云南初夏干湿演变特征和基于CMIP6模式模拟的预估分析

使用1961—2020年的观测数据和2021—2080年的模式预估数据,首先分析了云南初夏干燥度指数（aridity index,AI）的演变特征和影响因子相对贡献,然后采用国际耦合模式比较计划第六阶段（CMIP6）中的20个全球模式,对SSP1-2.6、SSP2-4.5以及SSP5-8.5情景下云南初夏未来干湿变化进行了预估研究。结果表明：(1) 1961—2020年云南初夏气候整体湿润,但为变干燥的趋势,有明显的年代际变化特征,1960s、1970s以及2000s气候相对湿润,其余年代相对干燥,2000s（2010s）为1961年以来最湿润（干燥）的10年。(2) 2021—2080年在3种排放情景下,云南初夏气候较1995—2014年均为变干燥的趋势,SSP1-2.6、SSP2-4.5以及SSP5-8.5情景下,AI分别减少13.9%、17.9%以及24.9%,西南部将可能是湿润度降幅最大值中心。(3) 1961—2020年,降水对云南初夏气候干湿变化的贡献大于潜在蒸散量;而2021—2080年,潜在蒸散量对气候变干燥的贡献大于降水量,且随排放情景的增高和时间推移,其贡献将逐渐增大。

Dry-wet climate evolution feature and projection of future changes based on CMIP6 models in early summer over Yunnan province,China

The dry/wet climate change in early summer has an important impact on the industrial and ecological environment in Yunnan province. In this article, the evolution characteristics of aridity index (AI) were analyzed from 1961 to 2020 using observation data, and the probable trend in 2021-2080 was projected by using 20 CMIP6 models under SSP1-2.6, SSP2-4.5 and SSP5-8.5. The AI in early summer of Yunnan province showed a decreasing trend from 1961 to 2020, and it had obvious inter-decadal change characteristics, the climate of 1960s, 1970s and 2000s was humid, and the rest period was dry, 2000s (2010s) was the wettest (driest) decade since 1961. Under three SSPs from 2021 to 2080, the climate in early summer of Yunnan will be drier than the average of 1995-2014. The regional average AI over Yunnan would decrease by 13.9%, 17.9%, and 24.9% under SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. Southwestern Yunnan will be the center of the largest decrease for wetness. The main influencing factor of climate drying is precipitation in 1961-2020, but it will be potential evapotranspiration in 2021-2080, which would increase gradually with time and the increase of emission scenario.