Carbon Dioxide Active Remote Sensing Using Pulsed 2-µm Lidar

A pulsed 2-mm Integrated Path Differential Absorption (IPDA) lidar was developed at NASA Langley Research Center for high-accuracy and high-precision measurements of atmospheric carbon dioxide (CO₂). The instrument targets the R30 CO₂ absorption line and implements high-energy tunable on-line transmitter and advanced HgCdTe avalanche photodiode receiver. During 2019 airborne validation campaign, the IPDA was tested over the ocean for retrieving the weighted-average column dry-air volume mixing ratio of CO₂ (XCO₂) from 4.5 km altitude. XCO₂ measurement resulted in 404.43 ± 1.23 ppm using 10 s average, as compared to 405.49 ppm from prediction models. This translates to 0.26% and 0.30% relative accuracy and precision, respectively. Performance models were updated to scale the IPDA technology assuming operation from a space platform. Results present XCO₂ measurements using the instrument capabilities considering different target scenarios for Earth’s surface. This demonstrates the potential for the IPDA technique and technology to achieve sustained global CO₂ measurement.