SEMINAR: AOML Seminar - September 24, 2010 - 10:30 a.m - Selma Huisman , Ph.D. - “Asymmetry in the global ocean circulation”

["Aoml.Receptionist" <Aoml.Receptionist@noaa.gov>]

AOML Seminar

DATE:               Friday, September 24, 2010

TIME:                10:30 a.m. – refreshments at 10:15 a.m.

LOCATION:     AOML First-Floor Conference      Room

SPEAKER :       Selma Huisman , Ph.D.

Institute of Marine and Atmospheric Research Utrecht (IMAU), Utrecht University

TITLE :             “Asymmetry in the global ocean circulation”

Abstract:  The most striking feature of the global overturning circulation is its geographical asymmetry. While there is Deep Water formation in the North Atlantic, there is no similar process in the North Pacific. The reason lies in the salinity difference between the two basins; the water in the North Pacific is too fresh to induce strong convection events. When we consider the surface freshwater flux (E-P), we can see that precipitation over the Pacific and Atlantic are fairly similar. However, the Atlantic has a much higher evaporation, due to higher surface temperatures. These higher temperatures are a direct result from the presence of a vigorous meridional overturning circulation in the Atlantic. Therefore, this reasoning involves a circular argument.
In this seminar I will argue that multiple equilibria in the ocean circulation play a crucial role in setting this salinity difference between the Atlantic and Pacific, and therefore in the global ocean
circulation. Several process studies with idealized ocean models show that asymmetric solutions (like the present day ocean circulation) can be selected due to asymmetries in forcing and geometry. If we can understand this selection process, we can understand how the global meridional overturning circulation may react under changes in this forcing.