McPhee, M. McPhee Research Company,
Morison, J. Univ. of Washington Applied Physics Laboratory,

The Arctic is undergoing significant change. Over the past decade, the upper ocean, the motion of sea ice, and the atmospheric circulation have all shown marked deviation from climatalogical means. The boundary between eastern and western upper ocean halocline types has shifted from the Lomonosov Ridge to the Alpha and Mendeleyev ridges, implying a much greater influence of Atlantic Water in the Makarov Basin. In the eastern Arctic, Atlantic Water temperature has increased, and the strength of the cold halocline that isolates sea ice from the warm Atlantic Water has decreased. Patterns of atmospheric pressure and ice drift in the 1990s differ from climatology, with the main gyre axis shifted counterclockwise 40-60 degrees. Recent publications document a weakening of the polar anticyclone, and indicate that the atmospheric changes extend from the top of the atmosphere to the surface. During the 1997 SHEBA deployment, sea ice was much thinner than expected, with upper ocean salinity nearly 10% less than during the AIDJEX project in the same region two decades earlier. The most likely cause is excessive summer melting associated with increased insolation in open water (the albedo feedback effect). On a global scale, these changes may also be affecting other important processes, e.g., the virtual shutdown of deep convection in the Greenland Sea since the early 1990s.
Day: Tuesday, Feb. 2
Time: 02:30 - 02:45pm
Location: Eldorado Hotel
Code: SS15TU0215E