Outline of Main Research Theme for
Research Vessel “MIRAI” during fiscal year 2008

1. Cruise Code :
MR08-04

2. Main research theme:
R/V Mirai International Polar Year 2008 cruise

3. Objectives:
Substantial sea ice reduction has been observed since late 1990s from satellite sea ice concentration data. The spatial pattern of the sea ice reduction is not spatially uniformed, but rather disproportionally large in the Pacific sector of the Arctic Ocean. Based on these observational evidences, we hypothesized that Pacific inflow is a key player causing the anomalous sea ice reduction. To identify the mechanism affecting these changes is one of our mid-term science goals. The Mirai 2008 cruise will be Japan-led IPY activity in the Arctic Ocean.
IPCC’s recent assessment report (AR4) (or recently published IPCC assessment report) projected the sea ice cover in the Arctic Ocean during late summer would disappear by the end of this century in most of the models. However, the timing of the disappearance differs from model to model. To prepare ourselves for the “near future” global changes and avoid the inconvenient environment changes, real observational data which contributes to reduce uncertainty of future prediction, especially the fate of sea ice cover, is required now.

4. Outline of observation:
Environment in the Arctic Ocean is rapidly changing. For example, during the last decade, sea ice cover off Pacific Sector of the Arctic Ocean was decreased from 70% to 20%. To understand the mechanisms of the rapid changes in the Arctic Ocean, observation with time interval that resolves the rapid changes is required. Year 2008 is the timing to revisit the sections that were also occupied by the last Mirai cruise in 2004. This Mirai 2008 cruise is identified as a part of IPY activities. Therefore, it will be coordinated with other international cruises in the Pacific sector of the Arctic Ocean.
In order to examine the influence of Pacific inflow, variations/changes of freshwater storage and circulation pathway, the target area for hydrography is planned to cover the full span of the southern Canada Basin from Canadian Beaufort Sea to western Canada Basin near the Mendeleyev Ridge (ref. map). In the 2008 cruise, Bering Sea is also covered (or included) to investigate linkage between Bering Sea and Arctic Ocean. In addition to hydrography, mooring observation on the major pathways of Pacific water is scheduled. The data will be used to evaluate volume, heat and freshwater flux into the Arctic Ocean from the south.


5.Main research area:
Main research area is the Arctic Ocean north of the Bering Strait (Southern Canada Basin, Beaufort Sea, and Chukchi Sea). Bering Sea is also research area, but is not main area.

NOTE: The research area depends on sea ice condition.

6.Cruise period:
Aug. 16, 2008 (Sekinehama)
TRANSIT
Aug. 17, 2008 (Hachinohe)
TRANSIT
Aug. 26-28, 2008 (Dutch Harbor)
OBSERVATION
October. 11, 2008 (Dutch Harbor)


7. Ports of call (tentative):
Dutch Harbor
(Barrow, Nome: If embarkation and disembarkation of scientists, technicians and others are required.)

8. Proponent of main research theme:
Dr. Koji Shimada
Institute of Observational Research for Global Change
Arctic Ocean Climate System Group
JAMSTEC
2-15, Natsushima, Yokosuka 237-0061,
JAPAN

9. Contact person for inquiry about this cruise:
Dr. Koji Shimada
Institute of Observational Research for Global Change
Arctic Ocean Climate System Group
JAMSTEC
2-15, Natsushima, Yokosuka 237-0061,
JAPAN

PHONE: +81-46-867-9485
FAX: +81-46-867-9455
Email:

10. Remarks：