An improved fast‐response vacuum‐UV resonance fluorescence CO instrument

Abstract

The fast‐response resonance fluorescence instrument for the airborne measurement of carbon monoxide described by Gerbig et al. [1996] was modified by implementing an improved optical filter with more efficient optics and an optimized resonance lamp. Besides reductions in size and weight, the new instrument achieves a sensitivity 10 times higher, a lower background (65 ppb compared with 250 ppb), and a faster time response (<0.1 s) than the original instrument. The precision is ±1.5 ppb at an atmospheric mixing ratio of 100 ppb CO, and the detection limit is 3 ppb (2σ) for an integration time of 1 s. First results from the North Atlantic Regional Aerosol Characterization Experiment (ACE‐2) campaign during July 1997, when the new instrument was deployed aboard the U.K. Meteorological Office C‐130 aircraft, are used to demonstrate the performance of the new instrument.