G2401-mc Picarro Instrument for Airborne Measurement of Carbon Dioxide (CO2), Methane (CH4), Carbon Monoxide (CO), and Water Vapor (H2O) Instrument
The Picarro G2401-mc utillzes wavelength scanned cavity ring down spectroscopy, a technique wherein the exponential decay of optical extinction within a resonant cavity is modified by molecular absorption. This decay time is called a ring-down time. Over a specific wavelength range, ring-down times are proportional to the concentration of the absorbing species. The figure below shows a schematic of the instrument design on the left and typical time series traces on the right.
Measurements Provided: Dry mole fraction of carbon dioxide, methane and carbon monoxide and water vapor mole fraction
Typical Sampling Rates: 0.25 - 0.77 Hz
History of Significant Changes: In 2018 EOL purchased software changes from Picarro to create a low cell pressure mode and thus allow high altitude operation without the addition of an inlet compressor. ACOM collaborators created a third mode option and made other refinements to the configuration code in order to allow several user options. These modifications were flight implemented and tested in order to support the 2019-2021 MethaneAIR project.
Hourly in-flight calibrations of 2-4 minute duration are typically conducted with 1 or 2 working standards, typically in coordination with other sensors. Working standard concentrations are traceable to WMO network by laboratory calibration against NOAA GMD primary standard suite maintained by RAF.