Pulsed airborne lidar measurements of CO_2 column absorption

摘要

We report on airborne lidar measurements of atmospheric CO_2 column density for an approach being developed as a candidate for NASA's ASCENDS mission. It uses a pulsed dual-wavelength lidar measurement based on the integrated path differential absorption (IPDA) technique. We demonstrated the approach using the CO_2 measurement from aircraft in July and August 2009 over four locations. The results show clear CO_2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The 2009 measurements have been analyzed in detail and the results show ～1 ppm random errors for 8-10 km altitudes and ～30 sec averaging times. Airborne measurements were also made in 2010 with stronger signals and initial analysis shows ～ 0.3 ppm random errors for 80 sec averaging times for measurements at altitudes >6 km.