There is so much planning that goes into making these research cruises a reality. Multiple conference calls, pre-cruise meetings, travel and lodging logistics, coring and site survey selection- all of these things spread over years. All that planning gets us on the ship … and then we have to adjust many well-laid ideas to suit the environment. Amelia tells us that as a PI (Principal Investigator), it’s not enough to have a Plan B; you have to have Plans A through Z.
Weather and ice conditions change so fast down here, so all the PIs need to be flexible with their own sampling strategies as well as accommodate each others’ scientific objectives. That means when we finally get into the ice, plans change; the decisions that dictate those plans are carefully weighed and executed. Going into this cruise, I knew there must be a whole list of reasons for choosing a core site. Now, 8 days in, I am finding out just how many factors contribute to our PIs’ decision and I am astounded at their combined knowledge.
First off, we need to be able to get to the site. Seems like a no-brainer, but like I said, conditions change so fast on Antarctica and in the surrounding Southern Ocean that a proposed core site that may have been ice free two days ago might be covered by ice today. Another factor our senior scientists need to consider is transit time and coring time. For example a transit time between Site 1 and Site 2 could take 4 hours, or it take 10 hours; this depends on the ice. Moreover, the entire coring processes (piecing together a 24-meter core liner, rigging the A-frame, taking the core and stowing the core, etc.) takes about 16 hours. That’s just short of a day and a half if everything goes smoothly.
Therefore, if one site holds higher priority over another (maybe the scientific objective is more important), then we may have to ignore that site to core another area along the shelf. One problem that is unique to the marine geology group is the quality of the core. Even if we have a site that is ice-free, conveniently located near a geophysics/CTD waypoint, and we have extra time to deploy, that site may not have the sequence of sediment that we want to study. The record may be too short, have too low a resolution, be discontinuous, etc.
This is a situation we are actually dealing with. A few days ago, the senior researchers decided that we would head to the Mertz Trough first because the sea ice had opened up. The geophysicists needed to take some seismic lines in this area, and if we had gone west to Totten glacier first, the ice might have moved in and the geophysics group would have lost their chance. But, the marine geology and physical oceanography group have placed a higher priority on the margin just offshore of Totten Glacier (we will be collecting all new data there), so we will only stay at Mertz Trough for a short time before sailing to Totten and spending most of our research days there.
Learning the ins and outs of choosing core sites, seismic lines, and CTD casts has given me a new level of respect for the PIs who make the hard calls. They sleep less, worry more, and yet still have time to teach their students. The Palmer is quickly becoming one of my favorite classrooms!