亚非地区近百年干旱时空变化特征

Temporal and Spatial Variation Characteristics of Drought in Asia and Africa Regions from 1901 to 2010

利用1901—2010年帕默尔指数(PDSI)和1981—2010年CMAP降水、NCAR 700 h Pa位势高度等格点资料,分析亚非干旱、半干旱带中北非、中东、中亚西部、中亚东部至中国西北地区西部及中国西北地区东部、华北和东北等7个区域PDSI的时空演变特征。结果表明:北非至中东地区大部,前20 a(1901—1920年)PDSI为-1~2,干旱较轻或相对不旱;1920年代以后PDSI为-4^-2,干旱较重。与其他地区不同的是,中亚东部至中国西北地区西部1980年代以后PDSI>0,这与该区同时期700 h Pa位势高度下降及夏季降水量增加有关。PDSI≤-2的干旱期,有从北非地区到中国东北地区逐区向东扩展的趋势,后延推移间隔约为24~31 a,这对干旱气候预测有一定的参考意义。

Based on the Palmer drought severity index(PDSI)data during 1901-2010,monthly precipitation from CMAP dataset and 700 hPa geopotential height field from NACR during 1981-2010,the temporal and spatial change characteristics of PDSI in seven arid and semi-arid regions of Africa and Asia area(Northern Africa,Middle East,Western Asia,Eastern Asia to west of Northwest China,east of Northwest China,North China and Northeast China)were analyzed.The results showed that most of decadal average PDSI was negative in A to G regions of Africa and Asia during 1901-2010,which was basically in the state of drought.However,the values of PDSI ranged from-1 to 2 during 1901-1920,which showed that drought was light,while PDSI was-4 to-2 from 1921 to 2010,drought was severe.Unlike other regions,PDSI was more than 0 in the west of Northwest China(D region)to east of Central Asia during 1981-2010,which was closely related to decrease of 700 hPa geopotential height and increase of summer precipitation at the same period.The drought with PDSI below-2 had a trend of spreading gradually eastwards from A to G region of Africa and Asia,and the backward intervals were about 24-31 years,which had a certain reference significance for drought climate prediction.