Gostlow, Brian and Robinson, Andrew and Harris, Niel and O'Brien, L and Oram, David and Mills, Graham and Newton, Hannah and Yong, S and Pyle, John (2010) μDirac: an autonomous instrument for halocarbon measurements. Atmospheric Measurement Techniques, 3 (2). pp. 507-521. ISSN 1867-1381
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Abstract
We describe a new instrument (μDirac) capable of measuring halocarbons in the atmosphere. Portability, power efficiency and autonomy were critical design requirements and the resulting instrument can be readily deployed unattended on a range of platforms: long duration balloon, aircraft, ship and ground-based stations. The instrument is a temperature programmed gas chromatograph with electron capture detector (GC-ECD). The design requirements led to μDirac being built in-house with several novel features. It currently measures a range of halocarbons (including short-lived tracers having biogenic and anthropogenic sources) with measurement precision relative standard deviations ranging from±1% (CCl4) to±9% (CH3I). The prototype instrument was first tested in 2005 and the instrument has been proved in the field on technically challenging aircraft and ground-based campaigns. Results from an aircraft and a ground-based deployment are described.