CRUISE SUMMARY
1 Ship and Cruise code
      R/V MIRAI : MR00-K06
2. Main Research Area:
       Arctic Ocean (Chukchi Sea and Beaufort Sea)
3. Periods and Ports of Call
Leg-1: August 4 (Sekinehama, Japan) to August22 (Seattle, USA)
Leg-2: August24 (Seattle, USA) to (Victoria, Canada)
August27 (Victoria, Canada) to October 3 (Dutch Harbor, USA)
Leg-3:

 October 4 (Dutch Harbor, USA) to October 14 (Sekinehama, Japan).
4. Chief Scientist on Board:
       Dr. Takatoshi TAKIZAWA
Ocean Observation and Research Department, JAMSTEC
5. Background
      

  For the last few decades, we have come to realize the vulnerability of the Arctic and its residents to environmental and associated social changes. Climate model studies indicate that the Arctic environment may react particularly sensitive to global climate change. The recent observational studies reveal that the Arctic is in the midst of change extending from the top of atmosphere to below 1,000m in the ocean. Some changes appear to have begun as early in the 1970's, but many in the late 1980's or early 1990's. The lack of dense environmental data coverage in the Arctic due to inaccessibility or lack of long-term, continuous measurement stations, is a barrier to progress of modeling studies for global change prediction.
  Because of its unique environmental conditions, better understanding of the Arctic region will contribute to basic research as well as a predictive capability for the impact of future change. Ice, snow, glaciers, and the permafrost, etc. in the Arctic are highly sensitive integrators and indicators of changes in environmental parameters such as the air temperature, the solar radiation and so on. Investigation of those can provide information about the fundamental processes, which regulate them, and the implications and effects of changes in the Arctic. This, in turn, requires efforts to conduct a long-term, systematic observation.
  "Mirai", with its large ice-strengthened sturdy hull, was launched in 1997 (Dimension; LxBxD = 128.58 m x 19 m x 13.2 m; 8,672 Gross tons). The ship is equipped with many state-of-the art oceanographic and marine meteorological instruments and is expected to act as a floating platform for sophisticated interdisciplinary researches. The ship, in particular, with its large size and its anti-rolling device of special design, is capable of undertaking missions to high-latitude and polar regions exposed to the extremely harsh weather and sea conditions.

6. Objectives
      

  The overarching objective of our observational work by R/V Mirai is to collect the in-situ observational data in the multi-disciplinary research fields that will allow the analysis and modeling of the biological, chemical and physical systems related to the Arctic and their impact on global changes, and the controlling processes in these systems.

         The research works onboard of this cruise are:
      (1) Ocean circulation and shelf-break dynamics in the Chukchi/Beaufort Seas
      • Conduct a CTD/water column survey and X-CTD observation along the Chukchi and Beaufort shelf-break as far east as ice conditions and time allow.
      • Deploy a mooring north of Barrow Canyon.
      (2) Carbonate chemistry
      • Observation of partial pressure of CO2 (pCO2), total alkalinity, total dissolved inorganic carbon (TDIC), dissolved oxygen and nutrients in order to assess the spatial and temporal variations of budget and flux of CO2.
      (3) Atmospheric and upper ocean geochemistry
      • Observation of hydrological, atmospheric and sedimentological properties to study geochemical and hydrological interactions between north Bering and Arctic Ocean, shelf-edge exchange processes, air-sea exchange and Arctic paleoenvironmental change.
      • Investigation of the dissolved and colloidal rare earth element (REE) concentration of Arctic seawater in order to complete their vertical profiles, illuminate the REE fractionation and demonstrate REE transportation in the Arctic Ocean
      • Observation of chemical properties in order to discover the distribution of trace elements, such as Cd, Co, Cu, Fe, Ni, Zn, V, Zr, Hf, Nb, Ta, Mo, W, U, and Mn, in the Beaufort Sea, Chukchi Sea, and Bering Sea.
      (4) Atmospheric science
      • Investigation of dynamic, thermodynamic and radiative properties of Arctic summer stratus and Polar lows by Doppler rador.
      (5) Bio-optics
      • Observation of photosynthetically available radiation (PAR) in order to construct a model to predict a primary production from satellite observation such as GLI (NASDA) and SeaWiFS (NASA) based on the Photosynthesis vs Irradiance curve experiment.


7. Results
      

  The Arctic cruise of R/V Mirai, MR00-K06, was carried out in the Bering Sea, Chukchi Sea, and Beaufort Sea from 4 August to 12 October 2000. The locations of CTD and XCTD casts are listed in Table 1 and Table 2, respectively. Figure 1 shows the CTD and XCTD stations in the Beaufort Sea, where we are mostly interested in. Our current researches are to clarify the oceanic structure and its variability around the Barrow Canyon and the Northwind Ridge, and to understand the shelf basin interaction in the western Arctic Ocean.



Figure 1: Stations of CTD (blue) and XCTD (red) in MR00-K06 and the ice edge at September 15, 2000.

    7.1 Observations along the shelf-break of the Beaufort Sea

            

Figure 2                              Figure 3                               Figure 4

Figure 2: MR99-K05 CTD stations and vertical sections of temperature and salinity along the shelf-break of the Beaufort Sea.
Figure 3: MR00-K06 CTD stations and vertical sections of temperature and salinity along the shelf-break of the Beaufort Sea.
Figure 4: MR00-K06 XCTD stations and vertical sections of temperature and salinity along the shelf-break of the Beaufort Sea.

    7.2 Observations across the shelf-break of the Beaufort Sea


Figure 5


Figure 6
Figure 5: MR00-K06 XCTD stations, vertical sections and profiles of temperature and salinity along 158W30'.
Figure 6: MR00-K06 XCTD stations, vertical sections and profiles of temperature and salinity along 157W.

    7.3 Observations along the Barrow Canyon

Figure 7

Figure 7: MR00-K06 XCTD stations and vertical sections of temperature and salinity along the Barrow Canyon.

    7.4 Difference in the oceanic structure between the east and west of the Barrow Canyon
        
Figure 8
Figure 9

Figure 8:
MR00-K06 CTD stations, vertical sections and profiles of temperature and salinity from the Barrow Canyon to the Mackenzie Bay.

Figure 9:
MR00-K06 CTD stations, vertical sections and profiles of temperature and salinity from the Barrow Canyon to the Northwind Ridge.