Research Goals
The goal of this research project is to identify an active role of the midlatitude ocean in the formation of the atmospheric circulation and surface environment and their variability, and to understand the underlying mechanisms, in attempting to establish a new paradigm of the climatological research. The primary target area of our project is the vicinity of Japan, where the most distinct "hot spot" in the extratropical climate system.
Specific research targets are the following:
- I. (i) Atmospheric and oceanic instability arising from the "meridional contiguousness" between the tropical heat and the polar cold caused by the Kuroshio and Oyashio Currents and the eastern Asian monsoon; (ii) instability-generated meso-scale ocean eddies and precipitating weather systems, and their multi-scale interactions with large-scale circulation systems in the ocean and atmosphere; (iii) specific processes of the interactions that are involved in a huge amount of heat and moisture release from the ocean to the atmosphere; and (iv) influence of the interactions on the surface environment including the marine ecosystem.
- II. Climatic influence of the "thermal contiguousness" manifested as the sharp land-sea thermal contrast between the monsoon Asia and the North Pacific. Specifically, (i) large-scale atmospheric waves forced in winter by strong continental cooling and the heat release from the Kuroshio; (ii) the wave-induced coupled variability from the upper ocean into the stratosphere through the troposphere and its global influence, especially over the Northern Hemisphere and the Tropics.
- III. (i) Influence of such large-scale circulation systems as the East Asian summer and winter monsoons and the Tsushima Warm Current on upper-ocean temperature and sea-ice distributions over the western North Pacific and the marginal seas (East China Sea, Sea of Japan and Sea of Okhotsk); (ii) influence of the upper-ocean temperature and sea-ice distributions both on summertime cloud systems associated with the Baiu front or typhoons that cause torrential rainfall, and on the formation of meso-scale cyclones or precipitation systems and explosive cyclones that cause severe snowfalls.
Our ultimate goal is to obtain comprehensive understanding of (i) the mechanisms of tropical, midlatitude and polar phenomena involved in the "two-way (meridional and zonal land-sea) thermal contiguousness" over the Far East and western North Pacific and (ii) its role in the formation and variability of the extratropical climate system and surface environment system, both of which have been overlooked until recently. This is an unexplored area in climate study, which is nevertheless very important and essential in deepening our understanding of the global environmental system changing under the global warming.