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Study on Influences of Atmospheric Factors on Vertical mboxCO2 Profile Retrieving From Ground-Based DIAL at 1.6 μm

By: Han, G.; Xiang, Z.; Ma, X.; Lin, H.; Gong, W.;

2015 / IEEE

Description

This item from - IEEE Transaction - Geoscience - Differential absorption lidar (DIAL) is widely accepted as the most promising remote sensing means to map the global mboxCO2 concentrations. Nevertheless, diurnal variations and vertical distributions of atmospheric mboxCO2 cannot be obtained by satellite-borne and airborne measurements. Ground-based DIAL systems are developed to fill this gap, as well as serve as validations for satellite-borne measurements. Atmospheric factors play significant roles in obtaining accurate range-resolved measurements of mboxXmathrmCO2 . However, the influence of atmospheric factors on the performance of a ground-based DIAL system aiming at mboxCO2 measurements has not been dedicatedly discussed yet. The pressure, temperature, and water vapor of the atmosphere have been taken into consideration for performance evaluation after preselection of absorption lines around 1.6 μm in this paper. In addition, errors caused by variations of aerosols have also been analyzed by using theoretical simulations and real measurements. We found that biases caused by temperature and pressure uncertainties were 0.11–0.45 ppm/K and 0.39 ppm/hPa, respectively, if the central wavelength was utilized as the online wavelength. In addition, the water vapor effect could be neglected by cautious selection of online and offline wavelength. Finally, if the online and offline wavelengths were transmitted alternatively, the temporal and range resolutions have to be determined very carefully to balance the signal-to-noise ratio of acquired data and tolerable errors derived from variations of aerosols. A variable range resolution is recommended for mboxCO2 measurements at different altitudes to fulfill the target precision.