Lidar Approach for Global Atmospheric Column CO2 Measurements

Advanced knowledge in atmospheric CO2 distributions is critical in predicting the Earth's future climate. Large uncertainties in the prediction persist due to limited observations. This study focuses on the development and demonstration of the Intensity-Modulated Continuous-Wave (IM-CW) lidar for atmospheric CO2 measurements. Simulations show that IM-CW lidar systems operating at 1.57 um will provide precise atmospheric column CO2 measurements from space. Airborne systems have demonstrated the feasibility of the technology and instrumentation for space active atmospheric CO2 missions. In this presentation, the atmospheric CO2 column measurements from airborne flight campaigns and lidar system simulations for space missions will be discussed. Data analysis shows that airborne lidar CO2 column measurements over desert and vegetated surfaces agree well with in-situ measurements. A measurement precision of 0.08% or ~0.3 ppmv for a 10-s average over these surfaces has also been achieved. Generally, airborne flight campaigns have demonstrated that the column CO2 measurements of the current IM-CW lidar systems meet the accuracy and precision requirements of atmospheric CO2 measurements. Furthermore, analyses of space CO2 measurements shows that the current IM-CW lidar technology and approach will enable space missions to achieve their science goals.