Publications [#184983] of William L Chameides

Papers Published

  1. Shon, ZH and Davis, D and Chen, G and Grodzinsky, G and Bandy, A and Thornton, D and Sandholm, S and Bradshaw, J and Stickel, R and Chameides, W and Kok, G and Russell, L and Mauldin, L and Tanner, D and Eisele, F, Evaluation of the DMS flux and its conversion to SO2 over the southern ocean, ATMOSPHERIC ENVIRONMENT, vol. 35 no. 1 (2001), pp. 159-172, ISSN 1352-2310
    (last updated on 2010/12/22)

    Abstract:
    A total of 16 boundary layer (BL) DMS flux values were derived from fights over the Southern Ocean. DMS flux values were derived from airborne observations recorded during the Aerosol Characterization Experiment (ACE I). The latitude range covered was 55 degreesS-40 degreesS. The method of evaluation was based on the mass-balance photochemical-modeling (MBPCM) approach. The estimated flux for the above latitude range was 0.4-7.0 mu mol m(-2) d(-1). The average value from all data analyzed was 2.6 +/- 1.8 mu mol m(-2) d(-1). A comparison of the MBPCM methodology with several other DMS flux methods (e.g., ship and airborne based) revealed reasonably good agreement in some cases and significant disagreement in other cases. Considering the limited number of cases compared and the fact that conditions for the comparisons were far from ideal, it is not possible to conclude that major agreement or differences have been established between these methods. A major result from this study was the finding that DMS oxidation is a major source of BL SO2 over the Southern Ocean. Model simulations suggest that, on average, the conversion efficiency is 0.7 or higher, given a lifetime for SO2 of similar to 1d. A comparison of two sulfur case studies, one based on DMS-SO2 data generated on the NCAR C-130 aircraft, the other based on data recorded on the NOAA ship Discoverer, revealed qualitative agreement in finding that DMS was a major source of Southern Ocean SO2. On the other hand, significant disagreement was found regarding the DMS/SO2 conversion efficiency (e.g., 0.3-0.5 versus 0.7-0.9). Although yet unknown factors, such as vertical mixing, may be involved in reducing the level of disagreement, it does appear at this time that some significant portion of this difference may be related to systematic differences in the two different techniques employed to measure SO2. It would seem prudent, therefore, that further instrument intercomparison SO2 studies be considered. It also would be desirable to stage new intercomparison activity between the MBPCM flux approach and the air-to-sea gradient as well as other flux methods, but under far more favorable conditions. (C) 2000 Elsevier Science Ltd. All rights reserved.

x