¹Nihon University, College of Industrial Technology Narashino, Chiba, JAPAN

c03810@cit.nihon-u.ac.jp

　

²Ark Information System Chiyoda-ku, Tokyo,JAPAN

　

³Londo Columbia University, Lamont-Doherty Earth Observatory Palisades, New York, USA

　

As one of measures for controlling the emission of carbon dioxide (CO₂) into the atmosphere, attention is focused on making effective use of the ability of the ocean to absorb CO₂, and an evaluation is performed on the ability to isolate CO₂ from the atmosphere by emitting CO₂ into areas deeper than the middle layer of the ocean.

　

In the first stage of this research, the Pacific three-dimensional circulation model was revised to enhance the accuracy of the circulation model further. The wind-velocity value, observed from two satellites, (NSCAT and SSM/I), were applied as an ocean current driving force. Its calculation result roughly coincides with the results of existing documents. Particularly, the currents of which flow rate is relatively small such as Oyashio current, Indonesia passing ocean current and subtropical counter current are well reproduced.

　

When CO₂ emission is down in off Kona City, Hawaii, where liquid carbon dioxide ocean isolation was once planned, if it is deeper than 1.000 m, the dumped substances did not come up to surface layer and it is confirmed that the purpose of ocean dumping is achieved. And the substances dumped in at the surface layer shallower than 600 m deep is susceptible to sea surface flux and as it is in thermocline layer, it circulates very much, so ocean isolation in this depth is not realistic. And the CO₂ dumped at deep layer (deeper than 4.000 m) is susceptible to bottom topography and it is confirmed that it moves along the bottom shape. As it is surmised that ocean dumping at a very deep layer may deteriorate ecology of rare species living at sea bottom, it is not desirable.

　

The economically realistic water depth for ocean dumping of liquid carbon dioxide is considered at about 1.000 m - 1.500 m deep.

　

¹P. P. Shirshov Institute of Oceanology Russian Academy of Sciences Moscow, RUSSIA

smshap@sio.rssi.ru

　

²Moscow State University Moscow, RUSSIA

　

A comparison of wind driven geostrophic transport and velocity structure on the base of direct measurements of ADCP is delivered. The data for analysis was taken from two zonal transatlantic sections along 5^oN and 53^oN carried out in 2000 and 2001 respectively. Distribution of geostrophic current speed calculated from CTD data is similar to the ADCP measurements in the upper 600-m layer. The resulting zonally averaged ageostrophic mass transport is similar to the estimation by Eknan balance using shipboard wind. The results from low and higher latitudes are comparing.

　

　

¹Ocean Research Institute, The University of Tokyo Nakano Ku, Tokyo,JAPAN

sugimoto@ori.u-tokyo.ac.jp

　

²Frontier Research System for Global Change Yokohama, Kanagawa, JAPAN

　

Long-term historical data sets of T/S Oshoro-Maru of Hokkaido University reveal that horizontal distributions of climatological surface chlorophyll concentrations and mesozooplankton biomass in the subarctic North Pacific and the marginal sea in summer generally follow a positive correlation at the regional scale, but negative correlations at the regional scale. Zooplankton biomass in the western and central subarctic Pacific as well as the Bering Sea were high after mid 1960s till the late 1980s, however, in the Oyashio, it decreased after the late 1970s. To understand on the geographical differences in seasonality and their limiting factors, seasonal and inter-annual variations in physical parameters of the subarctic North Pacific were analyzed by using the JODC (Japan Oceanographic Data Center) and JMA (Japan Meteorological Agency) data sets. The results reveal that the spring blooming of high values appeared in the Oyashio, Okhotsk Sea, and Bering shelf water. Whereas in the western, central, eastern Pacific, and the Bering basin water showed relatively low values without spring blooming. The upper MLD (mixed layer depth) in the Oyashio and the Sea of Okhotsk becomes shallower than 40 m depth in April, but the MLD in the western, central, eastern Pacific, and Bering basin remained below 100 m depth. The timing of the seasonal pycnocline formation and its interannual variation might be playing an important role on the seasonality, abundance of plankton biomass and their geographical differences, in the subarctic North Pacific.

　

　

¹Nihon University, College of Industrial Technology Chiba, JAPAN

wada@civil.cit.nihon-u.ac.jp

　

²Laboratory of Aquatic Science Consultant Corp. Tokyo,JAPAN

　

³Ark Information System Tokyo,JAPAN

　

Research has been underway to clarify a situation resulting the dumping of radioactive wastes into the Arctic Ocean (especially, the Kara Sea and the Barents Sea) by the former Soviet Union.

　

As the first step of research, the mechanism of flows in the local areas (the Barents Sea and the Kara Sea) and the regional area (the whole Arctic Ocean) was investigated. Using the observation data (water temperature and salinity), the flow analysis using box model (a hybrid box model) was conducted, taking into account river flows and density structures in the seas. The results thus obtained agreed with the observed features in many aspects. Especially, streamflows in the Norwegian Sea, Barents Sea, Kara Sea and Laptev Sea showed fairly realistic features. The flow field in the surface layer in the central part of the Arctic Ocean differed from that in the known data. In the middle and deep layers, however, there was a streamflow that agreed with the information as cyclonic circulation. In the offing east of Greenland where the current is weak, a streamflow equivalent to the Greenland current was recognized.

　

As the second step of research, concentration analysis was conducted on the basis of a release scenario with considerations given to nuclide decay, mixing, scavenging and interaction between undersea particles and the bottom sediment layer, using the results of the flow analysis. A clear difference was recognized in the diffusion distribution according to the properties of nuclides, and the concentration in the sediment is 2-digit higher than that in the seawater when the distribution factor of value is large as in Pu239.