Base de données de recherche des TNO

étiquettes: physical sciences, environmental monitoring, oceanography, sea ice, remote sensing

Objectif(s): To measure the upper ocean warming (0 - 60 m layer) that occurs as sea ice retreats in the Arctic Ocean during summer, and also the fall cooling.

Description du projet: The goal for this research project is to measure the upper ocean warming (0 - 60 m layer) that occurs as sea ice retreats in the Arctic Ocean during summer, and also the fall cooling. The surface layer (0-50 m) of the Arctic Ocean has in recent years experienced unprecedented summertime warming. The causes are still under investigation, but are undoubtedly related to extreme summer sea ice retreat, which allows more atmospheric heating and northward advection of warm sub-arctic waters. Warming surface waters in turn melt more sea ice (“ice-albedo feedback”) and delay fall ice growth. They also affect marine ecosystems, atmospheric boundary layer characteristics, and water mass formation. Presently, we can observe ocean surface temperatures by satellite, although these data need more validation and do not tell us about the vertically integrated heat content of the upper ocean. Hydrographic cruise data can measure sub-surface warming, but provide only a “snapshot” view of the warming at one time during summer. Ice-based buoys exist that can measure temperature profiles, but these are not optimized for observing the open sea. Thus the objective in this proposal is to fill this gap in the Arctic Observing Network measurement strategy, i.e., to measure the time history of summer warming and subsequent fall cooling of the seasonally open water areas of the Arctic Ocean. This research will focus on those areas with the greatest ice retreat, i.e., the northern Beaufort, Chukchi, East Siberian, and Laptev Seas. Prof. David Barber and his group will deploy 2 UpTempO buoys for Dr. Michael Steele. Each buoy consists of a surface float (2 feet in diameter) with an Iridium antenna and sea level pressure sensor. The float also contains electronics and alkaline batteries. Hanging down from the float is a 60 m long line with 12 thermistors at irregular depth levels (2.5 m, 5 m, etc down to 60 m). There is a terminal weight of about 20 lbs at the bottom. The buoys are shipped in a 2 foot x 2 foot x 2 foot double walled cardboard container, weighing less than 50 lbs. The buoy is deployed from the ship or a small boat by first lowering the terminal float into the ocean, then the string of thermistors, and finally the surface float. Data are recorded via satellite link (Iridium). The buoys will be deployed during Legs 2a or 3a of the cruise (see attached), in the deepest water possible. The hope and best calculations are that the buoys will drift westward into the deep southern Beaufort Sea, recording the summer warming and winter cooling of the upper ocean. Each buoy has batteries for 2 years of operation. Data will be made available in near real time to the international community via the CADIS web site. Canadian scientists aboard the Canadian coast guard ship Amundsen will deploy the buoys. This project is in close collaboration with similar work pursued by Professor David Barber and colleagues at the University of Manitoba. This research team will provide data and work together to produce scientific results, which will be communicated to local communities. The fieldwork for this study will be conducted from August 1, 2011 to August 15, 2011.