Importance of wind-induced undercatch adjustment in a gauge-based analysis of daily precipitation over Japan

Abstract

We produced a new gauge-based analysis of daily precipitation over Japan from 1981 to 2000 on a 0.01° grid. Wind-induced undercatch was adjusted at each observation station, and orographic effects were considered in the process of spatial interpolation from station data to the gridded product. The resulting gridded gauge-based analysis of precipitation was validated against observed river discharge data. The validation demonstrated that the product is reasonable, mostly because of the undercatch adjustment. Based on the resulting product, Japan receives nearly 2000 mm/year of precipitation on average, which is approximately 10% larger than commonly thought.