Nitrous oxide in the surface layer of the tropical North Atlantic Ocean along a west to east transect

Abstract

Nitrous oxide (N2O) was measured during the first German SOLAS (Surface Ocean - Lower Atmosphere Study) cruise in the tropical North Atlantic Ocean on board R/V Meteor during October/November 2002. About 900 atmospheric and dissolved N2O measurements were performed with a semi-continuous GC-ECD system equipped with a seawater-gas equilibrator. Surface waters along the main transect at 10°N showed no distinct longitudinal gradient. Instead, N2O saturations were highly variable ranging from 97% to 118% (in the Guinea Dome Area, 11°N, 24°W). When approaching the continental shelf of West Africa, N2O surface saturations went up to 113%. N2O saturations in the region of the equatorial upwelling (at 0-1.5°N, 23.5-26°W) were correlated with decreasing sea surface temperatures and showed saturations up to 109%. The overall mean N2O saturation was 104 ± 4% indicating that the tropical North Atlantic Ocean is a net source of atmospheric N2O. Copyright 2004 by the American Geophysical Union.