Mediterranean Outflow and Meddies

Project Summary co-PIs: Amy Bower (WHOI), Lawrence Armi (SIO/UCSD), Isabel Ambar (U. Lisbon), and Phil Richardson (WHOI) The Mediterranean salt tongue is a prominent feature of the North Atlantic Ocean at mid-depths. The discovery of isolated lenses of salty Mediterranean Water (meddies) in the last decade has challenged the traditional view of this tongue as a purely advective/diffusive feature. The role of these meddies in the salt and heat budgets of the North Atlantic is not well-understood. We are studying the dispersion of Mediterranean Water into the North Atlantic via meddies and other processes. In 1993-1994, we seeded the Mediterranean Undercurrent near its source with Lagrangian drifters. Forty-nine RAFOS floats were launched sequentially in the Mediterranean Undercurrent south of Portugal and tracked for up to 11 months. Our specific objectives to date have been 1) to identify the most important meddy formation site(s); 2) to make the first direct estimate of the frequency of meddy formation; 3) to document the pathways of meddies and their life histories; and 4) to determine the pathways by which Mediterranean Water which is not trapped in the meddies enters the North Atlantic. The trajectories of floats caught in meddies are easily recognizable due to the persistent and rapid anticyclonic motion associated with these features. As a result of this study, we hope to advance our understanding of how Mediterranean Water enters the subtropical gyre of the North Atlantic.

Manuscripts Bower, A. S., Nuno Serra, and Isabel Ambar, 2002. Structure of the Mediterranean Undercurrent and Mediterranean Water spreading around the southwestern Iberian Peninsula. Journal of Geophysical Research - Oceans, 107(C10), 1-19. Richardson, P. L., A. S. Bower, and W. Zenk, 2000. A census of Meddies tracked by floats. Progress in Oceanography, 45 (2), pp. 209-250. Ambar, I., L. Armi, A. Bower, and T. Ferreira, 1999. Some aspects of time variability of the Mediterranean Water off south Portugal. Deep-Sea Research I, 46, pp. 1109 - 1136. Bower, A. S., L. Armi, and I. Ambar, 1997. Lagrangian observations of Meddy formation during A Medditerranean Undercurrent Seeding Experiment. Journal of Physical Oceanography, 27, pp. 2545 - 2575. Bower, A. S., L. Armi, and I. Ambar, 1995. Direct evidence of meddy formation off the southwest coast of Portugal. Deep-Sea Research I, 42, pp. 1621 - 1630.

Technical Reports Hunt, H. D., C. M. Wooding, C. L. Chandler, and A. S. Bower, 1998. A Mediterranean Undercurrent Seeding Experiment (AMUSE): Part II: RAFOS Float Data Report May 1993 - March 1995. Woods Hole Oceanographic Institution, Technical Memorandum WHOI-98-14, Woods Hole, Massachusetts, 131 pp. Bower, A. S., J. Pallant, and C. L. Chandler, 1997. A Mediterranean Undercurrent Seeding Experiment (AMUSE): Part I: Program Description and Hydrographic Measurements. Woods Hole Oceanographic Institution, Technical Memorandum WHOI-01-97, Woods Hole, Massachusetts, 269 pp.

Data Sets WOCE Float Data Assembly Center (WFDAC)

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