HR: 0800h
AN: A51C-0786    [Abstracts]
TI: Demonstration of a Modulated Fiber Laser Based Sensor for Measurement of Lower Tropospheric Column Carbon Dioxide Mixing Ratios
AU: Browell, E V
EM: Edward.V.Browell@nasa.gov
AF: NASA Langley Research Center, Atmospheric Sciences, MS-401A, Hampton, VA 23681-2199 United States
AU: Choi, Y
EM: Y.Choi@larc.nasa.gov
AF: NASA Langley Research Center, Atmospheric Sciences, MS-401A, Hampton, VA 23681-2199 United States
AU: Dobbs, M E
EM: Mike.Dobbs@itt.com
AF: ITT Industries, Space Systems Division, 1919 West Cook Road, MS-648, Fort Wayne, IN 46801 United States
AU: Ismail, S
EM: Syed.Ismail-1@nasa.gov
AF: NASA Langley Research Center, Atmospheric Sciences, MS-401A, Hampton, VA 23681-2199 United States
AU: Moore, B
EM: B.Moore@unh.edu
AF: University of New Hampshire, Institute for the Study of Earth, Oceans, and Space, Morse Hall Suite 305, Durham, NH 03824 United States
AU: * Sharp, W E
EM: William.Sharp@itt.com
AF: ITT Industries, Space Systems Division, 1919 West Cook Road, MS-648, Fort Wayne, IN 46801 United States
AB: A unique, multi-frequency single beam, laser absorption spectroscopy system for space-based measurements of carbon dioxide (CO$_{2}$) mixing ratios in the troposphere is described. This system utilizes a low power, sinusoidally modulated continuous wave (CW) telecom laser system at 1.57 $\mu$m with lock-in detection of the received signal coming from the high gain HgCdTe avalanche photodiode (APD) detector. This system differs substantially from a standard pulsed, high energy Differential Absorption Lidar (DIAL) system. As a consequence, a low power, small, light weight, highly reliable system is fielded where the large signal-to-noise ratio (SNR) of the on-line-to-off-line (on-off) ratio of CO$_{2}$ absorption lines is achieved by signal processing. Results are reported on ground and airborne testing of this system. This testing was done in concert with known quantities of CO$_{2}$ in a laboratory gas absorption cell where SNRs of the on-off ratio in excess of 1000 were obtained. The field data were obtained in conjunction with the in-situ measurements of temperature, pressure, relative humidity, and CO$_{2}$. For the 0.5 to 2 km paths used in the horizontal testing, turbulence was the dominant noise factor. The airborne testing included an in-situ determination of CO$_{2}$ by a high-precision LI-COR instrument (0.1 ppm) along with separate temperature and pressure measurements. The flights were over the Department of Energy's Atmospheric Radiation Measurement Central Facility (ARM-CF) site. Two spiral profiles above the ARM-CF were accomplished along with overpasses at 10.6 km and 7.6 km. The atmospheric data and airborne remote and in-situ CO$_{2}$ measurements were used in the data analysis. The data collected from these tests have enabled the validation of an end-to-end instrument performance model, which is being used to support design studies of future airborne and space-based CW CO$_{2}$ DIAL systems.
DE: 1694 Instruments and techniques
DE: 0322 Constituent sources and sinks
DE: 0365 Troposphere--composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting