An 1.57 μm Optical Fiber-based Differential Laser Absorption Spectrometer for a Column-averaged Dry Air Mixing Ratio of Atmospheric Carbon Dioxide

Abstract

Airborne measurements of the partial column-averaged dry-air mixing ratio of CO₂ (XCO₂) and moderate airplane height detection were performed using an amplitude-modulated 1.57-μm differential laser absorption spectrometer (LAS). The LAS system proved to be compact, reliable, and rigid in the field measurements. Airborne demonstration flights resulted in a high correlation coefficient of 0.987 between XCO₂ observed from LAS and XCO₂ calculated from in situ measurements. The average XCO₂ obtained from LAS and in situ data agreed within 1.5 ppm, and the method achieved a measurement precision of 2.5 ppm for spiral measurements.