Support of MethaneAIR-2 with improved 4-channel CRDS greenhouse gas instrument

The ACOM/EOL Core Tracer airborne greenhouse gas Cavity Ring Down Spectrometer (CRDS) was modified to improve the time resolution when measuring at altitudes above 8 km. Performance under flight conditions was confirmed during deployment in support of the Summer 2021 MethaneAIR campaign. MethaneAIR was an NSF-funded series of test flights designed to demonstrate the capability of the MethaneAIR imaging spectrometer, an airborne simulator and precursor of MethaneSAT and developed as part of the Environmental Defense Fund International Methane Project.

The CRDS modifications consisted of degrading the spectroscopic characterization of the carbon monoxide channel and thereby increasing the overall 4-channel measurement time resolution to 2 seconds. This factor of two improvement in time response did not affect the precision of carbon dioxide and methane observations, each channel maintaining precisions of 0.07 ppmv and 0.5 ppbv, respectively.