Added values of regional multi-ensemble dynamical and statistical downscaling in CORDEX Asia

To develop reliable regional climate information for climate change adaptation measures, we assess added values of regional multi-ensemble dynamical and statistical downscaling in collaboration with researchers of geoscience, social science and humanities, and officials of local governments in Japan and CORDEX Asia. We conducted dynamical downscaling experiments with horizontal grid spacing of 5km and 2km to reproduce regional climate information. We examine the performance of the regional climate model (NHRCM) to represent severe precipitation events occurred around Gifu and Nagano region. To examine the performance in ungauged mountainous regions, the runoff analysis was conducted. It indicates the overestimation of precipitation. We conduct the ensemble downscaling experiments using database for Policy Decision making for Future climate change (d4PDF) to detect the climate change impact in this region. Multi-model large ensemble regional climate scenarios over Japan and CORDEX Asia are developed by using CMIP5 GCMs (RCP2.6 and RCP8.5) and a statistical downscaling (Bias Corrected Spatial Disaggregation (BCSD)) to investigate uncertainty of projected change associated with structural differences of the GCMs for the periods of historical climate (1950-2005) and near future climate (2026-2050). Uncertainty range information of the regional climate scenarios support various regional adaptation measures and informed decision making.