Temporal-Spatial Distribution of Stable Isotopes in Precipitation and Its Relationship with ENSO over the North America

The characteristics of temporal-spatial distribution of δ~(18)O in precipitation and its relationships with temperature,precipitation amount and ENSO were analyzed in this study.The analyses show that the latitudinal distribution of the mean δ~(18)O in precipitation is very remarkable in the North America,regardless over lands or oceans.The mean δ~(18)O differences between continent and ocean are less besides high latitudes.With increasing latitude,the δ~(18)O in precipitation decreases quickly.It is found that the temperature effect appears over the whole North America continent,and becomes much more marked with increasing latitude.The variations of extension and intensity characterize a distributional difference of temperature effect on different seasons.The amount effect happens mainly in low-latitude oceans,east coast of the low-middle-latitude Pacific Ocean and northwest coast of Gulf Stream.However,no amount effect in inland.Similarly,the variations of extension and intensity characterize also a distributional difference of amount effect on different seasons.In inland and high latitudes of the North America,the Δδ~(18)O displays greater positive value corresponding to the distinct temperature effect;in low-latitude oceans,it does smaller or a negative value;and in the same latitudes,Δδ~(18)O in land is markedly greater than that in ocean.Furthermore,there are distinct positive correlations between SST in Nino-4 and δ~(18)O in precipitation at Ottawa and Midway Island that stand for continental and oceanic situations respectively,in which,the continuous correlations between the precipitation δ~(18)O in May and SST in Nioo-4 are remarkable,showing that the strong signal form ENSO has important impact on the variations of stable isotopes in precipitation of the land and the ocean in this period.