2009 Annual Report - NASA Airborne Science Program

measurements. The flight patterns were at altitudes
from 3-8 km centered above the ARM site. The
increased CO2 absorptions at higher altitudes were
evident in all flights.
The flights were also coordinated with investigators
at LBNL, who flew an in-situ CO2 sensor on a
Cessna aircraft inside the CO2 sounder’s flight
pattern. These yielded 2 profiles of CO2 from 5 km
to the surface for comparisons. Data analyses showed
agreement to better than 2% (6 ppm).
Goddard’s CO2 Laser Sounder Team successfully
completed an extensive set of airborne
measurements with its lidar instrument in summer
2009. The lidar measures the optical absorption
of atmospheric CO2 in the nadir column from
the aircraft to the surface by stepping a pulsed
laser transmitter in wavelength across the 1572.33
nm CO2 absorption line. The time resolved laser
backscatter and CO2 absorption and line shape are
measured by a photon counting receiver. Several
instrument improvements were made since the lidar
was flown in December 2008.
The instrument was installed on the NASA Glenn
Research Center’s Lear-25 aircraft in July 2009. Nine
science flights were flown over Nebraska, eastern
Illinois, the DOE ARM site near Lamont OK,
eastern North Carolina and over the Chesapeake
Bay and the Eastern Shore of Virginia. Each flight
was just over 2 hours long and was flown with
altitudes stepped from 3-13 km. The instrument
worked well and CO2 line shapes and absorptions vs.
altitude were measured on all flights. Data analysis is
underway.
The Goddard airborne CO2 Sounder team is led
by Jim Abshire (PI). The CO2 Sounder activity is a
precursor for the NASA ASCENDS mission, and
is supported by ASCENDS funding, and the ESTO
IIP and the Goddard IRAD programs.
Figures 40 and 41:
Pulsed airborne version of CO2 Sounder Instrument on the NASA Glenn
Lear-25.
42