Abstract
This paper reports results from NASA's Chemical Instrumentation and Test Evaluation (CITE 3) during which airborne measurements of dimethyl sulfide (DMS) from six instruments were intercompared. Represented by the six instruments are three fundamentally different detection principles (flame photometric, mass spectrometric, and electron capture after fluorination); three collection/preconcentration methods (cryogenic, gold wool absorption, and polymer absorbent); and three types of oxidant scrubbers (solid phase alkaline, aqueous reactor, and cotton). The measurements were made over the Atlantic Ocean in August/September 1989 during flights from NASA's Wallops Flight Center, Virginia, and Natal, Brazil. The majority of the intercomparisons are at DMS mixing ratios <50 pptv. Results show that instrument agreement is of the order of a few pptv for mixing ratios <50 pptv and to within about 15% above 50 pptv. Statistically significant (95% confidence) measurement biases were noted among some of the techniques. However, in all cases, any bias is small and within the accuracy of the measurements and prepared DMS standards. Thus, we conclude that the techniques intercompared during CITE 3 provide equally valid measurements of DMS in the range of a few pptv to 100 pptv (upper range of the intercomparisons).
Highlights
Sulfur gases and their reaction products play important roles in the chemistry of the global troposphere and in the biogeochemical sulfur cycle [e.g., Cullis and Hirschler, 1980; Rodhe and Isaksen, 1980; Freney et al, 1983; Ivanov and Freney, 1983; Galloway et al, 1985; Toon et al, 1987; Saltzman and Cooper, 1988; Bates et al, 1987, 1990; Andreae, 1990; Andreae and Jaeschke, 1992]
This paper reports the results from Chemical Instrumentation Test andEvaluation (CITE) 3 during which airborne measurements from six dimethyl sulfide (DMS) instruments were intercompared
DMS standardsintercomparisonsshowed that within the stated uncertainties, all the measurements agreed with the National Institute of Standards and Technology (NIST) standards
Summary
Sulfur gases and their reaction products play important roles in the chemistry of the global troposphere and in the biogeochemical sulfur cycle [e.g., Cullis and Hirschler, 1980; Rodhe and Isaksen, 1980; Freney et al, 1983; Ivanov and Freney, 1983; Galloway et al, 1985; Toon et al, 1987; Saltzman and Cooper, 1988; Bates et al, 1987, 1990; Andreae, 1990; Andreae and Jaeschke, 1992]. MSA and sulfuric acid are incorporated into the atmospheric aerosol and represent the dominant source of aerosol particles in the unpolluted marine atmosphere [NASA, 1984; Andreae, 1990]. Important scientific issues in atmospheric sulfur chemistry include (1) the relative role of the various. Rosenstiel School of Marine and Atmospheric, Miami, Florida. 0148-0227/93/93 JD-00688505.00 sources and sinks (natural and anthropogenic) of the major sulfur gases, (2) the rates and pathways of atmospheric oxidationof thesulfurspeciesto SO2andtheproductionof aerosols, (3) the vertical distribution of sulfur gases and aerosols and their transport between the mixed layer and free troposphere, (4) the role of sulfur in acid rain, and (5) the impact of sulfate aerosol production (stratosphere and troposphere) as it relates to the Earth' s energy balance and climate [Charlson et al, 1987] Paper number 93JD00688. 0148-0227/93/93 JD-00688505.00 sources and sinks (natural and anthropogenic) of the major sulfur gases, (2) the rates and pathways of atmospheric oxidationof thesulfurspeciesto SO2andtheproductionof aerosols, (3) the vertical distribution of sulfur gases and aerosols and their transport between the mixed layer and free troposphere, (4) the role of sulfur in acid rain, and (5) the impact of sulfate aerosol production (stratosphere and troposphere) as it relates to the Earth' s energy balance and climate [Charlson et al, 1987]
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