Improving CO2 Concentration Profile Measurements From a Ground-Based CO2-DIAL Through Conditional Adjustment

Ground-based differential absorption lidar (DIAL) can measure vertical CO2 concentration profiles in the troposphere. Here, we propose a method of improving the accuracy and precision of CO2 concentration profiles measurements. This method combines a conditional adjustment with Chebyshev fitting to reduce the error of the retrieved results in view of the received signal around the atmospheric boundary layer (ABL) with a high signal-to-noise ratio (SNR). Simulation experiments verified the effectiveness of this method. The accuracy of CO2 concentration profiles can be improved larger than 83.4% when compared with that via traditional methods, and the standard deviation of the measured CO2 concentration profiles calculated by our method was reduced by approximately 0.43-22.51 ppm when compared with the results calculated by traditional methods. Two real cases in different locations were also examined with the proposed technique. The results indicated the applicability of our method in measuring other trace gases by using DIAL.