Dynamical downscaling of future sea-level change in the western North Pacific using ROMS

Abstract:

The western North Pacific to the east of Japan is one of the regions where sea-level rise is predicted to the larger than the global mean in CMIP5 models as shown in IPCC AR5. One of the causes of the spatial variations of the sea-level is change in ocean circulation, and this effect can be important in western boundary regions, where changes of strong western boundary current can cause large sea-level changes. However, the current climate models cannot properly represent western boundary currents due to coarse model resolution. Therefore, it is desirable to perform downscaling of future sea-level changes using a regional ocean model with a high model resolution for western boundary current regions using forcings and boundary conditions taken from climate model outputs.

This study investigates future regional sea-level rise by performing dynamical downscaling in the western North Pacific, using the regional ocean model system (ROMS) with eddy-permitting 0.25-degree resolution over the North Pacific. In order to evaluate possible extremely large regional sea-level rise, the Model for Interdisciplinary Research on Climate Earth System Model (MIROC-ESM) under RCP8.5 scenario is chosen because this model exhibits large sea-level rise among CMIP5 models in this region. ROMS are run for two epochs; one is 1950-2000 and the other is 2051-2100, and the last 20-years are analyzed. The model integration is now ongoing, and the major differences between the two runs will be reported at the meeting.