|COOKIES: By using this website you agree that we can place Google Analytics Cookies on your device for performance monitoring.|
Downwelling in Basins Subject to Buoyancy Loss
If you have a question about this talk, please contact Doris Allen.
Recent observational, theoretical, and modeling studies all suggest that the upper part of the downwelling limb of the thermohaline circulation is concentrated in strong currents subject to buoyancy loss near lateral boundaries. This is fundamentally different from the traditional view that downwelling takes place in regions of deep convection. Even when resolving the buoyant boundary currents, coarse resolution global circulation and climate models rely on parameterizations of poorly known turbulent mixing processes. In this study, the first direct measurements of downwelling occurring within a basin subject to buoyancy loss are obtained. Downwelling is observed near the basin’s vertical wall within the buoyant boundary current flowing cyclonically around the basin. Although the entire basin is cooled, downwelling is absent in the basin interior. Laboratory rotating experiments are conducted to explicitly resolve the turbulent mixing due to convective plumes, the baroclinic eddies generated by the boundary current, and identify where downwelling takes place. Hence, in the laboratory small vertical velocities can be measured more reliably than in many numerical calculations, while the measurement of these small vertical velocities is still a challenge for field experiments. Downwelling is observed to occur near the vertical wall within a boundary layer with a thickness that scales with the Rossby radius of deformation, consistent with the dynamical balance proposed by a previous numerical study. Hence, downwelling in the Labrador Sea and Lofoten Basin cyclonic boundary currents may be concentrated in a Rossby deformation thick boundary layer in regions with large eddy generation.
This talk is part of the Geophysical and Environmental Processes (DAMTP/BPI) series.
This talk is included in these lists:
Note that ex-directory lists are not shown.
Other listsNumber theory study group: Iwasawa theory DPMMS Lists Clinical ID talks
Other talksBiobanking 2016 Host cell ion channels as new anti-viral targets? Making, breaking and directing polarity during neural lumen formation and neurogenesis in the zebrafish embryo Emergent Syntax: a new (unifying) perspective Mechanisms for encoding integrated calcium signatures in plants Novel Methods for Determining the Evolution of Turbulence in the Surface Boundary Layer