中文摘要：

三大自然区（东部季风区、西北干旱区、青藏高原区）过渡地带，由于其特殊的地理位置，受到亚洲季风、中纬度西风环流共同影响，对气候变化的响应较为敏感。使用国际通用的柯本气候分类法和国内常用的积温与干燥度分类法，研究了97．5°～108°E，33°～41．5°N的三大自然区过渡地带1961q010年的气候带类型及其变化过程。并通过将各气候类型的面积变化与主要季风指数、西风指数和南方涛动等主要指数进行了对比，并计算了他们的关系，与此同时结合东亚各气候区气温及降水的变化模式探讨三大自然区过渡地带气候变化对各气候系统的响应。基于此项研究：夏季西风和东亚冬季风的增强会使该区域变湿，东亚夏季风、南亚夏季风增强则会使该区域海拔较低的区域变干，海拔较高的区域变湿。高原夏季风的增强则会使整个区域变干。北大西洋涛动增强，会使该区域变湿；厄尔尼诺增强（减弱），则会使该区域变干（变湿）。总体来讲，该区域的水分状况主要受控于中纬度西风带环流，虽然亚洲夏季风的增强有可能会增加该区域东南部的降水，但是根据计算出的干燥度和气候带类型变化，增温效应可能会抵消降水增加，从而使该区域变干。根据本项研究，三大自然区过渡地带受到多个气候系统的相互作用，气温及降水等单一指标，并不能完全代表该区域气候变化特征，气候带类型面积变化可以作为一个重要的指标运用于该区域气候变化评价。

英文摘要：

The transition area of three natural zones （Eastern Monsoon Region, Arid Region of Northwest Chi- na, Qinghai Tibet Plateau Region） is influenced by the Asian monsoon and middle latitude westerly circulation be- cause of its special geographical position. And it is more sensitive to global climate change. The Koppen climate classification, which is widely used in the world, and the accumulated temperature-dryness classification, which is usually used in China, were used to study the climate zones and changes in the region of longitude 97.5~ - 108~E, latitude 33~ -41.5~N, from 1961 to 2010. The changing areas of each climate zone were compared to the East Asi- an Summer Monsoon index, the South Asian Summer Monsoon index, the Summer Westerly index, the East Asian Winter Monsoon index, the Plateau Summer Monsoon index, the North Atlantic Oscillation index, the Southern Os- cillation index, NIN03.4 index, to explore the response of the transition area of three natural zones to each climate system. According to the results, this region will become wetter when the Summer Westerly or the East Asian Win- ter Monsoon is relatively strong. When the East Asian Summer Monsoon or the South Asian Summer Monsoon be- comes strong, the climate in low altitude region of the study area will easily become drier, and the climate in high altitude region of the study area is easily to become wetter. When the Plateau Summer Monsoon is relatively strong, the climate in the study area will easily become drier. When the North Atlantic Oscillation is relatively strong, the study area will easily become wetter. And when the E1 Nifio is relatively strong, or the Southern Oscillation is rela- tively weak, the study area will easily become drier. In general, the moisture status of this region is mainly con- trolled by the middle latitude westerly circulation. The enhancement of the Asian summer monsoon could increase the precipitation in the southeast part of this regional, but, according to the degrees of dryness and the types of cli- mat