Watermass Transformation in Marginal Seas
Waters formed at high latitudes have distinct water mass characteristics that can be traced throughout the worlds oceans. This water mass transformation and transport is a fundamental component of the oceanic thermohaline circulation and plays an important role in the global climate system. I am interested in several aspects of how these waters are formed, where they sink, and how they are transported away from their formation regions. I am also interested in how the thermohaline circulation interacts with the wind-driven circulation, both at mid-latitudes and at high latitudes.
I have found that the dominant component of the downwelling limb of the thermohaline circulation takes place very close to lateral boundaries and steep topography. I have been using analytic models, simple scaling ideas, and general circulation modelling studies to understand and quantify the amplitude of boundary sinking and demonstrate its importance relative to large-scale interior downwelling and eddy-driven downwelling in a subpolar gyre.
This work has been generously supported through grants from the National Science Foundation and the Office of Naval Research:
Publications on this subject:
Spall, M. A., 2012. Influences of precipitation on water mass transformation and deep convection. J. Phys. Oceanogr., 42, 1684-1700
Vage, K., R. S. Pickart, M. A. Spall, H. Valdimarsson, S. Jonsson, D. J. Torres, S. Osterhus, T. Eldevik, 2011. Significant role of the North Icelandic Jet in the formation of Denmark Strait overflow water. Nature Geosci., doi:10.1030/NGEO1234
Spall, M. A., 2011. On the role of eddies and surface forcing in the heat transport and overturning circulation in marginals seas. J. Clim., 24, 4844-4858
Spall, M. A., 2010. Dynamics of downwelling in an eddy-resolving convective basin. J. Phys. Oceanogr., 40,2341-2347
Spall, M. A., 2010. Non-local topographic influences on deep convection: An idealized model for the Nordic Seas. Ocean Model., 32, 72-85, doi:10.1016/j.ocemod.2009.10.009
Spall, M. A., 2008. Buoyancy-forced downwelling in boundary currents. J. Phys. Oceanogr., 38, 2704-2721
Spall, M. A., 2008. Low-frequency interaction between horizontal and overturning gyres in the ocean. Geophys. Res. Lett., 35, L18614, doi:10.1029/2008GL035206
Pickart, R. S. and M. A. Spall, 2007. Impact of Labrador Sea convection on the North Atlantic meridional overturning circulation. J. Phys. Oceanogr. 37, 2207-2227.
Spall, M. A., 2007. Circulation and water mass transformation in a model of the Chukchi Sea. J. Geophys. Res. ., 112, C0525
Pedlosky, J. and M. A. Spall, 2005. Boundary intensification of vertical velocity in a beta-plane basin. J. Phys. Oceanogr. 35, 2487-2500
Spall, M.A., 2005. Buoyancy forced circulations in shallow marginal seas. J. Mar. Res. 63, 729-752.
Spall, M. A., 2004. Boundary currents and water mass transformation in marginal seas. J. Phys. Oceanogr., 34, 1197-1213
Katsman, C., M. A. Spall, and R. S. Pickart, 2004. Boundary current eddies and their role in the restratification of the Labrador Sea. J. Phys. Oceanogr., 34, 1967-1983
Pickart, R. S., M. A. Spall, M. H. Ribergaard, G. W. K. Moore, and R. F. Milliff, 2003. Deep convection in the Irminger Sea forced by the Greenland tip jet. Nature, 424,152-156
Spall, Michael A., R. S. Pickart, 2003. Wind-driven recirculations and exchange in the Labrador and Irminger Seas. J. Phys. Oceanogr., 33,1829-1845
Spall, Michael A., 2003. On the thermohaline circulation in flat bottom marginal seas. J. Mar. Res., 61, 1-25
Spall, Michael A., 2002. Wind- and buoyancy-forced upper ocean circulation in two-strait marginal seas with application to the Japan / East Sea. J. Geophys. Res., 107(C1), 6.1-6.12
Spall, Michael A., R. S. Pickart, 2001. Where does dense water sink? A subpolar gyre example. J. Phys. Oceanogr., 31(3), 810-825
Joyce, Terrence M., Clara Deser and Michael A. Spall, 2000. On the relation between decadal variability of Subtropical Mode Water and the North Atlantic Oscillation. J. Clim., 13(14), 2550-2569
Spall, Michael A., 1999. A simple model of the large scale circulation of Mediterranean water and Labrador Sea water. Deep Sea Res., II, 46, 181-204.
Spall, Michael A., and James F. Price, 1998. Mesoscale variability in Denmark Strait: the PV outflow hypothesis. J. Phys. Oceanogr., 28(8), 1598-1623.
Pickart, Robert S., Michael A. Spall and J. R. N. Lazier, 1997. Mid-depth ventilation in the western boundary current system of the subpolar gyre. Deep-Sea Res., 44(6), 1025-1054