New production in the warm waters of the Tropical Pacific Ocean

Abstract

The average depth-integrated rate of new production in the tropical Pacific Ocean was estimated from a calculation of horizontal and vertical nitrate balance over the region enclosed by the climatological 26 degree C isotherm. The net turbulent flux of nitrate into the region was computed in terms of the climatological net surface heat flux and the nitrate-temperature relationship at the base of the 26 degree C isotherm. The net advective transport of nitrate into the region was estimated using the mean nitrate distribution obtained from the analysis of historical data and previous results of a general circulation model of the tropical Pacific. The rate of new production resulting from vertical turbulent fluxes of nitrate was found to be similar in magnitude to that due to advective transport. Most (about 75%) of the advective input of nitrate was due to the horizontal transport of nutrient-rich water from the eastern equatorial region rather than from equatorial upwelling.