Autonomous Airborne Mid-IR Spectrometer for High Precision Measurements of Ethane during the NASA ACT-America Studies Journal Article uri icon



  • Abstract. An airborne trace gas sensor based on mid-infrared technology is presented for fast (1-second) and high precision ethane measurements during the Atmospheric Carbon and Transport-America (ACT-America) study. The ACT-America campaign is a multi-year effort to better understand and quantify sources and sinks for the two major greenhouse gases carbon dioxide and methane. Simultaneous airborne ethane and methane measurements provide one method by which sources of methane can be identified and quantified. The instrument described herein was operated on NASA's B200 King Air airplane spanning five separate field deployments. As this platform has limited payload capabilities, considerable effort was devoted to minimizing instrument weight and size without sacrificing airborne ethane measurement performance. This paper describes the numerous features designed to achieve these goals. Two of the key instrument features that were realized were autonomous instrument control with no on-board operator and the implementation of direct absorption spectroscopy based on fundamental first principles. We present airborne measurement performance for ethane based upon the precisions of zero air background measurements as well as ambient precision during quiescent stable periods. The airborne performance was improved with each successive deployment phase, and we summarize the major upgraded design features to achieve these improvements. During the 4th deployment phase, in the spring of 2018, the instrument achieved 1-second (1σ) airborne ethane precisions reproducibly in the 30–40 parts-per-trillion by volume (pptv) range in both the boundary layer and the less turbulent free troposphere. This performance is among some of the best reported to date for fast (1 Hz) airborne ethane measurements. In both the laboratory conditions and at times during calm and level airborne operation these precisions were as low as 15–20 pptv.;

publication date

  • June 26, 2020

has restriction

  • green

Date in CU Experts

  • January 6, 2021 1:17 AM

Full Author List

  • Weibring P; Richter D; Walega JG; Fried A; DiGangi J; Halliday H; Choi Y; Baier B; Sweeney C; Miller B

author count

  • 13

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