Distributions of chlorophyll and primary productivity in relation to water column structure in the eastern North Atlantic Ocean

摘要

Latitudinal variations in the megascale (103km) distribution of biological properties are described in relation to water column structure between 60° and 7°N in the eastern North Atlantic Ocean. Stations were occupied along a meridional transect of stations at 20°W in August‐September, 1988, during the third leg of the National Oceanic and Atmospheric Administration Global Change Expedition. An additional transect to the south (38°N to 7°N) was occupied to extend the total range of latitudinal observations. Chlorophyll a concentrations were highest in the northern latitudes (0.2 mg m−3in the vicintiy of the subtropical gyre, south of 40°N. The nitracline was associated with a shoaling of the pycnocline in the northern latitudes. At 7°N, high chlorophyll concentrations (approximately 0.5 mg m−3), and enhanced primary productivity (375.5 mg C m−2d−1) were associated with a lens of fresh Amazon River Water. Primary productivity rates were variable throughout the transect, ranging from 646.10 mg C m−2d−1to 138.26 mg C m−2d−1. Productivity maxima were located south of Iceland, at 46°N (646.10 mg C m−2d−1) and in the vicinity of the Azores Front at 35°N (259.85 mg C m−2d−1). Latitudinal distributions of primary productivity corresponded closely to a model of productivity along