Compar ison Analysis of Environmental Changes Between Sahel and Agro- pastor al Zone in Nor thern China
近百年中国华北农牧交错带与非洲Sahel 地区环境变化的比较分析

Sahel is similar to agro~pastoral zone in Northern China in some aspects concerning environmental characteristics and environmental change, and there are some obvious linkages between them. The comparison analysis between them in precipitation, vegetation, drought events and dust storms can help better understand the variability of environment and climate in semiarid/arid regions in China and Sahel. Their interdecadal changes of precipitation have the similar trends. For Sahel, the interannual variability in precipitation is dominant before 1950s, while the interdecadal changes are outstanding from the mid of 1960s. A large portion of Sahel shows an increasing trend in NDVI. The interdecadal change of precipitation may be an important factor for the occurrence of drought, and temperature may also play roles in the formation of drought. The dust storm frequency has some evident relationship with precipitation on the interannual and interdecadal timescales, and the annual mean temperature and synoptic variability also have some influence on it. In agro-pastoral zone in Northern China, the interannual change is an outstanding characteristic in annual precipitation. In the north and east part of the zone vegetation experiences the increasing trend, and the south part shows a decreasing trend. The interdacadal change of precipitation played a role in the forming of drought events, but the same amount precipitation reduction may cause different drought in intensity. The spring dust storm frequency has tight relationship with previous winter temperature and synoptic variability, and also has some link with spring precipitation.