Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption during the ASCENDS 2009 & 2010 Airborne Campaigns

James B Abshire, NASA-Goddard, james.b.abshire@nasa.gov
Haris Riris, NASA-Goddard, haris.riris@nasa.gov (Presenter)
Clark J. Weaver, UMBC-GEST, clarkjweaver@gmail.com
Graham R. Allan, Sigma Space, graham.r.allan@nasa.gov
Xiaoli Sun, NASA-Goddard, xiaoli.sun@nasa.gov
William E. Hasselbrack, Sigma Space, william.e.hasselbrack@nasa.gov
Edward V. Browell, NASA-Langley, edward.v.browell@nasa.gov

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA’s ASCENDS mission and have demonstrated the CO2 measurements from aircraft. For the 2009 ASCENDS campaign we flew the CO2 lidar on a Lear-25 aircraft, and measured the absorption line shapes of the CO2 line using 20 wavelength samples per scan. Measurements were made at stepped altitudes from 3 to 12.6 km over the Lamont OK, central Illinois, North Carolina, and over the Virginia Eastern Shore. Clear CO2 line shapes were observed at all altitudes. Most flights had 5-6 altitude steps with ~250 seconds of recorded measurements per step. We solved for the best-fit CO2 absorption line shape, and calculated the DOD of the fitted CO2 line, and computed its statistics at the altitude steps. We compared them to CO2 optical depths calculated from spectroscopy based on HITRAN 2008 and the column number densities calculated from the airborne in-situ readings.

The 2009 measurements have been analyzed and they were similar on all flights. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. They showed the expected nearly the linear dependence of DOD vs altitude. The measurements showed ~1 ppm random errors for 8-10 km altitudes and ~30 sec averaging times.

For the July 2010 ASCENDS campaigns we flew the lidar on the NASA DC-8 and made measurements of CO2 column absorption during longer flights over Railroad Valley NV, the Pacific Ocean and over Lamont OK. Analysis of the 2010 CO2 measurements shows the expected ~linear change of DOD with altitude. For measurements at altitudes > 6 km the random errors were 0.3 ppm for 80 sec averaging times. Details of the flight measurements and analysis will be described.

Presentation Type:  Poster

Session:  Coupled Processes at Land-Atmosphere-Ocean Interfaces   (Mon 4:00 PM)

Associated Project(s): 

• Related Activity

Poster Location ID: 73