Physical Oceanography, Climate Dynamics
We are developing numerical models of the ocean and the climate andapplying those models to researches on the oceanic circulation of variousspatio-temporal scales and its influences on the climate. We are currentlyfocusing on the following issues.
1. Dynamics of oceanic global thermohaline circulation: The oceanic globalthermohaline circulation is one of the important factors controlling long-term stability and large-scale changes of the climate, but there stillremain many unknown aspects in it. It is known to be controlled by variousphysical processes such as sea surface fluxes (of heat, freshwater, andmomentum), deep water formation, mixing due to small scale eddies, andturbulent mixing. By investigating the oceanic global thermohalinecirculation from a wide range of view points, we aim to reveal its actualstate and understand its dynamics.
2. Polar oceans and climate: The polar oceans are exhibiting the largestchanges in the World Ocean under the recent global warming of climate.They are also important as the region of deep water formation which actsas the starting point of the oceanic global thermohaline circulation. Onthe other hand, progress of sciences on the polar oceans is slow comparedwith the other oceanic basins because they are difficult to be observedand they are under special situations such as interaction with thecryosphere. We are conducting modeling studies on the polar oceans underclose ties with observational research groups to know their actual state.By so doing, we aim to reveal the role of the polar oceans in the globalocean circulation and the climate.
3. Coastal and continental shelf regions and the global ocean: Theoceanic global circulation and material cycles are heavily affected byriverine input of freshwater and dissolved substances. Oceanic phenomenain coastal and continental shelf regions are controlled by physical,chemical, and biological processes which are significantly differentfrom those in the open ocean. Exchanges of water between those regionsand the open ocean are also controlled by peculiar physical processes.By studying these processes, we aim to obtain a global syntheis of theoceanic global circulation and material cycles.
4. North Pacific ocean circulation and climate: The Kuroshio, one of thestrongest currents in the World Ocean, has a large impact on the climateand fishery of not only around Japan but also over the entire Pacificregion. The Kuroshio is known to exhibit high and special variability.It is also suggested that oceanic processes associated with suchvariability are important factors controlling oceanic CO2 absorption andacidification. By studying the currents in the North Pacific and theirvariability, we aim to understand their role in climate variations andoceanic material cycles.
1. Kusahara, K., H. Hasumi et al. (2017): Modeling ocean-cryosphere interactions off the Adelie and George V Land coast, Journal of Climate, 30, 163-188.
2. Kawasaki, T., and H. Hasumi (2016): The inflow of Atlantic water at the Fram Strait and its interannual variability, Journal of Geophysical Research Oceans, 121, 502-519.
3. Hasumi, H. (2014): A review on ocean resolution dependence of climate biases in AOGCMs, CLIVAR Exchanges, 65, 7-9.