85th AMS Annual Meeting

Monday, 10 January 2005: 9:30 AM
Development of a ground-based 2-micron DIAL system for atmospheric boundary layer and climate studies
Syed Ismail, NASA/LRC, Hampton, VA; and G. J. Koch, U. N. Singh, and K. J. Davis
Poster PDF (283.7 kB)
Data density, both in time and space, remains a primary limit to our ability to derive regional terrestrial CO2 fluxes. Vertical differences in the CO2 mixing ratio profile can be large, especially between the atmospheric boundary layer (ABL) and the free troposphere. Mixing between the ABL and the free troposphere is periodically vigorous (e.g. fronts, cloud convection) and can have a strong impact on the ABL CO2 budget. Data from a continuous monitoring tropospheric CO2 mixing ratio profiling system and the continental CO2 mixing ratio measurement network that is being implemented in North America could be used to obtain daily to monthly net ecosystem-atmosphere exchange (NEE).

Active remote sensing capability for continuous CO2 profiling in the atmosphere has already been demonstrated at NASA Langley Research Center using the Differential Absorption Lidar (DIAL) technique in the 2-micron region. This followed the development of high power, pulsed, narrow bandwidth, tunable lasers with the ability to lock onto optimum absorption lines for the measurement of CO2 profiles. We plan to enhance the capability of the existing CO2 DIAL system to enable improved tropospheric profiling of CO2. The measurement precision of the system will be enhanced using recently acquired high quantum efficiency, high-gain, and low-noise detectors and a large collection area telescope. We plan to integrate the ground-based DIAL system and evaluate and optimize its performance. Well-calibrated, in situ infrared gas analyzers will be used to evaluate the DIAL system. We anticipate that the DIAL system will achieve 1% (3 ppm) absolute accuracy and 0.5% (1.5 ppm) precision while measuring CO2 mixing ratios with 1 km vertical resolution and 30 minute temporal resolution up to range of 4 to 5 km. This precision will readily resolve the daily ABL free troposphere mixing ratio difference.

Supplementary URL: