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Volume 77, Issue 3, March 2006
Aircraft instrument for simultaneous, in situ measurement of and via pulsed cavity ring-down spectroscopy77(2006); http://dx.doi.org/10.1063/1.2176058View Description Hide Description
This article describes a cavity ring-down spectrometer (CaRDS) specifically designed and constructed for installation on the NOAA WP-3D Orion (P-3) aircraft for sensitive, rapid in situmeasurement of and . While similar to our previously described CaRDS instrument, this instrument has significant improvements in the signal-to-noise ratio, the time resolution, and in overall size and weight. Additionally, the instrument utilizes a custom-built, automated filter changer that was designed and constructed to meet the requirement for removal of particulate matter in the airflow while allowing fully autonomous instrument operation. The CaRDS instrument has a laboratory detection sensitivity of in absorbance or (pptv denotes parts per trillion volume) of in a average, although the typical detection sensitivities encountered in the field were for and for . The instrument accuracy is 25% for and 20%–40% for , limited mainly by the uncertainty in the inlet transmission. The instrument has been deployed on the P-3 aircraft as part of a major field campaign in the summer of 2004 and during several ground and tower deployments near Boulder, CO.