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The Air-Sea Interface
R/V Asterias accompanies the SCIMS semi-autonomous microlayer sampling catamaran along a southeasterly transect near the Air-Sea Interaction Tower (ASIT) of the Martha's Vineyard Coastal Observatory during the ONR CBLAST main experiment (August 2003). Numerous banded surface film features (light areas) evident in the field of view are also recorded in the CDOM fluorescence record. Photo courtesy of M. McElroy, WHOI (click for enlarged version).
Chemical Mapping of the Sea-Surface Microlayer: A System for Measurement of Spatial and Temporal Variations in Composition

  The viscoelastic behavior of the air-sea interface, a key parameter affecting air-sea exchange of mass, momentum and heat, is strongly dependent on naturally-occurring adsorbed surfactant materials. The long-term goals of this work are to understand the relationship between the composition of surface-active organic matter in the marine microlayer and the viscoelasticity of the sea surface and to delineate the role of microlayer films in modulating roughness and near-surface turbulence.

  The occurrence, spatial distribution, concentration and composition of sea surface films are not well known. In order to develop such information, this project focuses on designing and deploying systems to detect and measure organic analytes in the marine microlayer in near-real time. Responding to a broad range of organic compounds, such systems can provide specific information on the composition and structure of surface-active materials and estimates of surface enrichments of specific surfactants that control the viscoelasticity of the sea surface. A new survey tool, SCIMS (Slick Chemical Identification and Measurement System), which detects the presence of surface microlayer films and allows mapping their spatial and temporal distributions, is being deployed for seasonally distributed observations at the Martha's Vineyard Coastal Observatory (MVCO) off Cape Cod. SCIMS consists of a surface microlayer skimmer that is coupled to a fluorometry package and an automated extraction interface. It is used in conjunction with innovative ion trap mass spectrometry technology to study microlayer film accumulations and their specific composition. SCIMS is also being deployed in support of the ONR-sponsored Coupled Boundary Layers/Air-Sea Transfer (CBLAST) Defense Research Initiative - Low Wind Component.

Funding Acknowledgment
The development of SCIMS has been jointly sponsored by the National Science Foundation Chemical Oceanography Program (OCE-9811279) and by the Office of Naval Research, Chemical Oceanography Programs (N000149810593).

Reference
Nelson, R. K, Frew, N. M., N. Witzell, F. T. Thwaites and C. G. Johnson, SCIMS - A semi-autonomous system for sampling and extraction of surfactants in the sea-surface microlayer, EOS Trans. AGU, 83(4), Ocean Sciences Meet. Suppl., Abstract OS12A-120, 2002 (Poster - pdf version).