Spatio-temporal Variation Characteristics of Cooling Degree Days and Heating Degree Days in South China

With the daily mean temperature data form 1961 to 2008 at 110 meteorological stations in South China, the annual cooling degree days and the annual heating degree days are calculated, their spatio-temporal variation characteristics are analyzed, and the relationship between degree days and annual mean temperature is investigated. The results show that the geographic distribution characteristics of annual cooling degree days in South China are that they are larger in southern part while smaller in northern part, larger in valleys and plains while smaller in mountain areas. As for annual heating degree days, they are getting larger from south to north. The annual cooling degree days tend to increase significantly since 1983, especially, the increase trend has been more obvious since 1998. Contrarily, the annual heating degree days tend to decrease since 1986, and the decrease trend has been more obvious since 1997. There is high correlationship between annual cooling degree day, heating degree day and annual mean temperature. It is expected that the cooling degree days would be increasing with global warming, while the heating degree days decreasing.