PRODUCTS

CRUISES

CABOS CRUISE 2003

PRELIMINARY REPORT

on the scientific experiments in the Eurasian and Canadian basins of
the Arctic Ocean onboard the icebreakers “Kapitan Dranitsin” and “Louis St. Laurent”
August-September 2003-04

In the early 1990s, oceanographers began to report major anomalies in the water masses of the Nansen, Amundsen, and Makarov Basins - a change in the extent of Atlantic water, increased temperature of the Atlantic water, and a warming of the "cold pycnocline." These changes roughly coincided with global increases in surface air temperature, reduction in arctic sea-ice extent, and reduction of arctic sea-ice thickness. The temporal variability of heat and salt flux from the Arctic Ocean into the North Atlantic has long been recognized as an important determinant of global ocean convection. By the end of the 1990s, the variability of heat and salt flux from the Atlantic Ocean into the Arctic Basin was also seen as an important component of the global climate system.

The possibility of long-term support led researchers to propose NABOS (Nansen Amundsen Basins Observational System) as one of the major International Arctic Research Center (IARC) initiatives. The scientific objective was widely recognized - to measure temperature, salt, and current along the principal pathways transporting water from the Nordic Seas into the central Arctic Basin (Figure 1). The scope of the field problem clearly calls for international cooperation/coordination, a task commensurate with an international center. NABOS is currently conducted jointly by the IARC, the Institute of Marine Science (IMS), and the Arctic and Antarctic Research Institute (AARI), Russia. CABOS (Canadian Basin Observational System), an observational program complementary to NABOS, is jointly initiated by IARC and the Institute of Ocean Sciences (IOS), Canada. By now NABOS has become a major IARC initiative.

Figure 1. Locations of planned and previously deployed moorings.

Brief history

In advance of recommending NABOS to the international community, IARC researchers decided on a pilot project (2001-2002) to demonstrate the feasibility of the basic measurement program. IARC proposed to deploy two moorings, one mooring at the slope of the Laptev Sea (jointly with AARI) and another mooring in the Canada Basin (jointly with IOS). On September 23, 2001, scientists from IARC and IOS deployed a mooring in 460 m of water at the mouth of Mackenzie Canyon from the Canadian icebreaker "Sir Wilfrid Laurier". In September 2002, the Mackenzie Canyon mooring was recovered, and a second mooring was deployed in 1117 m of water in the southern Beaufort Sea. This mooring was deployed specifically to monitor the warm Atlantic water boundary current flowing around the perimeter of the Canada Basin. One more mooring was deployed in 2002 from the Russian icebreaker “Kapitan Dranitsyn’’ in 2680 m of water on the slope of the Laptev Sea accompanied by attendant oceanographic, meteorological, and ice observations. Our successful pilot project demonstrated several key issues: political approval for moorings in the Russian Exclusive Economical Zone (EEZ), ship logistics required for successful deployment/recovery of moorings, and design and assembly of the mooring.

Program Methods

The primary monitoring tool of the NABOS/CABOS program will be a series of moorings placed at carefully chosen locations around the Arctic Ocean. Time series obtained from these moorings will allow separation of synoptic-scale signal (e.g., eddies, shelf waves) from longer-term climatic signal. Located along the major pathways of water, heat, and salt transport, such moorings should capture climatically important changes in oceanic conditions. The NABOS/CABOS moorings will operate for one year at a time, with replacement every year. A gradual increase in the number of moorings is planned, from two deployed in summer 2002, to the full-scale monitoring system (Figure 1) after several years.

Most NABOS/CABOS moorings will be equipped with the "McLane Moored Profiler" (MMP). The same tool was used on our pre-NABOS/CABOS mooring deployed in the Beaufort Sea in summer 2001 (Figure 1). This instrument is capable of profiling vertically along the mooring line, covering up to 106 m during its deployment. The MMP is typically equipped with a CTD (Conductivity/ Temperature/Depth) sensor and a three-component acoustic velocimeter. The up-and-down motion of the profiler is programmable, making it possible to focus on specific depth ranges and time periods, giving a high degree of flexibility in designing a sampling scheme.

Progress Report and Accomplishments in 2002-03

Intense preparation efforts have been in progress during the last 12 months. They are part of our ongoing collaborations developed over many years with our national and international colleagues. A NABOS workshop was held in November 2002 in St. Petersburg, Russia. Representatives from AARI, IARC, RosGidroMet (the Russian federal agency directing environmental work), Russian Ministry of Science and Technology, and several other Russian and German institutions participated. As a result of these and other efforts we obtained the long-anticipated permission from the Russian authorities to deploy our first mooring within the Russian EEZ.

On 26 August 2003, the Russian icebreaker "Kapitan Dranitsyn" left Kirkenes, Norway, on a 22-day voyage to the northern Laptev Sea. Ten Russian scientists from AARI, several students from St. Petersburg State University and representatives of the Russian Navy and FSB (an FBI-like Russian agency), together with four researchers from the University of Alaska Fairbanks and two scientists from the Quebeck University, Canada, were aboard the icebreaker to recover and deploy the NABOS MMP-equipped moorings in the Eurasian Basin (Figures 2 and 3), and to conduct attendant oceanographic, meteorological, and ice observations on the Laptev Sea slope. Twenty-six CTD profiles accompanied by water sampling were taken during the cruise (see attached Table 1 and following mooring schematics). Six conventional ice buoys and one ice mass balance buoys were deployed as our assistance to the International Buoy Polar Program; we have received acknowledgements from the Alfred-Wegener Institute, Germany, and the University of Washington, Seattle. Biological net observations and trawling were also accomplished. Ice measurements and samplings were carried out from four ice stations.

In September 2003, the second CABOS mooring was recovered, and a third mooring was deployed in 1117 m of water in the southern Beaufort Sea (Figure 4). This mooring was deployed specifically to monitor the warm Atlantic water boundary current flowing around the perimeter of the Canada Basin. Its design was similar to that of the Mackenzie Canyon and Banks Island moorings along the main mooring line with an additional microcat CTD placed above the main flotation level, at a depth of about 35m. Our hope is that the mooring will give valuable information about Atlantic and halocline water transport, variability, and water-mass transformation mechanisms.

An example of the MMP record obtained in 2002 from the Canada Basin is shown in Figure 5. We were lucky to capture a passage of an eddy through the mooring location. This eddy produced a strong disturbance in the temperature, salinity, and velocity fields with classical doming of isopycnal surfaces and two strong maxima in the velocity distribution. This kind of record will help us to understand the complex nature of the processes occurring in the Arctic Ocean.

IARC/NABOS and AARI also continued a series of scientific projects that utilize historical information. As a results of this analysis, two papers have been published and one submitted to top oceanographic journals with acknowledgements to NABOS/CABOS. An EOS paper has also been published describing the program achievements and future plans; copies of the papers are attached. A web page has been developed and features the latest accomplishments of NABOS/CABOS (http://www.frontier.iarc.uaf.edu/NABOS/index.php). Mr. Robert Chadwell was hired by NABOS as a mooring technician. His numerous responsibilities include designing and building deep-sea moorings, participation in their deployment and recovery, and preliminary analysis of newly obtained information.

Year-2004-05 and beyond

In August-September 2004, a third NABOS cruise to the Eurasian Basin is planned, again using the Russian icebreaker "Kapitan Dranitsyn." We expect to retrieve the MMP moorings deployed in summer 2003 and to replace them with similar MMP moorings, initiating the planned multi-

Figure 2. NABOS-2003 observational area. Icebreaker track is shown by solid line. Crosses are locations of CTD casts, grey circle shows location of recovered and re-deployed mooring, black circle shows location of newly deployed mooring, triangles show locations of deployed ice buoys.

Figure 3. Pathway of the Russian icebreaker “Kapitan Dranitsyn” during the summer
2003 cruise.

Figure 4. Locations of CABOS moorings in the Canada Basin. (click on map for larger image)

Figure 5. Depth-time diagram of the MMP profiler record of water temperature (top), salinity (middle), and current speed (bottom) measured in the Canada Basin in 2002-03. Note the clear signature of eddy passing through the mooring location with domed isopycnal surfaces and increased speed.

year record at these locations in the Eurasian Basin. Two or three additional moorings will be added, forming the basis of the two NABOS cross-sections (Figure 1). One of these moorings is planned for deployment within the Russian EEZ. Attendant CTD, ice, meteorological, biological, and chemical observations in the same area of the Laptev Sea slope will also be made. Our plan for the CABOS Program includes recovery of our mooring from the Canada Basin and deployment of one or two additional moorings, depending on ship availability (Figure 1).

We plan to continue our analysis of available historical data, and hope to finalize our next joint U.S.-Russian publication on the Atlantic water long-term variability during the next year. Future plans for field work anticipate a gradual increase in the number of moorings, depending on funding. Our plans for 2004 and beyond are indeed significantly more complex than those of the 2002 pilot project and 2003 first year of NABOS, but the lessons learned from our first year of cooperation provide a solid foundation for future work. We will continue our efforts to develop a new agreement between the governments of the U.S. and the Russian Federation on cooperation in oceanographic research, in which NABOS appears as a specific project.

Acknowledgements

We wish to express our gratitude to the funding agencies NSF and Frontier. We are thankful to many people around the world working enthusiastically to make this complex program a reality. At UAF, we would like to thank particularly Debbie Moore, Dale Henderson, Stan Schwafel, Colleen Jones, and Kathy Glodowski, whose efforts were invaluable for the program.

LIST OF STATIONS

Station

date

time (GMT)

Latitude

Longitude

Depth

CTD

Rosette

Net

Trawl

MMP/Dep

MMP/Rec

Buoy

Ice St.

KD0103

01/09