HR: 14:10h
AN: OS32C-03    [PDF]
TI: Stochastic Forcing of the North Atlantic Wind-Driven Ocean Circulation
AU: * Chhak, K C
EM: chhak@colorado.edu
AF: Program in Atmospheric and Oceanic Sciences, and Cooperative Institute for Research in Environmental Sciences, University of Colorado Campus Box 311, Boulder, CO 80303-0311 United States
AU: Moore, A M
AF: Program in Atmospheric and Oceanic Sciences, and Cooperative Institute for Research in Environmental Sciences, University of Colorado Campus Box 311, Boulder, CO 80303-0311 United States
AU: Milliff, R F
AF: Colorado Research Associates (CoRA), 3380 Mitchell Lane, Boulder, CO 80301-5401 United States
AU: Branstator, G
AF: National Center for Atmospheric Research (NCAR), 1850 Table Mesa Drive, Boulder, CO 80305 United States
AU: Holland, W R
AF: National Center for Atmospheric Research (NCAR), 1850 Table Mesa Drive, Boulder, CO 80305 United States
AB: The magnitude of stochastic wind stress forcing due to atmospheric weather has been observed to be comparable in size to that of the seasonal cycle at mid-latitudes. Stochastic forcing is therefore likely to have a significant influence on the ocean circulation and climate system. In this work, the goal is to determine the effect of the stochastic component of the wind forcing on the North Atlantic ocean circulation. To this end, a quasi-geostrophic model of the North Atlantic was forced with stochastic wind stress curl data obtained from NCAR's Community Climate Model 3. The enstrophy dynamics in model experiments suggests that much of the stochastically induced variability in the ocean circulation occurs via the western boundary current. This localized response occurs even though the stochastic forcing occurs over most of the ocean basin. Using the ideas of generalized stability theory, we are able to conclude that this localized response is due to Rossby waves interacting with the mean flow in the western boundary. We also find, by looking at the model pseudospectra, that the non-normal nature of the model enhances the transient growth of perturbation enstrophy and helps maintain the stochastically induced variance that is produced in the western boundary region.
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 4504 Air/sea interactions (0312)
DE: 4532 General circulation
DE: 4599 General or miscellaneous
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting