Airborne measurements of the partial column-averaged dry-air mixing ratio of CO
2 (XCO
2) 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 XCO
2 observed from LAS and XCO
2 calculated from
in situ measurements. The average XCO
2 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.
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