中国南北过渡带干旱时空变化

为识别中国南北过渡带的干旱状况,利用研究区内1960-2015年32个气象站逐月降水量和月平均气温等资料,计算每个站点的逐月综合气象干旱指数CI,并利用累积距平法等分析中国南北过渡带干旱变化情况。结果表明:就时间变化而言,干旱强度、干旱历时以及不同等级的干旱发生频率随时间均呈上升趋势,并且,轻旱在所有等级干旱中占比最重,为55.6%;就季节变化而言,干旱的发生具有季节性规律,春旱的强度最大,且历时较长,夏旱最易发生,秋旱的发生频率总体呈现出先增大后减小的趋势,在20世纪90年代达到最大值,冬旱的历时值最短;就空间变化而言,研究区内北部相对干旱,南部相对湿润,武都地区和研究区内的河南地区最为干旱,甘肃南部反而是整个研究区最湿润的地区。

Spatiotemporal changes of drought in the North2South transitional zone of China

In or der t o ident ify the occurr ence of dro ug ht in the North2So uth t ransitio nal zo ne ( Qinling2Dabashan) of China, t his paper used monthly precipitat ion and mean temperature of 32 meteor olog ical stations f rom 1960 to 2015 to calculate the monthly dr ought in the study ar ea. T he met eo ro lo gical dro ug ht index CI and the cumulat ive anomaly method based on the principle of met eo ro lo gical dr ought classif ication w ere used to analyze the dro ug ht chang es in the No rth2South tr ansitional zo ne of China. The r esults show ed that the droug ht intensity , dur atio n and frequency of different levels o f dro ug ht incr eased wit h time, and the lig ht drought accounted fo r the most in all lev els of dro ug ht, w hich w as 551 6% . The occurrence o f dr ought had a seasonal pat2 ter n. The intensity o f spring dro ug ht w as t he lar gest and the dur ation was lo ng . T he summer dro ug ht w as the most likely to oc2 cur. The frequency of autumn dro ug ht generally increased first and then decr eased, reaching max imum in t he 1990s. The dur a2 tion of w inter dro ug ht was relativ ely short compar ed to ot her seasons. In terms of spatia l change, the northern part o f t he study area was r elativ ely dr y, and the so ut h w as relativ ely humid, the Wudu area and the Henan reg ion w as the airdest, w her eas the so uther n part of Gansu w as the wettest reg io n in the entire study area.