Hydrogen and oxygen isotopic characteristics of precipitation in coastal areas of Japan determined by observations for 23 years at Akita and for 1-2 years at other several localities

Dansgaard (1964) found another important characteristics of meteoric water, that is, the hydrogen and oxygen isotopic ratios of meteoric water both correlate to annual mean air temperature. Dansgaard (1964) also investigated processes regulating the isotopic ratios of precipitation and reported that variations in the isotopic ratios of precipitation are caused by isotopic fractionation occurring in source vapor supplying and cloud forming processes and that their global features are caused by succession of those isotopic fractionations from low to high latitudes. Jouzel et al. (1987) explained such a global distribution of the isotopic ratios of precipitation by results obtained by computer simulation based on an atmospheric general circulation model, and such of computer simulation has since been applied to explain various problems about isotopic ratios of precipitation (e.g., Yoshimura, 2009). Regarding hydrological problems, many studies have been carried out to explain the origin of ground water, runoff Hydrogen and oxygen isotopic characteristics of precipitation in coastal areas of Japan determined by observations for 23 years at Akita and for 1–2 years at other several localities