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Researches of Pan Okhotsk Research Center

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 Islands chain (KIC) for determining iron (Fe) supply to the euphotic zone of the Western Subartic Pacific. Indeed, Fe derived from sediments in the Sea of Okhotsk is discharged through the KIC into the intermediate water masses (~ 800 m) 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.

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 flow out to the intermediate layer and tranports chemical properties such as iron in a long distance. The DSW salinity is influenced 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 Okhotsk.

Dynamics of the Soya Warm Current

We installed High Frequency (HF) ocearn 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 observation, 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 vigorous 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 Okhostk, Pan-Okhotsk Research Center has conducted numerical simulations and observations.

Reconstruction of climate and environment changes at the northern North Pacific region using alpine ice cores.

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 Kamchatka indicated that solar insolation at Okhotsk region in 1950-70 was higher, and the variation of insolation was associated with Arctic Oscillation. 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 activity.

The Amur-Okhotsk Consortium

The Amur-Okhotsk Consortium is 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 acadeic researchers not only belonging to Japanese institutions but also to those in China, Russia and Mongolica. International Research Promotion Office of the Pan-Okhotsk Research Center plays a role in managing the consortium.