by . An impediment to navigation, pressure ridges are also of climatological interest since they impact the mass, energy and momentum transfer budgets for the Arctic Ocean. the submerged volume of broken ice under a ridge, forced downwards by pressure, is termed an ice keel. Knowledge of ridge size and distribution is of interest because ridges present formidable obstacles to both surface and submarine transportation systems. Such ice is relatively weak in strength when newly formed, and is a navigational hazard not because of its strength, but rather because of the thickness. Pressure ridges occur mostly in newer ice because new ice is the most salty and flexible of the ice types. PRESSURE RIDGE SEA ICE SAMPLES . The presence of pressure ridges is thus very important for the development of sea ice dynamics. English: A pressure ridge (ice) is an ice formation typically found on large frozen lakes or sea ice during the winter. edge of one floe on top of edge of another floe Pressure ridges are one of the most dominant morphological features of the Arctic sea ice pack. Sea ice movement and deformation is driven by internal and external stresses on the ice. Thirty-six constant strain-rate uniaxial tension tests were performed on vertically oriented multi-year pressure ridge samples from the Beaufort Sea. Ridges and keels (hummocks and bummocks) in sea ice flows are important in sea ice research for both scientific and practical reasons. G.F.N. A MULTI-YEAR PRESSURE RIDGE 23 route seems to be the only possible solution. A long ridge of ice that has formed when two floes of thick ice have been squeezed together by wind or ocean currents, with the ice breaking into chunks that pile upward and also downward below the ice. The first ridges in winter were observed to build in the northeastern part of the Bothnian Bay in November. Individual pieces pile up to form rafts and eventually solidify (3 rd image). a line or wall of broken ice forced up by pressure. pressure ridge . The ice near the shore remains very stable and does not move from the shoreline. Cox and J.A. Sea ice has made the Northwest Passage impractical as a … May be fresh or weathered. Ridges and keels play important roles in both cases because they determine the external wind and current stresses via drag coefficients. Sea ice begins as thin sheets of smooth nilas in calm water (top) or disks of pancake ice in choppy water (2 nd image). Water begins at this point under the ice. Over time, large sheets of ice collide, forming thick pressure ridges along the margins (4 th image). Richter-Menge U.S. Army Cold Regions Research and Engineering Laboratory 72 Lyme Road Hanover, NH 03755 ABSTRACT . rafted ice . The forces required to form ridges are an important part of the rheological behavior of pack ice since the compressibility of the pack is determined, in part, by the formation of ridge structures. relatively small ice enclosed water area in the midst of pack ice other than a lead . The STOL-airplane landed on the fast-ice between the pressure ridges (right) and the island. Distribution, morphology and structure of sea ice pressure ridges in the Baltic Sea Paula Kankaanpää Department of Geography, University of Helsinki Abstract. Up to this point, the ice is anchored to the bottom of the lake. The pack-ice of the Arctic Ocean is pushed up at Cape Columbia, April 18, 1990. ice, depend mainly on the aerodynamic roughness of sea ice and pressure ridges, that is, on the undulations of the sea ice surface on a small scale, on the mean height, mean spacing and ridging intensity of pressure ridges on a large scale [Arya, 1973]. Where Does the Pressure Ridge Start? A pressure ridge usually starts a few hundred feet off the shoreline in what would be 2-3′ of water in the summer. The principal obstacle to the devel- opment of such a route is, of course, the highly variable and, at times, extremely formidable sea ice cover which has restricted the operation of surface ships to a few months each summer.
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