Development of APHROJP, the first Japanese high-resolution daily precipitation product for more than 100 years

We constructed historical (1900–) high-resolution (0. 05° × 0. 05°) daily precipitation data over the Japanese land area as part of the product of the “Asian Precipitation – Highly-Resolved Observational Data Integration Towards Evaluation of the Water Resources” (APHRODITE) project. This product APHROJP is derived from rain gauge observations and is intended to accurately represent both mean and extreme values. Due to new interpolation techniques developed in APHRODITE, estimation accuracy for orographic precipitation is improved, and bias for long-term amount is reduced, even for the early 20th century in which the observation network was sparse in space. Moreover, the product can be used for statistical analysis of heavy precipitation up to about 150 mm/day, over a long term period (≥ 100 years). APHROJP enables diverse research, including validation of meso-scale models and analysis of the longterm extreme precipitation trend in Japan.