Woods Hole Oceanographic Institution
Cruise Planning Synopsis
|Dave Hebert: Chief Scientist, Principal Investigator|
GSO, University of Rhode Island 215 South Ferry Road Narragansett, RI USA 02882
+1 902 426 1216
Departure: Feb 27, 2011
Arrival: Apr 4, 2011
|northeast of Flemish Cap. off Newfoundland, Canada|
|Lat/Lon: 50° 0.0′ N / 43° 0.0′ W|
|Depth Range: 100 / 2000|
|Will the vessel be operating within 200 NM of a foreign country?||Canada|
|Are visas or special travel documents required?||no|
The cruise track shows the area (300 km x 300 km) of the high-resolution (HR) eddy survey. The actual location of the stations will be determine just before the cruise based on satellite altimeter data and on the transit to the first CTD station. The survey would consist of north/south transects separated by 60 km along which the velocity field, using the shipboard acoustic Doppler current profiler (ADCP) will be measured continuously to about 700 m depth. Every 50 km, a CTD cast to 1000 m will be done. Between CTD stations, an underway CTD system, operating in a tow-yo mode, will provide a CTD profile to 250 m at 10 kts every 10 minutes (3 km). XBTs will be used as backup to provide temperature profiles to 800 m halfway between normal CTD casts. These surveys will take 5.5 days each to complete.
Between the two HR surveys planned, a larger scale survey to map out the surrounding eddy field and fronts, the NAC from the south and the waters leaving the eddy formation region to the east. This large scale survey will allow us to detect whether previous eddies are located in the region. If so, we can determine their structure and whether it is consistent with our hypothesis of sinking or interacting with the continental shelf and producing cyclonic eddies. CTD casts will be undertaken every degree of latitude (~110 km) along the transects which are separated by approximately 80 km. This survey will take about 12 days to complete. Underway CTD casts and XBTs will be done between the CTD stations.
Time permitting, we will occupy some of the CTD stations on a repeated Canadian hydrographic line from St. John’s tp Flemish Cap. Also, as a favour to the Canadians (eg. NRCan), the multibeam will collected and provided to them. Someone from NRCan will discuss settings, etc. when the ship is in Halifax.
In addition to the above work, ARGO floats and surface drifters will be deployed through the survey region.
The Gulf Stream travels along the eastern seaboard of the United States and Canada
bringing warm water northwards. South of Newfoundland, the Gulf Stream separates
into two currents, one that moves around the Grand Banks and travels northward
until approximately 500N where it heads eastward across the North Atlantic. This
current is known as the North Atlantic Current (NAC). In this region where the NAC
turns eastward, eddies are generated on a regular basis. The mechanism for their
formation and their evolution is unknown. This National Science Foundation project
is to investigate these processes.
Our hypothetical conceptual dynamical model of the formation, growth and
separation of the NWC eddy would consist of the following processes:
(1) Gradual accumulation of kinetic energy in an anticyclonic loop east of Fleming
Cap related to the momentum imbalance in the NAC turning from northeast to
northwest along the continental slope and splitting into two branches.
(2) Shedding a warm-ÂÂÂÂÂA?core eddy after the recirculation loop increases to a size when
the beta-effect is able to provide substantial self-propagation.
(3) Either substantial heat loss from the ocean to the atmosphere resulting in the
sinking the eddy core followed by a capping of the eddy or the eddy interacts
with the shallow shelf and continental slope resulting in submesoscale cyclonic
eddies generation and enhanced decay of the anticyclonic eddy.
Satellite-based observations suggest that the life cycle for this process is
approximately 2.5 months and the eddies, while present year round, are dominate in
To address whether this model is realistic, we plan two ~30 day expeditions
separated by approximately 1 month. During each cruise, two high-ÂÂÂÂÂA?resolution
hydrographic surveys of the eddy region will conducted. Between the two surveys,
a larger scale, coarse resolution survey of the region will be undertaken
|Pre-cruise Planning Meeting: Visit WHOI|
|Meeting Notes: Will travel to WHOI week of Jan 17th.|
| Station 1|
Days: 1 hr
Latitude: 52° 0.0 N
Longitude: 40° 50.0 W
|Funding Agency: NSF|
|Grant or contract number: OCE 1027573|
Scientific Instrumentation for R/V Knorr
|Bathymetry System 12 kHz|
|Sippican XBT System (Mark 21)|
|Bathymetry System 3.5 kHz|
|Science Underway Seawater System|
|ADCP 75 kHz|
|911+ Rosette 24-position, 10-liter bottle Rosette with dual T/C sensors|
|SBE43 oxygen sensor|
|Wet Labs ECO-AFL fluorometer|
|Wet Labs C*Star transmissometer (660nm wavelength)|
Critical CTD Sensors
|Wind speed and direction|
|Short Wave Solar Radiation|
|Will you be using Long Base Line (LBL) navigation?||no|
|How many nets?||0|
|How many tansponders?||0|
|Will you be using Doppler/GPS navigation?||yes|
|CTD Winch with .322" Electro-mechanical wire|
Standard Oceanographic Cables
Specialized Deck Equipment
Over the Side Equipment
|Will you be bringing any equipment (winches, blocks, etc.) that lowers instruments over the side?||yes|
Underway CTD (uCTD) system (Ocean Sciences)
This will deploy off stern / fantail. Science will bring all parts and mounts.
Additional Cruise Items/Activities
|Portable Air Compressors:||no|
|Small Boat Operations:||no|
|SCUBA Diving Operations:||no|
|Will hazardous material be utilized?||no|
|Describe deployment method and quantity:|
|Is night time work anticipated on this cruise?||yes|
|Specialized tech support (Seabeam, coring, other):|
Seabeam used for tech training, etc.
|Other required equipment and special needs:|
Deck mounted XBT launcher
Checklist & Notes
|U.S. Customs Form:||yes|
|Date Submitted:||Nov 27, 2010|
Master R/V KNORR
Master, R/V Knorr
Phone: (902) 468-6544Note: Agent and WHOI contacts should be copied on all communications. It is requested that shipment information of any equipment be communicated to the Agent and to WHOI contacts.
|4455's for gear loaded at WHOI Jan 20, 2011.|
|Isotope Use Approval:||no|
|Some items loaded on Knorr Jan 20 2011. |
Rest loaded in Halifax.