SIT: Sulfur Instrumentation Test

Summary

During October and early November 1999, Alan Bandy from Drexel University installed a new atmospheric pressure ionization mass spectrometer (APIMS) on the NCAR/NSF C130 for determination of sulphur dioxide and dimethyl sulphide (DMS) with a time resolution of at least one measurement per second. This test was an evaluation program flown locally out of Jeffco from 4 to 25 October, and from 5 through 12 November, with one excursion in the marine boundary layer near San Diego. The APIMS was compared to an older gas chromatograph/mass spectrometer, which had a time response of three minutes. During the test flights, the APIMS successfully met the goal of measuring sulphur dioxide in less than one second. Time response and precision of the DMS measurements appear to be similar to that of the sulphur dioxide measurements. Work will continue on the APIMS to develop modifications to avoid chemical interferences for the reaction scheme for DMS.

Russ Davis from the Scripps Institute of Oceanography took advantage of Bandy's project on the NSF/NCAR C-130 to test an aircraft deployable oceanographic buoy. Davis had worked with RAF staff on designing a mechanism for deploying a dummy SOLO float package from the open rear cargo door of the NSF/NCAR C-130 in flight. The instrument was housed in a 6 feet long and 7 inch diameter cardboard "box" weighing about 50 pounds. The package was deployed with a parachute from several thousand feet above the ocean off of San Diego but unfortunately disintegrated upon entering the airstream. Davis and RAF will redesign the package.