Ultrasonic Detector for High Precision Measurements of Carbon Dioxide

摘要

A new instrument for monitoring atmospheric CO2 hasnbeen developed based on the measurement of thenspeed of sound in air. The instrument uses a selectivenscrubber to yield highly precise and accurate measurementsnof CO2 mixing ratios at ambient concentrations.nThe instrument has a precision of 0.3 ppmv (1σ) withna signal that is independent of pressure and requiresna flow rate of only 30 mL/min. Laboratory measurementsnof atmospheric CO2 showed excellent agreementnwith values obtained by nondispersive infrared absorption.nThe instrument has the advantage of collectingncontinuous, high-precision data every 25 s and can benmodified for vertical profiling studies using kites,nballoons, or light aircraft for the purpose of measuringnlandscape-scale fluxes.