PS97 Weekly Report No. 1 | 16 - 21 February 2016
At midnight between the 19-20th of February we finally had the get-go for the FS Polarstern PS97 Expedition. It was a long way to this very point. An advance group had arrived in Punta Arenas six days prior to aid in changing over containers from the previous Antarctic Expedition PS96 with our materials. Unfortunately the FS Polarstern could not access the Mardones container loading pier in Punta Arenas, as it was still being occupied by a delayed freight ship. We had to wait until access was given for the extensive freight loading operations.
On Monday the 15th, a core team of scientists could access the FS Polarstern, as it had received access to the loading pier. Everyone was in good spirits to commence with the preparations, when a low-pressure system led to the temporary closure of loading operations at Mardones Pier. On Tuesday the entire scientific delegation boarded the FS Polarstern with their personal belongings and freight loading continued in the afternoon. Another storm hit Punta Arenas, which once again interrupted freight loading. In the evening of February 18, all container loading had concluded successfully following several hours of good weather. During the wait, access to our scientific equipment was limited. Hence build-up of biological, oceanographic and geological laboratories could only be performed once all containers were successfully loaded onto FS Polarstern. From here we took 12 nautical miles to the Bunker-pier Cabo Negro to transfer 2500 m3 of marine diesel for our upcoming Drake Passage journey – this would take another 11 hours.
There are 44 crew as well as 52 scientists, meteorologists, technical staff and helicopter pilots. The scientific members belong to six working groups with research expertise in geology, oceanography, geodesy and biology. Scientific members come from Argentina, Chile, Germany, France, Netherlands, Peru, Switzerland and Spain, hence, we have a nice international mix of people. One Chilean and two Argentine scientists on board fulfill the role as official expedition observers, nominated by their home countries, as our work will take place in the 12 mile radius of the respective countries coastline.
The main emphasis of the PS97 expedition is to understand the palaeogeographical role of the Drake Passage during global climatic changes on glacial to interglacial cycles during the Quaternary Period (2.6 Myr). Today the Drake Passage is the most important geographic constriction which the Antarctic Circumpolar Current flows through and thus plays a crucial role in ocean circulation and global climate. Although numerous oceanographic studies during the past 25 years have taken place in this critical area of the southern Ocean, these short-term studies hinder assessment of the natural oceanographic variation of the Drake Passage. Of particular importance is the interrelationship between oceanographic and atmospheric processes within the southern westerly wind belt. Our main objective during the PS97 expedition is to increase our understanding of past changes in Drake Passage dynamics. Our goal is to provide deeper insight and understanding of the future evolution of the Antarctic circumpolar current and westerly wind belt behavior. Both parameters are critical in the quantification of storage and degassing of CO2 in the Southern Ocean.
During our eight week expedition we have additional complementary scientific programs on board, such as: obtaining high resolution palaeoclimate archives of southern Chile and the South Shetland Islands, further development of see ice reconstructions with biomarkers as well as constraining the glacial history of the southern Chilean West Fjords. Parallel to palaeoceanographic and palaeoclimatic work we will also perform physico-chemical and biological research. Key questions posed here, address trace element limitations for biological productivity and recycling and how global climate change impacts Antarctic microalgae assemblages.
Now, back to the weather. We were forced to learn that the Drake Passage and the southern tip of South America are among the windiest locations on Earth. Initial low-pressure systems, as mentioned above, delayed or halted our loading efforts in Punta Arenas. In addition we were also forced to change our cruise track. Following departure our meteorologists from the German weather service, Max Miller and Hartmut Sonnabend, projected wave heights of up to 8.5 meters in the south-eastern Pacific off southern Chile. With such wave heights scientific work is unthinkable and sea-sickness would have spread like wildfire. Hence, we decided to sail toward east through the Magellan Strait and along the coast of Tierra del Fuego. Although the storm was also projected to cover this area, it is sheltered by mainland southern South America. Hence waves of “only” 4-5 meters in height were projected. We hope to successfully perform our oceanographic and geological work in the northern margin of the Drake Passage between Isla de los Estados and Cape Horn during the next few days. This area should have been covered at a later stage of the expedition, however, in this rough area, namely the zone of the “furious fifties”, we have to adjust plans according to weather and sea conditions.
After fueling we finally made our way on February 20, at 1:12 in the morning. We were lucky to catch a short weather window, with drastically reduced wind speeds so that the Chilean pilots could aid our departure from Cabo Negro. The next morning everyone on board woke up to the smooth rolling of the ship. We will likely have to live with this and probably much stronger wave action for the upcoming weeks. A last glance of the Magellan Strait and Tierra del Fuego accompanied us in the morning whilst heading for the south-west Atlantic. With headwind we arrived at our first working station in the evening of February 20.
During the early morning hours of February 21, the first oceanographic work stations began. At two locations physical parameterization (CTD) and current velocities (L-ADCP) were measured and the Rosette was used to sample the water column. The goal of this work is to characterize the Subantarctic water masses entering the southern Atlantic after having passed through the Drake Passage. The relatively small depression between the Isla de los Estados and the easterly lying Burdwood Bank provides the first through-flow location for surface and intermediate water masses toward north.
Today, February 21, we are faced with wind speeds of 7-8 Bf and 3-5 meter waves. We are looking for the first geological sampling sites for the multi-corer and the gravity corer. We are optimistic to find 2-3 coring locations with good sedimentary cover and are planning to work late into the night. For tomorrow the next low-pressure system has been forecast and we expect a heavy storm to hit us.
The majority of the participants are doing well, however, some need to cope with sea-sickness. We will likely have to get used to that!
Chief Scientist PS97
Position: 54°45,51´S; 61°40,3´W (ca. 200 nm ENE Cape Hoorn)