PERSPECTIVE / PERSPECTIVE Direct measurements of biogenic

dimethylsulphide fluxes from the oceans: a synthesis1 H.J. Zemmelink, J.W.H. Dacey, and E.J. Hintsa Abstract: This paper provides a brief overview of the state-of-the-art of techniques that are currently used for field measurements of trace gas fluxes and the subsequent derivation of gas transfer rates over the oceans. Special attention is given to the relaxed eddy accumulation (REA) and gradient flux (GF) techniques, which rely on empirical functions thus far mainly validated over land. The universality of these functions and their application at sea have not yet been fully evaluated. New experiments have shown that the emission of dimethylsulphide (DMS) can be measured by the REA and GF techniques. Moreover, these measurements have provided parameterizations of gas exchange rates that are within the range of relationships between wind speed and gas transfer that have recently been derived from eddy corre-lation (EC) and deliberate tracer measurements. Using DMS as a model, gas is potentially a powerful approach to intercalibrate the REA, GF, and EC techniques, test their applicability in the marine environment, and investigate pro-cesses that determine trace gas exchange across the ocean surface. Résumé: Nous présentons ici une courte synthèse des meilleures techniques courantes utilisées pour mesurer en nature les flux de gaz en traces et pour ensuite dériver les taux de transferts des gaz au-dessus des océans. Il est particulière