Cavity ringdown analyzer for atmospheric inversion and eddy-covariance flux measurements

Methane (CH ₄), water vapor (H ₂O), and carbon dioxide (CO ₂) are collectively responsible for the majority of the Earth's greenhouse effect. Robust instrumentation that could measure these gases with both high accuracy and high precision would reduce the uncertainty in determination of terrestrial sources and sinks of these dominant greenhouse gases, resulting in improved predictive models and a better understanding of the human contribution to global warming. This article describes a field-deployable cavity ring-down spectrometer capable of performing, in a single instrument, atmospheric inversion and high-speed eddy-covariance flux measurements of these important greenhouse gases. Because this instrument does not require frequent calibration and maintains high linearity, precision, and accuracy over changing environmental conditions, the instrument enables reduced operating costs and high-density field deployment.