2008-08-15
0825 AKDT
We are coming off of night watch in a mild drizzle this morning, about 34 degrees at 0800. In the last 24 hours we successfully retrieved both of Ethan’s buoys. He is exhausted from the grueling physical work of snagging the buoys, with the help of the Coast Guard crew, on rough seas and 30-odd hours of no sleep. In his eagerness, he has already identified the songs of Beluga whales on a first crack at the data the buoys recorded. If we are lucky, he will be able to play the recordings for us soon. He started the recording process two years ago, first dropping the buoys as the Healy headed out on other science missions. He’s retrieved and re-deployed the pair on Healy missions in each of the two subsequent years by sending a radio signal from ship to ocean depths to call the buoys back to the surface. Being underwater they are not subject to the winter ice and can give a slice of the larger picture of behavioral patterns of various marine mammals throughout the years he records.
The other big project was running a “patch” test to make sure that the sonar equipment on the bottom of the ship is properly calibrated before we begin the actual mapping of the continental shelf.
Part of our track is above, the red line. The large ice floe to the northwest is the biggest one we've seen so far, some 30 miles long. The other colored bands are sonar swaths taken by the Healy on earlier cruises.
The patch testing involves some eight hours of ship time (which is not cheap – more on the costs and logistics of running such a science ship in one of my later entries). The process ensures that the remaining 520+ hours we have – most of which we can use for mapping – will produce the most accurate data possible. In those eight hours we run four tracks – the first about eight miles long over a part of the ocean floor that we think is as flat as possible, and the second a return trip over the exact same path, to test for “roll”. That exact track replication is made possible by (almost) state of the art mapping and positioning technology. If the two tracks show different characteristics indicating that the sonar is not recording properly, adjustments can be made. The same process is done on as steep a section of continental slope as possible to test for pitch and, again, adjust the sonar equipment if necessary.
The patch testing involves some eight hours of ship time (which is not cheap – more on the costs and logistics of running such a science ship in one of my later entries). The process ensures that the remaining 520+ hours we have – most of which we can use for mapping – will produce the most accurate data possible. In those eight hours we run four tracks – the first about eight miles long over a part of the ocean floor that we think is as flat as possible, and the second a return trip over the exact same path, to test for “roll”. That exact track replication is made possible by (almost) state of the art mapping and positioning technology. If the two tracks show different characteristics indicating that the sonar is not recording properly, adjustments can be made. The same process is done on as steep a section of continental slope as possible to test for pitch and, again, adjust the sonar equipment if necessary.
Understanding how an entire data set can be thrown off by minor mal-adjustments of pitch and roll lets me see how varying quality data can affect the final submission a state makes to the Commission on the Limits of the Continental Shelf. The quality of the submission in turn affects the extent of each claim.
The first of our nightly “Science Talks” brought home this point as well. Larry Mayer, our Chief Scientist, provided a geologist’s overview of Article 76 – the continental shelf mapping provision in the Law of the Sea Convention that is the basis for our primary work on this cruise. Larry directs the University of New Hampshire's Center for Coastal and Ocean Mapping (CCOM). The scientists at CCOM have developed truly amazing images of the sea bottom
that will help establish, with greater clarity than earlier techniques allowed, where the foot of the US continental slope off of Alaska might meet the ocean floor - a critical measurement under Article 76 for asserting continental shelf extension. Simply put, exceptional data collection and processing into visual images allows states to offer evidence of an extended continental shelf that covers a larger area than would be the case if they relied on data (and technologies) available at the time the treaty was drafted. Although the technology, because of the scientists who design and apply it, provides remarkable information about the continental shelf, it cannot overcome the basic problem that brought me here: in Article 76 lawyers defined the continental shelf in terms that have almost nothing to do with how geologists define it. The situation is made even more uncertain by the fact that both law and geology are disciplines where the most skilled interpretations of the raw materials (be it statutes or sonar readings) usually carry the day. As Larry phrases it, Article 76 “takes all of the ambiguity of science and mixes it with the ambiguity of law.” I am eager to learn more about the implications of this for lawyers and scientists.
