COASTAL SEA-LEVEL AND THE LARGE-SCALE CLIMATE STATE - A DOWNSCALING EXERCISE FOR THE JAPANESE ISLANDS

A major problem which is envisaged in the course of man-made climate c hange is sea-level rise. The global aspect of the thermal expansion of the sea water likely is reasonably well simulated by present day clim ate models; the variation of sea level, due to variations of the regio nal atmospheric forcing and of the large-scale oceanic circulation, is not adequately simulated by a global climate model because of insuffi cient spatial resolution. A method to infer the coastal aspects of sea level change is to use a statistical ''downscaling'' strategy: a line ar statistical model is built upon a multi-year data set of local sea level data and of large-scale oceanic and/or atmospheric data such as sea-surface temperature or sea-level air-pressure. We apply this idea to sea level along the Japanese coast. The sea level is related to reg ional and North Pacific sea-surface temperature and sea-level air pres sure. Two relevant processes are identified. One process is the local wind set-up of water due to regional low-frequency wind anomalies; the other is a planetary scale atmosphere-ocean interaction which takes p lace in the eastern North Pacific.