Verification of the isotopic composition of precipitation simulated by a regional isotope circulation model over Japan^*

* Originally presented at the IAEA International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, 11–15 May 2015, Vienna, Austria.

ABSTRACT

The isotopic composition (δ¹⁸O and δ²H) of precipitation simulated by a regional isotope circulation model with a horizontal resolution of 10, 30 and 50 km was compared with observations at 56 sites over Japan in 2013. All simulations produced reasonable spatio-temporal variations in δ¹⁸O in precipitation over Japan, except in January. In January, simulated δ¹⁸O values in precipitation were higher than observed values on the Pacific side of Japan, especially during an explosively developing extratropical cyclone event. This caused a parameterisation of precipitation formulation about the large fraction of precipitated water to liquid detrained water in the lower troposphere. As a result, most water vapour that transported from the Sea of Japan precipitated on the Sea of Japan side. The isotopic composition of precipitation was a useful verification tool for the parameterisation of precipitation formulation as well as large-scale moisture transport processes in the regional isotope circulation model.

KEYWORDS:

• Isotope circulation model
• isotope hydrology
• Japan
• oxygen-18
• precipitation

Acknowledgements

The author is also grateful to the anonymous reviewers for providing valuable comments, which helped improving the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Masahiro Tanoue http://orcid.org/0000-0003-1365-0187

Notes

* Originally presented at the IAEA International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, 11–15 May 2015, Vienna, Austria.

Additional information

Funding

This study was supported by the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Scientific Research(C) [grant number 24510256]; JSPS Grant-in-Aid for Young Scientists(B) [grant number 15K16310] and the cooperative research of the Atmosphere and Ocean Research Institute, The University of Tokyo.