Abstract:

Using monthly mean air temperature data from 101 meteorological stations during 1961-2003 in the entire Inner Mongolia and the method of Rotated Empirical Orthogonal Functions (REOF), we implemented a regionalization according to consistency in air temperature variations of the four seasons, and analyzed seasonal and regional differences of air temperature variations. The seasonal air temperature changes indicate an apparent east-west difference in Inner Mongolia. The air temperature fields of spring, autumn and winter could be divided into two regions, namely, the West Region and the East Region, whereas the air temperature field in summer could be classified into three regions, namely, the West Region, the Southeast Region and the Northeast Region. In terms of the interannual variation, the seasonal air temperatures in each region experienced an obvious transition from decrease to increase during the recent 43 years except the Southeast Region in summer, and the turning points appeared either in the middle and late 1980s (in the East Region of spring and summer, and in the East and West Regions in autumn and winter) or in the early and mid-1990s (in the West Region of spring and summer). Dealing with the linear trend, the slope and significance of increased temperature trends in the East Region are larger than in the West Region during spring and summer, whereas the slope and significance of increased temperature trends in the West Region are larger than in the East Region during autumn and winter. Generally speaking, the most significant temperature increase appeared in winter and summer and then in spring, and the slightest temperature increase was shown in autumn.

Key words: air temperature changes, seasonal and regional difference, REOF, Inner Mongolia