Friday, October 19 – Late today we got our first Radar satellite image, which shows that the situation has worsened. Three days ago the band of pack ice was a narrow finger that centered on Palmer Station. Since then continual southwesterly winds have moved up to the north a tremendous amount of loose pack ice which has now grown into a bolus of tight pack ice that threatens to envelope the entire southern perimeter of Anvers Island, with Palmer Station in the center. On this image the clouds do not show up because it is radar reflectivity. Black or dark grey is open water, blue tinge is glacier ice or bedrock, and white is sea ice, both pack which is moving and fast ice which is frozen to the land perimeter. In fact the local pack ice near us in Arthur Harbour is starting to form fast to the shore, with continued subfreezing temperatures and occasional snow. Though today was clear. We are waiting for Palmer personnel to finish the set up of their labs and transition, when that accelerated program is completed (Sunday? AM) we will depart to get out of the ice (if we can) and do some science in the time that remains to LMG12-11.
So it seems that the science team onboard the Laurence M. Gould (LMG) has run into a few small bumps along the road to collecting data. Due to the amount of pack ice around Anvers Island, where Palmer Station is located, the research vessel has been unable to make the trip to any of our sites of interest. The tough decision was made last night to return to Palmer Station to conserve fuel and wait for strong winds to blow some of the ice out and allow the LMG to make it to open water. Based on recent years’ records, this amount of pack ice is an unusual occurrence for this season and is somewhat surprising considering the warming trend along the Antarctic Peninsula.
One thing to consider: rising temperatures can cause more freshwater to enter the ocean in the form of calved icebergs that melt as they drift out to sea. More freshwater in the ocean can raise the freezing temperature of seawater, which is normally around -1.8˚C. This explains why sea ice can reach such an unusually vast area even as the peninsula’s climate is warming. Also, sea ice is thicker and forms more readily to the south where temperatures are slightly colder. Thus, when the winds blow from the south and west, sea ice travels to the north and to the east. The sea ice then becomes trapped against the Palmer Archipelago, whose southernmost sizable island is Anvers. Furthermore, Palmer Station is located on the southern coast of Anvers Island. Recent wind patterns have blown the ice right into our path, clogging up the southern reaches of the Gerlache Strait and the Bismarck Strait.
Three weeks ago, Arthur Harbor and Anvers Island were bathed in open waters. In fact, the average temperature for the month of September at Palmer Station is higher than the past week’s average temperature; today it was around -11˚C, and yesterday it was -25 ˚C with wind chill. Indeed, we are witnessing winter sea ice conditions in the Bellingshausen Sea when the ice extent is supposed to be dissipating.
However, we have not let this setback prevent us from being as productive as possible while we wait for strong winds to clear out the ice. Yesterday we started in on our 12 hour shifts; this scheduling allows us to be doing science around the clock.
Today has been a big learning day in our trip. Thinking about and understanding the meteorological dynamics of the area that we are working in, including the development and movement of pack ice and fast ice, is important for background knowledge of the research that we’re doing. Overall, it’s been another successful day, and we are looking forward to continuing our work and learning even more about this exciting area of the world!
Throughout the day we continuously tracked our position by recording coordinates in a log book, and plotting the points, so as to be able to refer to our current position on a map whenever necessary. During the day shift, Deanna Nappi ’15 and Katy Smith ’13 worked with geochemist and Tulane University professor Brad Rosenheim to filter water samples that were collected at King George Island several days ago. By analyzing the water samples, Brad hopes to be able to date the sediment surrounding the island. After the filtering was complete, we worked to thoroughly clean all 3 of the labs that we will be using on the ship, so that when we collect samples, all of the instruments and spaces that we need to work with will be ready.
The LMG has finally docked at Palmer Station on Anvers Island. Palmer Station is one of the USAP’s main Antarctic bases in addition to the final destination for many other scientists onboard the LMG. Some will stay on station for up to six months conducting research in state-of-the-art labs. The station’s proximity to a glacier and the ocean (Arthur Harbor) make it an ideal place to take samples for geological, oceanographic and biological/ecological research. It is a picturesque location, but getting there was difficult due to the sea ice state.
I am told that in September, Arthur Harbor was open water, free of ice. This was not the case during LMG cruise 12-11. What started out as pancake icePancake ice is newly frozen seawater with a circular shape up to 3 meters across. and brash iceBrash ice is an accumulation of sea ice and glacial ice made up of frozen particles not more than 2 meters across. fields in the Gerlache Strait quickly turned to pack ice as the ship plugged along at its WSW heading. Although this winter was colder than the decadal average in the Western Antarctic Peninsula, wind patterns are the main reason for fast ice in the southern Gerlache during this October. Several low pressure systems swept across the region before we arrived, each bearing westerly winds. This forces the sea ice up against the southern and western coasts of Anvers Island, blocking the southern Gerlache Strait in turn. It was remarkable to see the sea ice pressure change while out shoveling the aft deck; the path the ship cut through the ice began closing up more and more quickly behind us. This is a result of increased ice pressure. Our captain did an excellent job navigating us through the pack ice especially considering the LMG is an ice reinforced vessel rather than an icebreaker.
Once at the station, we got off the ship and explored. We perused the Palmer Station store and purchased some candy and memorabilia. After dinner, Amelia Shevenell gave a 45-minute talk about her paleoceanographic research with extremophilic ArchaeaExtremophilic Archaea are microscopic organisms that inhabit extreme living conditions such as the cold, brine rich liquid pockets in the pore matrix of sea ice. that live in sea ice. The talk centered on a cutting-edge sea surface paleotemperature proxy called TEX86. This technique for constraining paleotemperature works on the idea that these Archaea change their lipid membrane structures in response to minute changes in sea surface temperature. If Amelia can sample enough Archaea in water samples during LMG 12-11, it will greatly supplement her research, help develop the TEX86 technique and lend further credibility to a relatively new scientific practice that was developed in 2002.
After Amelia’s talk, we gathered in the lounge, and Gene introduced us to the lab manager at Palmer and came up with a fantastic outreach initiative for the LARISSA program. Normally, when we take a sediment core, some of the extraneous sediment is thrown overboard. Rather than waste perfectly good examples of the work that is being conducted in the Southern Ocean both with the International Ocean Drilling Project (IODP) and LARISSA, we will donate these extra cores for Palmer Station to put on display. Every summer, thousands of tourists flock to Palmer Station and the Antarctic on cruise ships. We would like these visitors to see an actual sediment core with the hope that it will spark the public’s curiosity about our work. Meanwhile, the six- meter piston core is rigged and ready to go for tomorrow!
Today was the first day of intense data collection for the LMG 12-11 science crew! The morning hours were spent in transit through the Bransfield Strait where strong head winds and patches of brash ice kept the ship’s speed at a minimum. Since our last post, we actually experienced rougher conditions than the infamous Drake Passage. So rough that we missed the deadline for maintenance at Duthier’s Point which we will revisit after our first Palmer Station port call tomorrow.
The seas calmed as we entered the Croker Passage in the northern reaches of the Gerlache Strait. Around 14:00, we passed Two Hummock Island on the port side. Clear skies and calm water offered a spectacular view of the forbidding rocky and glaciated terrain.
Calm water also meant that conditions were ideal to set up our jumbo piston core lab and filter water samples for Colgate Professor Amy Leventer. While Katy and Deanna filtered the samples for phytplankton, Amelia, Brad and I (Garrett) used charts of the Gerlache Strait to provide waypoint coordinates to the bridge for our seismic line survey.
Meanwhile, the ship’s electric technicians and Gene saw to it that the Knudsen 3.5 seismic sensor was running properly in anticipation of our data collection after dinner. Gene also pointed out a glacier with meltwater conduits glistening in the sun at high elevation that disappeared as the meltwater percolated into crevasses and refroze inside the glacier. This kind of melting was not observed in this region two decades ago and is visual evidence of the rapid warming the West Antarctic Peninsula is undergoing.
Now that the scientific portion of the cruise is underway, we will rotate a member of the crew on watch to plot the LMG’s course and note ice conditions, sampling activity and writing down other noteworthy comments. After our first port call at Palmer Station, we will be split into a day-shift and night-shift so we can conduct round-the-clock science.
The whole team spent the after-dinner hours double-checking our waypoint coordinates and running the seismic survey. Our goal is to map the seafloor sediment in order to pinpoint an ideal coring site. Overall, we hope to use the seismic data to pinpoint a core site near the previous grounding line of an ice shelf that has retreated since the Last Glacial Maximum (LGM). The Last Glacial Maximum is a period of Earth's climate history (~19,000 to 25,000 years ago) when vast ice caps and ice sheets were at their maximum extent.
The team watched our seismic data collect as the ship plugged along at fewer than 6.0 knots. We learned a lot about how to interpret seismic data and how to note features including contourites, gas deposits and acoustic basement reflectors. By 22:15, the seismic survey was complete.
We were able to pick out several sites where the sediment is compacted enough to sample to depths deposited before the LGM. Even though Day 1 of science didn’t go as originally planned, it was a great success! Conditions are always changing down here, and it is crucial to know when to revert to Plan B.