27 August 2015 Updates from the Drift Buoys

Cruise Day 19

Speed 0 knots (kts) (on station)
Course n/a
Location Makarov Basin, approx. 375nm S. of the North Pole (we are now closer to the pole than to the nearest land, Henrietta Island.)
Depth 2853 m

GO DEEPER DISCUSSION: (see previous journal for the questions.)

The pumps are operated at depths also sampled by the GEOTRACES rosette so that the data sets both generate can be directly compared and correlated to each other. For example, the transmissometer on the GEOTRACES rosette might indicate a water level with quite a bit of suspended particles in it and a high amount of chlorophyll fluorescence. This would point to an abundance of phytoplankton, which a pump filter could capture for more study if it was deployed at the same depth. So once we begin a station and establish target sampling depths, all of the successive sampling operations will aim for the same depths throughout the station whenever possible.

TODAYS JOURNAL:

We had another good run through extensive ice all night and this morning, reaching our next full sampling station at about noon today. The ice we have been in for the last few days has been classified as first-year ice (meaning it formed in one winter) at 8/10 to 10/10 coverage. This ice has been softened by the summer melt season, and even though my untrained eye would rate much of it at a meter or so thick, the Healy has been chugging through faster than expected. Gaps in the first-year ice have recently frozen over for the most part, with a few centimeters of dark ice covering almost all of the increasingly rare leads. The only open water is from the ships breaking efforts, or from very recently opened leads. Pressure ridges and blocks pushed up from the collision of white wind-driven floes, lazuli frozen melt ponds on the ice surface, and interspersed nearly black frozen leads create an interesting and dynamic surface, far from flat and uniform. With the help of satellite imagery to look ahead, it appears that we are about to enter multi-year ice, which grows over several winters and so is thicker. I expect that the ship will have to work harder and will make slower time through the ice as we leave this station.

Now that were in nearly complete ice coverage, the ship has to do a bit more work to prepare an area for sampling. Today we found an opening about the size of a football field that was acceptably close to our intended station coordinates. It was covered in new ice, but with a little crunching around and sweeping the broken bits back with propeller wash a suitable area of clear water was prepared. Coast Guard crew members armed with long, spike-tipped poles work thought sampling casts to fend off large blocks of ice that drift into the sampling area, but a mix of slushy ice and smaller blocks sometimes accumulates anyway. Today when we brought the GEOTRACES rosette back aboard we strained out some sea ice pieces about the size of bricks atop the frame. They were kind of neat to check out and slide around the deck a little before plonking them back into the ocean.

I earlier wrote about a few different drift buoys that we launched on our way up to the ice. Researchers working on both types were kind enough to email me with further information about their buoys. I talked about the first type, called UpTempO, on August 18 (Marginal Ice Zone.) We launched another on August 19. Heres an update on the UpTempO buoys from Kristina Colburn at the University of Washington:

The UpTempO buoys profile the top 25 to 60m of the marginal ice zone. We place the 25m in the more shallow water like the Chukchi and the 60m in the deeper areas. We are looking to see how heat gets transferred in the upper ocean layers both from radiation as the ice retreats and from the Pacific layer pushing in through the Chukchi. We have been seeing some interesting warming we cant explain with some of our buoys in the eastern side of Alaska around the 145W line as well. It was the hot topic of conversation in our State of the BuoyA float moored in water or ice to mark a location, warn of danger, or indicate a navigational channel. Meeting this morning.

The buoys you deployed are a new design so they are prototype buoys that are taking their first real trip to sea. Unfortunately we are still seeing issues with both buoys now. We are working at trying to figure out what is happening to cause the thermistors and pressure sensors to freeze up and only report a certain value repeatedly for extended periods of time. We are getting periodic readings that are real. Fortunately we have the buoy that I was unable to deploy off the Ukpik so we may be sending it back to PG to use for testing. Would have been fabulous if it had worked 100% on the first try but that is the joy of research and development. Sometimes you have to stumble over some hurdles before you find the right long term engineering solution. In fact most times that is the case. Failure is not a bad thing. As Edison said, he did not fail 100 times trying to make the light bulb, he found out 100 ways how not to make one :). In my opinion this is one of the most important things kids can learn about the world of cutting edge science. Not every experiment works, and that is ok because you learn from every experiment whether it was successful or not. -Kristina

I also journaled about a yellow float buoy on August 22 (Yellow Submarine). Andrey Shcherbina, also from the University of Washington, sent along some helpful information to clarify how the buoy works. This is from a flyer describing the prototype:

Improved understanding and prediction of Arctic change requires detailed, widespread and continuous information on the thickness and composition of the ice and the properties of the underlying ocean. We envision a fleet of underwater vehicles complementing existing satellite observations and aim to overcome the technological barriers to their operation. The Under-Ice float funded by Paul G. Allen Family Foundation and deployed August 22, 2015 from Healy is a first step towards this goal.

Under-Ice float is a new underwater platform that will continuously observe physical, chemical and biological properties of sea ice and of the upper ocean from below the ice. The float will drift beneath the ice, profiling to as deep as 200 m, and control its depth by varying its buoyancy in response to measurements of pressure and distance to the ice measured by an upward-looking sonar altimeter. It will seek natural openings (leads) in the ice, briefly surfacing to obtain a GPSA Global Positioning System (GPS) is a satellite-based navigation system used to track the location or position of objects on the Earth’s surface. fix, send data and receive commands.

The float will measure ice thickness from the upward-looking sonar and a pressure sensor. It will measure ice properties from the intensity and spectrum of the light transmitted through the ice. The intensity of the light will be increased by thin ice, leads and melt ponds, and decreased by thick ice and snow covered ice. The color of the light will be changed by the snow, drained thick ice, flooded thin ice and algae, varying with ice properties much as it does between coastal green waters, open ocean blue waters and stormy white waters. The float measurements of temperature and salinity will monitor the heating of the upper ocean and measurements of light and chlorophyll will quantify changes in algal biomass both in the ice and in the ocean. A camera will take pictures of the underside of the ice, which will assist in interpreting the light and ice thickness data and can be expected to return valuable images of ice algae masses, small crustaceans, fish and larger marine animals, thus describing the under-ice ecosystem on a scale not possible with other approaches.

I asked Andrey how often the float surfaces, and he replied:

Right now it checks the surface conditions almost constantly and attempts to surface as soon as it sees open water. The problem is that it is difficult to distinguish between the glassy-calm water and thin ice. In these uncertain cases, the float errs on the side of caution and does not attempt to surface. So far we've had 4 surfacings, about once a day. We cannot predict when it surfaces next - and even if it surfaces again at all. But when it does, we get a Twitter message (#mlf2_80), so I keep my phone by my bed.

I have to admit I think it is a good day for science when an autonomous Arctic under-ice float buoy checks in to home base by Twitter!

GO DEEPER!

On the sea ice concentration update, the boundaries between ice zones A, B, and C are estimated. Why cant these areas always be mapped precisely?

Aloft Con web cam updated every hour

Healy Track

That's all for now. Best- Bill