Laser diode absorption spectroscopy for accurate CO2 line parameters at 2 μm: consequences for space-based DIAL measurements and potential biases
Résumé
Space-based active sensing of CO2 concentration is a very promising technique for the derivation of CO2 surface fluxes. There is a need for accurate spectroscopic parameters to enable accurate space-based measurements to address global climatic issues. New spectroscopic measurements using laser diode absorption spectroscopy are presented for the preselected R30 CO2 absorption line ((2001)III←(000) band) and four others. The line strength, air-broadening halfwidth, and its temperature dependence have been investigated. The results exhibit significant improvement for the R30 CO2 absorption line: 0.4% on the line strength, 0.15% on the air-broadening coefficient, and 0.45% on its temperature dependence. Analysis of potential biases of space-based DIAL CO2 mixing ratio measurements associated to spectroscopic parameter uncertainties are presented.