不同物理约束方案下西北地区夏季降水的未来预估对比OA北大核心CSTPCD

Northwest China experiences a scarcity of annual precipitation,characterized as a typical inland arid and semi-arid region.In recent years,various evidence has indicated an increasing trend in precipitation in this region.Understanding how precipitation will change in Northwest China under future warming has become a topic of widespread concern in the academic and social spheres in China.Based on two physically constrained(preferred)methods,namely,the emergent constraint and the Pareto-optimal ensemble scheme,two influential physical factors affecting summer precipitation in Northwest China were selected:tropical Indian Ocean sea surface temperature(SST)and the East Asian subtropical 200 hPa zonal wind.Different constraint schemes were applied to the summer precipitation projections from 25 CMIP6 models.The results show that,relative to the period 1995-2014,the ensemble mean of CMIP6 models projects a 23%increase in average summer precipitation in Northwest China by the end of the 21st century.The unconstrained estimation range is from-8.4%to 61.7%.After constraining with tropical Indian Ocean SST(East Asian subtropical 200 hPa zonal wind),the projected increase reaches 24%(19%),and the uncertainty range narrows to-8.4%to 52%(-9%to 45%),reducing uncertainties by 15%(21%).Further utilization of the three-variable Pareto-optimal ensemble scheme,including historical summer precipitation in Northwest China,tropical Indian Ocean SST,and East Asian subtropical 200 hPa zonal wind,indicates a 28%increase in average summer precipitation in Northwest China by the end of the 21st century,with a narrowed uncertainty range of 8%to 44%,representing a nearly 39%reduction in uncertainty.The Pareto-optimal ensemble suggests that the regions experiencing increased precipitation are concentrated in the central and western parts of Northwest China,with the maximum precipitation increase exceeding 60%.