Variations of sea surface height and flow fields in the western North Pacific and surrounding marginal seas
- (Research Institute for Applied Mechanics, Kyushu University)
The primary aim of this proposal is to extend our understanding of the sea height and flow fields in the western North Pacific and surrounding marginal seas. Heat and volume transport of the Kuroshio and Oyashio current systems will be investigated by combining altimetry data with in situ ob- servations and numerical models. Similarly, currents in marginal seas around Japan such as the Japan Sea and the Sea of Okhotsk will be described by combination of the altimeter data and in situ observations, including surface drifters. Variations of those currents in the marginal seas would be related to the Kuroshio and Oyashio current systems in the western North Pacific, but their direct observational evidences have not been sufficiently shown yet, due to difficulty related to their small-scale nature in the marginal seas. Especially, in the straits connecting to those marginal seas, where the depth is shallow and lands are close, our use of the altimetry data is significantly limited since their accuracy is quite poor. Use of the High-Frequency (HF) ocean radar data with high spatio-temporal resolutions and improved accuracy of the altimetry data in marginal seas together with dense coverage by multi-satellite use would provide better insights of such variations.
In this proposal, we shall continue in situ observations. They include hydrographic and mooring field observations, HF radars, and drifters. They are used for basic oceanographic studies, and may be eventually used as calibration/validation data for Jason-2/OSTM by any other OST-ST groups. Similarly, we shall maintain operational real-time Japan-GODAE data products produced by operating an ocean data assimilation system of Japan Meteorological Agency (JMA). Meanwhile, assimilated results from a more comprehensive model will be used for basic studies. In addition, gravity changes due to huge oceanic motions such as a large Kuroshio meander will be examined by use of a dense network of accurate gravity field measurements in Japan. We intend to obtain new understandings of circulations in the western North Pacific through those aspiring studies.