 2.0℃ in the future, and the uncertainty and reliability of the results were also studied. The main conclusions are as follows. With the increase of global temperature, the annual precipitation and extreme precipitation in Lancang River basin show an increasing trend, in which extremely strong precipitation increase the most by 37% and 75%, respectively under the global warming of 1.5℃ and 2.0℃. Compared with the historical benchmark period, the increase of extreme precipitation index at 2.0℃ is obviously larger than that at 1.5℃, and the amplification of the former is almost twice that of the later. In the future global warming scenarios, the wet season in the Lancang River basin will become more humid, while the dry season drier. The concentration of precipitation in the Lancang River basin will increase, which increases the risk of flood disasters in the wet season. The future extreme precipitation simulation from the ISI-MIP climate models has great uncertainty over the Lancang River basin, which is greater under 2.0℃ global warming than that under 1.5℃, but the reliability of increasing extreme precipitation relative to the historical benchmark period for the former is higher.