The relation between isotopic compositions of precipitation and surface air temperature provides a unique tool for paleoclimate studies

among which the relation between long term changes in δ 18O of precipitation and surface air temperature at different stations or in a given location seems to be the most appropriate to paleoclimatic reconstructions. Analysis was conducted on monthly and annual mean δ 18O content of precipitation and surface air temperature at spatial and fixed locations by using the data of China (1985～2002) in Global Network of Isotopes in Precipitation (GNIP) Database. This study shows that there is a positive correlation between δ 18O of precipitation and surface air temperature for stations located in north of 34 ° ~ 36 ° N latitudes. The seasonal δ 18O-temperature gradient derived from the monthly data of 12 stations in northern China is about 0.34‰℃-1. The δ 18O-temperature gradient

however

derived from the long term annual mean data of 13 stations

is about 0.52‰℃-1

which is substantially larger than the seasonal gradient.