The Swedish icebreaker Oden as a research platform The Arctic Ocean Experiment 2001

1. The Swedish icebreaker Oden as a research platform The Arctic Ocean Experiment 2001 Meteorology The meteorology measurements were designed to both continuously monitor the state of the lower tro-posphere and to take more detailed measurements of important processes during interesting events. The monitoring was primarily achieved with a suite of remote sensing instruments: A Doppler cloud radar, a 915 MHz wind profiler, a scanning passive 5mm microwave radiometer and two sodar systems - one mono-static sodar for boundary-layer structure and a bipolar Doppler system for vertical wind speed profiles. These measurements, complemented by soundings, provided semi-continuous profiles of clouds, wind speed and direction, temperature and moisture through at least the lowest few kilometers for most of the two-month cruise. During a three-week ice drift, an 18-m mast was also erected on the ice, with surface-layer profile and turbulence instruments, while two Integrated Surface Flux Facility stations were deployed on remote locations on other ice floes. A tethered sounding system for profiles, turbulence and aerosols was also deployed near the ship. Additional measurements include radiation sensors and microbarographs. Atmospheric chemistry and aerosols Continuous measurements of atmospheric chemistry and aerosols were performed on Oden’s 4th deck. The air inlets on the port side of the laboratory containers are visible on the pictures below. A special problem was to avoid contamination from the ships local emissions; Oden had to be turned up-wind for all measure-ments. An air pollution sensor was attached to the inlet to facilitate automatic shut-down of all systems when sensing contamination. Air from the inlets was distributed to the laboratory containers with aerosol and atmospheric chemistry instruments, and a mass spectrometer for trace gas measurements. Aerosol filter packs were also analyzed with a ion chromatograph also located in one of the containers. Additional atmospheric chemistry and aerosol profile measurements were taken with the helicopter. The thetered sounding system was also frequently used for aerosol measurements and a few times to lift an inlet for the mass spectrometer. Related biological parameters were also sampled: Water samples at diff-erent depths, ice-core samples and the surface microfilm of the open water. The latter was sampled by a remote controlled small boat. Analyses of these were performed in the permanent foredeck laboratory. Michael Tjernström and Caroline Leck Department of Meteorology, Stockholm University SE-106 91 Stockholm, Sweden Corresponding author: michaelt@misu.su.se http://www.fysik.lu.se/eriksw/aoe2001/aoe2001.htm The science Air inlets Air inlets 4th deck atmospheric chemistry and aerosol laboratories S-Band cloud and precipitation Doppler radar The ice camp seen from Oden’s bridge Pump house formation, over local turbulent transport at scales from 100’s of meters to kilometers, to long-range transport at the basin scale. The logistic challanges mounting such an expe-riment are monumental. Already getting to the central Arctic presents a major problem. Once there, measurements on the ice require - in ad-dition to a stable ice floe - somewhere to live, to locate laboratories, power supply, and just moving about on the ice, transporting and in-stalling instruments, presents a problem. At the same time, the pristine conditions re-quire that chemistry measurements are pro-tected from any contamination from the ship. Utilizing the ice-breaker Oden as a research platform and a logistics base made this expe-riment possible. Arctic stratocumulus almost always warms the surface, and in summer the cloud cover is large. An important part of the energy balance is then governed by cloud microphysics. Due to the rela-tively low Cloud Condensation Nuclei (CCN) con-centration in the Arctic, clouds are less reflecti-ve here than at mid-latitudes. More abundant CCN could change the drop size distribution, cause an increase the cloud albedo and thus alter the radiation balance at the surface. Resolving the issues related to formation of low clouds in the Arctic necessitates experimental studies with an interdisciplinary approach: Me-teorology, atmospheric chemistry, aerosol che-mistry and physics, and marine biology, all played a role. Processes span a large spectrum of scales, from the micro-scale of aerosol and cloud 915 MHz wind profiler Doppler sodar Boundary-layer mast Gas storage Foredeck laboratory Fetch of the air inlets over the ice Tethered sonde winch Sodar antennas Inside view from container lab. Scanning passive 5mm microwave radiometer 5-level tempera- ture and wind speed profile Sonic anemometers Tethered soundings of aerosols and chemistry Radiation budget Arial photo of the the ice floe used for the ice drift experiment. Insert show the measurement site on the ice and Oden in its harbor. Setting up a remote ISFF station Inlet for aerosols and gases Aerosol inlet Aerosol rack Inside view from foredeck lab. Power stand Instrument platform Soundings were launched every six hour during research stations and the ice drift Where, when and how Tethered sounding, here using a small kite floe. An L-shaped harbor was cut into the ice to allow turning of the ship to face approximately into the wind at all times. Oden served as a measurement plat-form, logistics base for work on the ice and living quarter for the experimental staff (c:a 50) and the crew (c:a 15). Measurements were carried out onboard the ship, on nearby ice, neighboring ice floes and with a helicopter, utilizing both in situ instruments and remote sensing techniques. The Swedish Secretariat for Polar Research was instrumental in supplying access to Oden and also additional logistic support. The Arctic Ocean Experiment 2001 (AOE-2001) was a two-month atmospheric experiment on the Swedish icebreaker Oden. She is a diesel-powered, 108-m long, 24500-hp icebreaker built in Sweden in 1988, and is particularly effective in the Arctic, capable of continuously breaking 2-m thick ice at a speed of 3 kn. She was the first non-nuclear powered icebreaker to reach the North Pole in July 1991. The cruise track of the AOE-2001 is shown below. A major component of the experiment was a three-week ice drift, from 2 to 21 August 2001. During this time, Oden was moored to a drifting ~ 1.5 x 3 km ice Future plans A letter-of-intent for a new atmospheric experiment to the central Arctic, in the summer of 2007, has just been submitted to the Swedish Polar Research Board and planning is just beginning. Interested scientists can contact the authors for more information. Remote controlled boat for surface micro-layer sampling Approximate ice boundary 25 August