| Popis: |
Previous work has shown that during early summer, the partial pressure of CO2 (pCO(2)) in surface waters north of about 45 degreesN in the Atlantic exhibits widespread undersaturation. In many areas. this follows after a "spring bloom" of phytoplankton, at which time, nutrient concentrations and pCO(2) decrease sharply from their winter surface values. As part of OMEX I, the late summer distribution of surface water pCO(2) was surveyed in the northeastern Atlantic on cruises of R/V Poseidon and R/V Belgica in 1995. The pattern of the surface distribution of the sea-air pCO(2) difference (Delta pCO(2)) measured on these ship surveys was generally iri accord with that observed in this area in early to mid-summer of 1981. The greatest CO2 undersaturation (-95 mu atm) during our surveys was observed near the west coast of Iceland, with Delta pCO(2) increasing to about -60 mu atm away from the coast. In shelf waters south of Ireland, the pCO(2) was relatively higher than in surface waters of the open ocean adjacent to the Celtic Shelf margin, but the Celtic Shelf waters were still undersaturated relative to the atmospheric CO2 concentration. Because of the variation of wind speed, the synoptic distribution of air-sea CO2 flux, derived from the transfer velocity and Delta pCO(2), does not resemble the distribution of Delta pCO(2) itself. The sharp increase in wind speed at about 53 degreesN, 20 degreesW during the R/V Poseidon survey produces an order of magnitude rise in the estimated air-sea flux of CO2, to a level of about 10-14 mol m(-2) a(-1). The overall synoptic picture appears to be one of moving centers of higher air-sea fluxes that occur where storms pass over regions of surface water pCO(2) undersaturation. |
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