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

摘要

Weekly period meanders and eddies are persistent features of Gulf Stream frontal dynamics from Miami, FL, to Cape Hatteras, NC. 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(degrees) and 32(degrees)N where the Stream approaches the topographic feature known as the Charleston bump and between 34(degrees)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 (open quotes)nutrient pump(close quotes) for the shelf. Annual carbon production on the shelf due to Gulf Stream input is estimated at 7(times)10(sup 12) g C year(sup -1) or about 7 million tons carbon per year. Seasonal carbon cycles are estimated for the outer, mid and inner shelf regions from Gulf Stream nutrient input, carbon production, and carbon export.