Gulf Stream frontal eddy influence on productivity of the southeast U.S. continental shelf

Abstract

Weekly period meanders and eddies are persistent features of Gulf Stream frontal dynamics from Miami, Florida, to Cape Hatteras, North Carolina. Satellite imagery and moored current and temperature records reveal a spatial pattern of preferred regions for growth and decay of frontal disturbances. Growth regions occur off Miami, Cape Canaveral, and Cape Fear due to baroclinic instability, and decay occurs in the confines of the Straits of Florida between Miami and Palm Beach, between 30° and 32°N where the stream approaches the topographic feature known as the Charleston bump and between 33°N and Cape Hatteras. Eddy decay regions are associated with elongation of frontal features, offshore transport of momentum and heat, and onshore transport of nutrients. Onshore transport of new nitrogen from the nutrient‐bearing strata beneath the Gulf Stream indicates that frontal eddies serve as a “nutrient pump” for the shelf. New nitrogen flux to the shelf due to Gulf Stream input could support new production of 7.4×1012 g C yr−1 or about 8 million tons carbon per year if all nitrate were utilized. Calculations indicate that approximately 70% of this potential new production is realized, yielding an annual new production for the outer shelf of 4.3×1012 g C.

The effect of the Leeuwin Current on phytoplankton biomass and production off Southwestern Australia

“…[43] A similar mechanism has been described for several western boundary currents, where eddies and meanders over the continental slope ''pump'' nutrients onto the continental shelf and thereby promote a significant proportion of the shelf productivity off the southeast USA [Yoder et al, 1981;Lee and Atkinson, 1983;Lee et al, 1989Lee et al, , 1991, Brazil [Campos et al, 2000], Japan [Kimura et al, 1997], and eastern Australia [Tranter et al, 1986;Harris et al, 1987]. The western boundary currents are often notably low in nutrients, yet the eddy and meander structures promote shelf productivity through eddy-induced upwelling along the shelf break, because the nitricline is lifted upward toward the continental shelf.…”

“…Meanders and eddies spin up during the autumnwinter period and often continue to evolve through winter, to be either reabsorbed or shed into the interior of the eastern Indian Ocean and drift westward Fang and Morrow, 2003]. Western boundary current eddies and meanders have been shown to contribute significantly to the productivity of the continental shelves off the southeastern USA [Yoder et al, 1981;Lee and Atkinson, 1983;Lee et al, 1989Lee et al, , 1991, Brazil [Campos et al, 2000], Japan [Kimura et al, 1997], and eastern Australia [Tranter et al, 1986;Harris et al, 1987], but the impact of eddies off the coast of Western Australia on shelf productivity has not been previously examined.…”

Physical forcing of phytoplankton community structure and primary production in continental shelf waters of the Western Antarctic Peninsula

“…Estimates of the nutrient and carbon fluxes associated with intrusion events on these continental shelves (e.g. Lee et al, 1991) show that these events account for a significant portion of organic matter production. On the southeastern U.S. continental shelf, phytoplankton production and biomass are Ͼ10 times higher within intrusions than surrounding resident shelf waters (Yoder, 1985).…”

Wind and Gulf Stream influences on along‐shelf transport and off‐shelf export at Cape Hatteras, North Carolina

“…Here Mid-Atlantic Bight (MAB) and South Atlantic Bight (SAB) shelf waters meet, and a large freshwater influx enters the coastal ocean from the landward edge [Manning, 1991]. Gulf Stream meanders progress past the cape [Glenn and Ebbesmeyer, 1994a], possibly decaying and importing slope water into the coastal regime [Lee et al, 1991 ]. Gulf Stream filaments overwash the narrow shelf and participate in var- One integrated way to address the net effect of these processes is through the assessment of volume transport.…”