Atmospheric boundary layer CO2 remote sensing with a direct detection LIDAR instrument based on a widely tunable optical parametric source
Résumé
We report on the capability of a direct detection differential absorption lidar (DIAL) for range resolved and integrated path (IPDIAL) remote sensing of CO2 in the atmospheric boundary layer (ABL). The laser source is an amplified nested cavity optical parametric oscillator (NesCOPO) emitting approximately 8 mJ at the two measurement wavelengths selected near 2050 nm. Direct detection atmospheric measurements are taken from the ground using a 30 Hz frequency switching between emitted wavelengths. Results show that comparable precision measurements are achieved in DIAL and IPDIAL modes (not better than a few ppm) on high SNR targets such as near range ABL aerosol and clouds, respectively. Instrumental limitations are analyzed and degradation due to cloud scattering variability is discussed to explain observed DIAL and IPDIAL limitations.
Une mesure lidar à absorption différentielle (DIAL) du CO2 atmosphérique est réalisée en détection directe. La source émetteur du Lidar est une source paramétrique de type NesCOPO, émettant plusieurs mJ à 2050 nm. Les modes de mesure DIAL (concentration du CO2 résolue spatialement, par rétrodiffusion sur les aerosols) et IP-DIAL (intégrée, en utilisant les échos nuageux) sont testés et leurs limitations instrumentales expliquées.