Articles | Volume 10, issue 12
Research article
12 Dec 2017
Research article |  | 12 Dec 2017

A new non-resonant laser-induced fluorescence instrument for the airborne in situ measurement of formaldehyde

Jason M. St. Clair, Andrew K. Swanson, Steven A. Bailey, Glenn M. Wolfe, Josette E. Marrero, Laura T. Iraci, John G. Hagopian, and Thomas F. Hanisco

Abstract. A new in situ instrument for gas-phase formaldehyde (HCHO), COmpact Formaldehyde FluorescencE Experiment (COFFEE), is presented. COFFEE utilizes non-resonant laser-induced fluorescence (NR-LIF) to measure HCHO, with 300 mW of 40 kHz 355 nm laser output exciting multiple HCHO absorption features. The resulting HCHO fluorescence is collected at 5 ns resolution, and the fluorescence time profile is fit to yield the ambient HCHO mixing ratio. Typical 1σ precision at  ∼  0 pptv HCHO is 150 pptv for 1 s data. The compact instrument was designed to operate with minimal in-flight operator interaction and infrequent maintenance (1–2 times per year). COFFEE fits in the wing pod of the Alpha Jet stationed at the NASA Ames Research Center and has successfully collected HCHO data on 27 flights through 2017 March. The frequent flights, combined with a potentially long-term data set, makes the Alpha Jet a promising platform for validation of satellite-based column HCHO.

Short summary
Formaldehyde is an abundant, photochemically influential trace species in the Earth’s atmosphere. We present a new instrument for measuring atmospheric formaldehyde using a laser-based measurement technique that is more compact and lower cost than previous laser-based formaldehyde instruments. The instrument is part of the Alpha Jet Atmospheric eXperiment (AJAX) payload at the NASA Ames Research Center and has collected data on 27 flights between December 2015 and March 2017.