The Concurrent Observation of Methyl Iodide and Dimethyl Sulphide in Marine Air; Implications for Sources of Atmospheric Methyl Iodide

Published In: Atmospheric Environment, v. 33, no. 15, July 1999, p. 2373-2383

Posted on RAND.org on July 01, 1999

by Matt Bassford, Graham Nickles, Peter G. Simmonds, Alastair C. Lewis, Michael J. Pilling, Mathew J. Evans

Read More

Access further information on this document at Elsevier Science Ltd

This article was published outside of RAND. The full text of the article can be found at the link above.

Continuous atmospheric measurements of methyl iodide and dimethyl sulphide were carried out at Mace Head, western Ireland, over a 4-week period in July 1996. The concurrent observations of methyl iodide and dimethyl sulphide reported here display a clear association, indeed statistical analysis indicated a very significant degree of covariance. A simple yet informative use of modelled 5-day back trajectories was employed in tandem with examination of local meteorology to illuminate the geographical source regions of methyl iodide and dimethyl sulphide. The interpretation of the atmospheric observations in terms of air-mass flow has elucidated part of the global methyl iodide cycle and provides evidence for two distinct source regions of methyl iodide: 1. Under certain synoptic meteorological conditions, long-range transport of methyl iodide and dimethyl sulphide was observed from discrete areas of the sub-tropical Atlantic Ocean located in a region between 30-50ºN and 20-50ºW. 2. Measurements taken under different conditions led us to believe that there was an additional source of methyl iodide that influenced the Mace Head atmosphere, most likely produced by coastal macroalgae which inhabit waters off the western coast of Ireland.

Research conducted by

This report is part of the RAND Corporation external publication series. Many RAND studies are published in peer-reviewed scholarly journals, as chapters in commercial books, or as documents published by other organizations.

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.