Habitable Japan Sustainability of atmospheric and oceanic environment as a survival basis of island country Japan Grant-in-Aid for Transformative Research Areas (A) (2024–2028)

Our group focuses on data assimilation (DA), which effectively combines observations and simulations. Our goal is to reproduce realistic and detailed atmospheric, oceanic, and biogeochemical environments for our research project. However, existing DA techniques fall short in capturing discontinuities at oceanic and atmospheric fronts, as well as in the interfaces like the sea surface and tropopause. Nonlinear phenomena, such as eddy detachment and intense convection pose additional challenges for proper assimilation. Moreover, coupled DA between the ocean and atmosphere, considering different time scales and various physical, chemical, and biological processes remains largely unexplored. The ocean surrounding Japan provides an ideal setting for our research due to active air-sea-biogeochemical coupling, discontinuities and nonlinearities. Motivated by this context, we aim to advance DA by improving techniques, evaluating observation values, designing effective observing systems, and obtaining insight into vertical coupling among ocean subsurface, troposphere, and stratosphere and into remote effects with DA methodologies.