差分吸收激光雷达探测大气CO_2精度分析

为减小距离差分吸收激光雷达探测大气CO2浓度的探测误差,理论分析了探测精度,对差分吸收探测系统误差进行了数值分析,对基于1.6 μm光纤激光器相干探测CO2系统进行了仿真计算.结果表明:差分吸收截面越大,空间分辨率越低,回波信噪比越高,气体浓度的探测误差越小.当大气CO2的差分吸收光学厚度т为0.55时,相干探测系统具有最小误差变化百分比,此时探测精度最高.随着探测高度增大, 1.6 μm光纤激光相干探测系统精度逐渐降低,在1 km高度以内可以探测到34 ppm的大气CO2变化.

Accuracy Analysis of Differential Absorption Lidar for Detecting Atmospheric CO_2

In order to reduce the error of range differential absorption lidar for detecting atmospheric CO2,theory of detection accuracy is analyzed and the error of differential absorption detection system is simulated.Based on 1.6 μm optical fiber laser, the accuracy of coherent system is calculated. Results show that the signal to noise ratio of echo is higher and error of gas concentration is lower when the differential absorption cross section gets bigger and the spatial resolution gets worse. If the differential optical depth of CO2 is equal to 0.55, the percent variation of error is the least and the accuracy is the best. With the height increasing, the accuracy of 1.6 μm optical fiber laser coherent detection system is decreasing. When the height is lower than 1 km, the atmospheric CO2 variation of 34 ppm can be detected.