Research

Impact of freshwater flux from the Kamchatka Peninsula on the thermohaline circulation in the North Pacific.

Grant-in-Aid for Scientific Research (A) (17H01156: PI; Humio MITSUDERA)

Biogeochemical processes in the Sea of Okhotsk and the linkage to the Pacific Ocean

We demonstrates the pivotal role of tidal mixing in the Kuril Island chain (KIC) for determining iron (Fe) supply to the euphotic zone of the Western Subarctic Pacific. Indeed, Fe derived from sediments in the Sea of Okhotsk is discharged through the KIC into the intermediate water mass (=800m) of the western North Pacific. The redistribution of this Fe-rich intermediate water by intensive mixing as it crosses the KIC is the predominant process determining the ratio of micronutrient (Fe) to macronutrients (e.g., nitrate) in subsurface waters. This process explains the significant phytoplankton growth and great seasonal variability observed in the Western compared to the Eastern Subarctic Pacific.

Systems in linking adjacent land with ocean

- Multi scale Researches and Integrated Comprehension -

Joint Research Program of the Institute of Low Temperature Science, Hokkaido University (Pioneering)

PI Seiya NAGAO (Kanazawa University)

The Amur - Okhotsk Consortium

The Amur-Okhotsk Consortium in a multilateral academic network to promote sharing of information on environment in the Pan-Okhotsk region and to make the best efforts toward cooperative environmental monitoring. The consortium is composed of academic researchers not only belonging to Japanese institutions but also to those in China, Russia and Mongolia. International Research Promotion Office of the Pan-Okhotsk Research Center plays a role in managing the consortium.

Website of Amur-Okhotsk Consortium

Numerical simulation of the Sea of Okhotsk

In the Sea of Okhotsk, dense shelf water (DSW) is produced as a result of sea ice formation. DSW flows out to the intermediate layer and transports chemical properties such as iron in a long distance. The DSW salinity is influence by the Amur River discharge and saline water intrusion from the North Pacific. High resolution numerical models are used to simulate such complicated features of the Sea of Okhots.

Dynamics of Soya Current

We installed High Frequency (HF) ocean radar stations around the SOYA/La Perouse Strait in the Sea of Okhotsk and have been monitoring seasonal and interannual variations in the Soya Warm Current (SWC) since 2003. From the observations, it is revealed that the velocity of the SWC reaches its maximum, approximately 1 m/s, in summer and weakens in winter.

Ocean physical processes in the Sea of Okhotsk

Ocean circulation in the Sea of Okhotsk has two features: sinking of dense shelf water formed by large sea ice production and vigrous vertical mixing by tidal flow. Their impact spreads in the Sea of Okhotsk and to the North Pacific, and thus affects the formation of the ocean/material circulations, and ecosystem. Interannual variation and warming trend around the Pan-Okhotsk region are changing the ocean environment through the above processes. For a better understanding of such formation and change of the climate around the Sea of Okhotsk, Pan-Okhotsk Research Center has conducted numerical simulations and observations.

Climate Changes reconstructed from alpine ice cores obtained from the northern North Pacific and Greenland

We obtained several ice cores from alpine glaciers at the northern North Pacific region to reconstruct climate and environmental changes for several hundred years and elucidate its mechanisms. Ice core analysis from Alaska indicated that storm activity in the Gulf of Alaska enhanced since 1970, and precipitation at Alaska increased with the enhancement of storm activities.