9625141 Farwell This award is to develop a validated, mobile system for the preparation and delivery of test gas mixtures. In addition to testing analytical performance features such as detectability, dynamic range, precision, and selectivity, the improved system will enable the assessment of method response times by varying the test gas concentrations with time in a rapid, controlled manner in order to more realistically mimic atmospheric conditions. Reliable measurements of tropospheric sulfur gases such as sulfur dioxide, dimethyl sulfide, and others are important for our understanding of the albedo effect of sulfate aerosol produced from marine biogenic emissions, acidic precipitation, and the biogeochemical sulfur cycle. In the absence of absolutely known standards, which do not exist for sulfur dioxide and other sulfur gases, intercomparison experiments involving several different measurement methods present the best forum for assessing the quantitative reliability of these methods.
