Deuterium excess in precipitation and water vapor origins over Japan: A review

Abstract

Water vapor origins (i.e., the sources of evaporated moisture) were estimated based on the deuterium excess (=δD-8×δ¹⁸O, hereafter d-excess) in precipitation, which was primarily determined by relative humidity, sea surface temperature, and wind speed as water vapor evaporates and is conserved during the atmospheric moisture transportation process. This review summarizes observation studies on d-excess in precipitation and numerical studies about estimation of water vapor origin over Japan. Moreover, this review discusses the potential for using d-excess in precipitation as a tracer of atmospheric hydrological cycles. The results revealed that precipitation originating from the Sea of Japan was most likely not predominant in the region, other than on the Sea of Japan side, despite the fact that d-excess values in winter were above 20‰ or higher than in summer. On the other hand, high d-excess values in precipitation appeared to lead to a high contribution of water vapor evaporated from the Sea of Japan to precipitation during winter. These results suggest that the d-excess in precipitation has potential applications in estimating the contribution ratio of water vapor originating from the Sea of Japan. Combining these key findings with isotope mapping can provide useful information for paleoclimate research and water resource management.