Atmospheric Carbon Dioxide Measurement Using 1.5-µm Double- Pulse IPDA lidar over the Desert

Abstract

Abstract The Integrated Path Differential Absorption (IPDA) lidar is capable of accurately measuring regional carbon dioxide (CO2) column concentrations, which is crucial for understanding the carbon cycle in the biosphere and predicting future climate change. The space-borne IPDA lidar has become the preferred sensor for measuring global CO2 column concentrations(XCO2) on days and nights. To validate the data processing methods of space-borne lidar, an airborne IPDA lidar was designed for a flight experiment.In July 2021, the airborne experiment was implemented in Dunhuang, Gansu Province, China (39–41°N, 93–96°E), where the aircraft was equipped with a developed lidar that could measure both aerosols profiles and CO2 concentrations, a wind measurement lidar, and an in-situ greenhouse gas analyzer (GGA). To minimize measurement errors, the energy monitoring part was optimized. The differential absorption optical depth (DAOD) was calculated using the Pulse Integral Method (PIM) algorithm, and the CO2 column-averaged dry-air mixing ratio was calculated using various averaging methods. The IPDA lidar measured XCO2 over the Dunhuang validation site to be 405.572 ppm, with a long-term correlation coefficien of 91.2% with the GGA. Furthermore, the IPDA lidar and the LGR both measured changes in XCO2 concentration resulting from aircraft exhaust.