2.2 Does ocean bottom topography influence the Antarctic Circumpolar Wave?

Monday, 2 May 2011: 11:00 AM
Rooftop Ballroom (15th Floor) (Omni Parker House )
Nuncio Murukesh, National centre for Antarctic and Ocean Research, Vasco Da Gamma, Goa, India; and A. Luis and X. Yuan

Analysis of bandpass filtered sea-ice concentration, sea surface and air temperature revealed that the Antarctic Circumpolar Wave (ACW) terminates its eastward propagation at the western margins of the Indian Ocean sector of the southern Ocean. A deep ocean-bottom topography facilitates a topographic meandering of Antarctic circumpolar Current (ACC) that advects the ACW anomalies southward. The southward meandering of the ACC facilitates warming of the region east of 20°E by about 1ºC during winter, These processes interfered with the eastward propagating positive sea-ice anomalies, and reduced their strength. Warming of the ocean induced by topographic meandering leads to convection between 40°-60ºE in the atmosphere. Estimates of temperature advection in the atmosphere indicates that ACW propagates conspicuously in regions where vertical thermal advection is lower than horizontal thermal advection, as observed in the Weddell Sea. In the region between 40°-60E vertical/meridional advection of temperature was greater than the zonal advection. Thus in this region the atmospheric anomalies have a tendency to advect upward/southward, whereas the oceanic anomalies advects southward. This results in the decoupling of atmospheric and oceanic anomalies associated with the ACW and its termination.
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