John Marshall

Cecil and Ida Green Professor of Oceanography, MIT

The CLIMODE FIELD CAMPAIGN Observing the Cycle of Convection and Restratification over the Gulf Stream

The CLIMODE FIELD CAMPAIGN Observing the Cycle of Convection and Restratification over the Gulf Stream.

(Marshall, J. and Andersson, A. and Bates, N. and Dewar, W. and Doney, S. and Edson, J. and Ferrari, R. and Forget, G. and Fratantoni, D. and Gregg, M. and Joyce, T. and Kelly, K. and Lozier, S. and Lumpkin, R. and Maze, G. and Palter, J. and Samelson, R. and Silverthorne, K. and Skyllingstad, E. and Straneo, F. and Talley, L. and Thomas, L. and Toole, J. and Weller, R. and Climode Grp), BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, vol. 90, no. 9, pp. pages, 2009.

Abstract

One of the best-known hydrographic features of the midlatitude oceans is “Sub-Tropical Mode Water” (“STMW”), an upper-ocean water mass characterized by homogeneous properties and extending, in wintertime, to a depth of some 400 m.
Mode waters were first observed over 130 yr ago by Thomson (1877). Since these pioneering observations, they have been found in all midlatitude gyres and adjacent to all major currents, including the Antarctic Circumpolar Current. As suggested by theirname, mode waters are particularly voluminous [see Worthington (1959, 1976) and the review of Hanawa and Talley (2001)]. Given the widespread and pervasive nature of mode waters, it is clear they are a manifestation of very basic ocean dynamics, and yet what those dynamics are has eluded a comprehensive explanation. Moreover, they are of considerable cli matic importance, being formed in a region of intense air–sea exchange where the ocean gives up heat to
the atmosphere (see Fig. 1, top), triggering vigorous wintertime convection on both sides of the air–sea interface.

doi = 10.1175/2009BAMS2706.1