Two kinds of dry and wet climate type evaluation method application in the Inner Mongolia Region

The study of dry wet climate type was very common at home and abroad,but it hasn't seen Holdridge potential evapotranspiration rate(PER)method and Wen-Duo Xu Humidity index(HI)about dry and wet climate type division contrast report. The paper uses 116 weather station data(1984-2013)and analyze the types of dry and wet climate change in the Mongolia by the two methods. The results from PER indicated that there are arid region and extremely arid areas 278 495 km2,semi-arid zone andsubhumid area 278 495 km2,humid region278 495 km2;while result from HI showed arid regionand extremely arid areas 388 832 km2,semi-arid zone and subhumid 579 754 km2,humid region 278 495 km2. The difference division from two methods mainly located in the semi-arid and subhumid area. The same trends of interdecadal variation was that total area of arid region and semi-arid zone is increasing,but semi-humid area is decreasing with years. PER and rainfall distribution is obvious,and HI can illustrate more comprehensive influence of the temperature and precipitation. Considering the characteristics of underlying surface conditions the HI is more suitable for dividing the wet and dry area of Inner Mongolia region. Moreover,from analysis of 30 years temperature and precipitation,Inner Mongolia region,has a distinct warming and drying trend,but the decreasing trend of precipitation belongs to normal climate fluctuations.