中文摘要：

在简要评述并对比了全球8大主要半永久性干旱半干旱区的情况后,也具体分析和讨论了中蒙干旱区的范围、面积、命名及其部分地区的降水分布细节及成因。主要结论如下：（1）全球主要有北非、澳大利亚及中蒙等8大干旱半干旱区。（2）中蒙干旱半干旱区主要覆盖中国北方大兴安岭？吕梁山一线以西、约36°N以北及蒙古国全境,总面积约5×106km2,是中国北方及蒙古国约1亿人口的家园。（3）中蒙干旱带呈中间干、南北两侧稍湿的格局。其最低雨量及年降水变率等堪与北非及澳大利亚等全球主要干旱区相比。该干旱区的主体及极端干旱区均在中国西北区。（4）中蒙干旱区的极端干旱区在南疆盆地东端,伴有托克逊等4个孤立的干中心,这是青藏高原大地形北缘的热力补偿下沉运动和东天山及阿尔金山等中地形背风坡焚风效应共同影响的结果;在高原东侧还有明显南伸的＂V＂形干谷,亦系高原东缘的热力补偿下沉所致。

英文摘要：

In this paper,after the simply review and intercomparison of the global eight major arid-and semiarid-areas have been done,also and the CMASA size,area,name and the some details of the precipitation distribution over part regions of CMASA have been calculated and analysed.The some main conclusions are as follows： There are eight major semi-permanent arid-and semiarid-areas totally in the world.They are the North Africa-,Midwest Australia-,Central Asia-,China-Mongolia and Midwest America arid-and semiarid-areas and so on,are mainly located in Africa,Asia and Oceanica.The CMASA is linked together and should be treated as a whole,not in partly.If taking simply the multi-year mean rainfall less than 200 mm and 200~500 mm as the criterions of arid-and semiarid-areas,respectively,then the CMASA covers both the entire Mongolia and north China bording on Daxinganli-Luliangshan a line to the east and the latitude of 36°N to the south,has the totally area of 5×106 km2,with the main body,making up 69% of its total area,and the extremely arid on China side.And it is the homeland of nearly one hundred million populations in China-Mongolia.The CMASA is dry in the middle,something wet on its south-and north-sides.On the China side,the southmost part of Shaanxi is quite humid,with the mean rainfall as much as more than 900 mm,but in the inland hyper arid region,Toksun,the east end of South Xinjiang Basin,is with the rainfall less than 7 mm only;on the Mongolia side,its central and northern part is with the rainfall more than 400 mm;south part,nearly 100 mm;its southwest corner,just 30 mm.The CMASA is a unique mid-latitude,inland dry zone in the Earth.There are four dry centers in isolation in the extremely dry region of the east end of South Xinjiang basin.That is the common impact of the thermal dynamical inducing compensate descent of Qinghai-Xizang Plateau（QXP） topography on the large scale and Fohn effect on leeward side of East Tianshan and Arjinshan orography on the meso-scale.And also there is a obvious extending