Weekly Reports Polarstern
The Expedition PS113 Punta Arenas - Bremerhaven
The cruise leg PS113 coincides with the return voyage of Polarstern after finishing the Antarctic research season 2017/18. PS113 will begin 07 May 2018 in Punta Arenas, Chile, and end 11 June 2018 in Bremerhaven. An intermediate port call at Las Palmas, Canary Islands, is scheduled for 03 June for the exchange of personnel. Most of the time (ca. 9/10) allocated to PS113 will be used simply for transiting between Punta Arenas and Bremerhaven at an economically reasonable steaming speed of Polarstern.
The ship time available for scientific station work hence is very limited. Emphasis will thus be laid on research work that can be conducted en route along the transit course. This encompasses the main scientific project to be conducted during PS113, the commissioning of a new measuring system, the Triaxus towed ocean profiler of the AWI (topAWI), for which purpose Polarstern has to steam at a lower than normal transit speed.
This new towed system will allow measuring simultaneously with high temporal and spatial coverage and resolution in a quasi-synoptic manner many physical, chemical and biological variables that are relevant to identify the processes, which control phytoplankton photosynthesis and primary production, hence the uptake of CO2. Primary production also forms the basis of the marine food webs and ecosystems, which yield living resources.
Commissioning of topAWI will for inter-calibration purposes be accompanied by measurements made with proven techniques, such as hydrographic stations enhanced by vertical profiling of ocean optical properties. The latter is also aimed at the validation of ocean colour satellite sensors hence at improved remote sensing of phytoplankton concentrations. Samples taken for plankton genomics will allow for an assessment of meridional differences in plankton species diversity, which are expected to occur along with the crossing of different climatic zones during the transit. Recordings of surface waves and currents made by the WaMos-Radar will be compared with the acoustically measured current shears from topAWI.
Changes in atmospheric properties and processes underway from the southern hemisphere, which is less perturbed by human activities, and the more disturbed northern hemisphere will be revealed using advanced lidar systems and sun-photometers. Deepest down at the seafloor and in the sediments, bathymetric mapping and sub-bottom profiling will be conducted using various sonar systems installed on Polarstern.
Last but not least, fish caught before in Antarctic waters will be held live in aquaria, attended and transported to the AWI for extended physiological investigations.