基于CMIP6的气候变化下汉江流域气象干旱特征研究

CMIP6-based meteorological drought characteristic study under climate change in the Hanjiang River Basin

为明晰气候变化下汉江流域气象干旱的演变特征,选取CMIP6中10个气候模式,考虑每个气候模式历史情景与4种共享社会经济路径(SSPs)情景,基于标准化降水蒸散指数分析了汉江流域气象干旱特征的变化规律。结果表明:未来汉江流域年降水量与潜在蒸散量最大差值逐渐增大,增长速率为0.92~2.40 mm/a,最小差值在不同SSPs情景下变化趋势不同,在SSP1-2.6和SSP3-7.0情景下逐渐缩小,而在SSP2-4.5和SSP5-8.5情景下持续增大;历史情景下流域干旱累计时长表现为东西短、中部长的特点,而未来流域中下游干旱累计时长减小,上游略有增大,且干旱在年内发生时间相对提前;未来低重现期干旱烈度不会发生明显变化,但极端干旱烈度将显著上升,100年一遇干旱烈度增长幅度为7.1%~25.6%。

To clarify the impact of climate change on meteorological drought characteristics in the Hanjiang River Basin,10 climate models of CMIP6 were selected,considering historical scenario and four shared socioeconomic pathways(SSPs).The standardized precipitation evapotranspiration index was calculated and variation of meteorological drought characteristics was studied.The results indicate that the maximum difference between the annual precipitation and potential evapotranspiration in the Hanjiang River Basin in the future gradually increases,with a growth rate ranging from 0.92 to 2.40 mm/a,while the minimum difference has different trends under different SSPs,with a relative decrease in SSP1-2.6 and SSP3-7.0 scenarios and a continuous increase in SSP2-4.5 and SSP5-8.5 scenarios.In the historical scenario,the cumulative drought duration in a year is shorter in the east and west,but longer in the middle of the basin.In SSPs scenarios,the cumulative drought duration in a year is expected to decrease in the middle and lower reaches,but increase slightly in the upper reaches,and droughts are likely to occur earlier in a year.In the future,the intensity of drought with short return periods will not change significantly,but the intensity of extreme drought will increase substantially,with a growth rate of 7.1%to 25.6%for drought with a return period of 100 years.