Preprints
https://doi.org/10.5194/amt-2021-28
https://doi.org/10.5194/amt-2021-28

  19 Feb 2021

19 Feb 2021

Review status: this preprint is currently under review for the journal AMT.

Airborne Mid-Infrared Cavity enhanced Absorption spectrometer (AMICA)

Corinna Kloss1,a, Vicheith Tan1, J. Brian Leen2, Garrett L. Madsen2, Aaron Gardner2, Xu Du2, Thomas Kulessa3, Johannes Schillings3, Herbert Schneider3, Stefanie Schrade1, Chenxi Qiu1, and Marc von Hobe1 Corinna Kloss et al.
  • 1Institute for Energy and Climate Research (IEK-7), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
  • 2ABB Los Gatos, San Jose, U.S.A.
  • 3Central Institute for Engineering, Electronics and Analytics (ZEA), Engineering and Technology (ZEA-1), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
  • anow at: Laboratoire de Physique et Chimie de l’Environnement et de l’Espace (LPC2E), Université d’Orléans, CNRS, Orléans, France

Abstract. We describe the Airborne Mid-Infrared Cavity enhanced Absorption spectrometer (AMICA) designed to measure trace gases in situ on research aircraft using Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS). AMICA contains two largely independent and exchangeable OA-ICOS arrangements, allowing for the simultaneous measurement of multiple substances in different infrared wavelength windows tailored to scientific questions related to a particular flight mission. Three OA-ICOS setups have been implemented to measure OCS, CO2, CO and H2O at 2050 cm−1, O3, NH3 and CO2 at 1035 cm−1, and HCN, C2H2 and N2O at 3331 cm−1. The 2050 cm−1 setup has been fully characterized in the lab and successfully used for atmospheric measurements during two campaigns with the research aircraft M55-Geophysica and one with the German HALO aircraft. Nominal measurement precision is 30 ppt for OCS, 1 ppm for CO2, 3 ppb for CO and 100 ppm for H2O. The 1035 and 3331 cm−1 arrangements have only partially been characterized and are still in development. The ~100 kg instrument with a typical in-flight power consumption of about 500 VA is dimensioned to fit into one 19 inch rack typically used for deployment inside the aircraft cabin. Its rugged design and a pressurized and temperature stabilized compartment containing the sensitive optical and electronic hardware also allow for deployment in payload bays outside the pressurized cabin even at high altitudes of 20 km. A sample flow system with two parallel proportional solenoid valves of different size orifices allows for precise regulation of cavity pressure over the wide range of inlet port pressures encountered between the ground and maximum flight altitudes. Sample flow on the order of 1 SLM maintained by an exhaust-side pump limits the useful time resolution to about 2.5 s (corresponding to the average cavity flush time).

Corinna Kloss et al.

Status: open (until 16 Apr 2021)

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Corinna Kloss et al.

Corinna Kloss et al.

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Short summary
We describe the innovative analyzer AMICA for airborne trace gas measurements by infrared spectroscopy. Its design makes it robust and allows for sensitive measurements. AMICA has been used on two different aircraft for measuring gases including carbonyl sulfide, carbon monoxide and ozone. With fairly simple adaptions, AMICA can measure many stable trace gases that absorb light in the infrared.