A daily gridded precipitation dataset covering a period of more than 57 yr was created by collecting and analyzing rain gauge observation data across Asia through the activities of the Asian Precipitation—Highly Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE) project. APHRODITE's daily gridded precipitation is presently the only long-term, continental-scale, high-resolution daily product. The product is based on data collected at 5,000–12,000 stations, which represent 2.3–4.5 times the data made available through the Global Telecommunication System network and is used for most daily gridded precipitation products. Hence, the APHRODITE project has substantially improved the depiction of the areal distribution and variability of precipitation around the Himalayas, Southeast Asia, and mountainous regions of the Middle East. The APHRODITE project now contributes to studies such as the determination of Asian monsoon precipitation change, evaluation of water resources, verification of high-resolution model simulations and satellite precipitation estimates, and improvement of precipitation forecasts. The APHRODITE project carries out outreach activities with Asian countries, and communicates with national institutions and world data centers. We have released open-access APHRO_V1101 datasets for monsoon Asia, the Middle East, and northern Eurasia (at 0.5° × 0.5° and 0.25° × 0.25° resolution) and the APHRO_JP_V1005 dataset for Japan (at 0.05° × 0.05° resolution; see www.chikyu.ac.jp/precip/ and http://aphrodite.suiri.tsukuba.ac.jp/). We welcome cooperation and feedback from users.

Abstract: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 -HighlyResolved Observational Data Integration Towards Evaluation of the Water Resources" (APHRODITE) project. This product APHRO_JP 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).APHRO_JP enables diverse research, including validation of meso-scale models and analysis of the longterm extreme precipitation trend in Japan.

A coupled ocean-atmosphere climate model is used to depict changes in precipitation characteristics around Japan in the 21st century. A comparison between high (T106 atmosphere) and medium (T42) resolution versions for the present-day climate shows that the higher resolution version better represents not only the mean but also the frequency distribution of precipitation. The climate projection for the 21st century by the high resolution version shows that mean precipitation increases more than 10% in 100 years from the present, especially in warm seasons. Increases in frequencies of non-precipitating and heavy ( 30 mm day 1 ) rainfall days and decrease in relatively weak (1 20 mm day 1 ) rainfall days are significant.

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Accurate simulation of summertime convection associated with the Asian monsoon trough over the subtropical western Pacific is important but di‰cult to achieve in many general circulation models (GCMs). This study reports a case in which bias could be reduced by introducing a higher-resolution regional atmospheric model (RAM), two-way nested in an atmospheric GCM over the western Pacific. Additional partial-coupling experiments revealed that GCM bias correction was insensitive to the coupling domain. The two-way nesting e¤ect was similar to one phase of a leading mode of natural variability in the system. This is indicative that the twoway nesting model provides more realistic tropical heating that e¤ectively excites a correct phase of the intrinsic dynamical mode to reduce GCM bias.