[A-HW25_2AM1] 同位体水文学2014

[AHW25-04] 2013年に観測した日本全国の降水安定同位体比の初期解析の結果

*一柳 錦平¹、田上 雅浩² (1.日本水文科学会同位体マッピングワーキンググループ、2.熊本大学)

キーワード：Stable isotopes in precipitation, d-excess, Japan, IOP2013

Stable isotopes in precipitation are used for a proxy of climate change, which is related with temperature or precipitation amount. By using the atmospheric general circulation model with stable isotopes in water, water vapor origins (where the water vapor evaporated from?) can be estimated to determine the air mass transportation process. There are a lot of studies to observe stable isotopes in precipitation at only one or a few places in Japan. Tanoue et al. (2013) revealed seasonal variation and spatial distribution of stable isotopes in precipitation over Japan from the previous observational data at about 50 stations. However, spatial and temporal variations of stable isotopes in precipitation across Japan are still unknown, because a specific site and an observation period are different among the previous studies. Intensive observation of stable isotopes in precipitation over the whole Japan is required during the same period. The Isotope Mapping Working Group of Japanese Society of Hydrological Sciences was conducted intensive observation of stable isotopes in precipitation throughout the year in 2013 (IOP2013). More than 2,000 precipitation samples are already collected at about 50 stations, and are analyzing its stable isotopic ratios by the Isotope Ratio Mass Spectrometer (Delta-V, Thermo Scientific) in Kumamoto University. Stable isotopic ratios in precipitation across Japan will be considered the relationships with locations (i.e. latitude, altitude, and distance from the coastline) and meteorological elements (i.e. temperature, precipitation amount, winds, specific humidity). Also, water vapor origins are estimated by using atmospheric general circulation model with stable water isotopes. Finally, the equations to reproduce stable isotopic ratios in precipitation at a specific place in Japan will be determined by its location and/or meteorological elements. It's a useful for the paleo-climate change as a proxy data of temperature and/or precipitation amount in the past. In this study, we present the preliminary result of the IOP2013.