ALTEX Arctic Cruise
October 7 - November 7, 2001
Tromso, Norway to the Arctic Circle
October 11, 2001: Day #5
Mike Pinto writes: The day started at 6:30 am with clear skies and the ocean as smooth as glass, 500 miles from the top of the world. Distant clouds on the horizon could have been mistaken for floating ice but no ice yet. Temperature outside was -6 degrees Celsius (21 degrees Farenheit) and water temperature a chilly 0 degrees Celsius. Today's work continued focused on troubleshooting and repairing several electrical shorts in the AUV caused by earlier seawater intrusion in the wiring. While this activity continued, Jim B. and Dr. Son Nghiem (JPL, NASA) took a two-hour flight in one of the Healy's HH65-A search and rescue helicopters to scout out solid ice for the next phase of the experiments. They returned just after noon, under a sky that almost looked like dusk.
Today's other task was to begin the CTD (conductivity, temperature, and depth) data survey utilizing an instrument used by oceanographers to collect sub-surface seawater samples. This work is headed-up by Dr Ned Cokelet from NOAA/PMEL.
The actual ALTEX experiment, to be conducted in 2003, involves mapping and tracking the warm water layer that enters the Arctic around the Svalbard region and runs along the edge of the Nansen Basin exchanging the heat of the warmer Atlantic into the Arctic Ocean. The experiment will help understand the transfer processes in this area and refine current understanding about climate change and effects on ice coverage. The CTD data collected on this cruise will help identify specific regions to map for the experiment and to verify the CTD data collected by the AUV sensors.
The ship's CTD rosette was attached to a line and consisted of a ring of 24 compartments that can collect seawater at different ocean depths by surface control. In addition, the rosette contained onboard sensors to measure real-time conductivity, temperature and depths. With this data oceanographers can characterize the physical properties of the sub-surface masses of water. The water samples will be used to accurately measure the salinity, oxygen and nitrate levels to further characterize the water at sampling depths ranging from 3000 meters to the surface. All of this is controlled, monitored, and logged from the science control area aft of the bridge.
As part of the CTD team, I was trained by Amy West to log data as the samples are collected and collect samples in bottles after the equipment is back on deck (in a nice warm enclosure - thank goodness). Amy had prepared the sample bottles prior to the casts and she later taught me the specific collection technique to ensure accurate chemical analysis back in the lab
The casts begun in the morning were planned to continue until noon the following day. As the equipment was lowered into the depths the computer graphically displayed the relatively warm water current (3 degrees C delta) just below the surface (100 to 500 meters) on each cast. As the equipment continued to lower, the temperature dropped until it reached a somewhat constant number.
Five casts were completed by early evening. I'm scheduled to relieve Amy at 1:00 am so I better get a few hours sleep.