Abstract :
A new algorithm for extracting the backscattering coefficient profiles from elastic and inelastic lidar signals is presented. It re-formulate the Raman lidar equation, provided by the interaction of the laser light with the atmospheric nitrogen, in order to obtain the exponential of the integral of the extinction coefficient at the elastic wavelength instead of the extinction coefficient profile, as it is traditionally made, assuming the usual wavelength-dependent relationship between the Raman and Elastic extinction coefficients, and then substitutes that quantity into the elastic lidar equation to obtain the backscattering profile. That circumvents the calculation of the derivative of the noisy inelastic lidar signal with the main advantage of the extraction of backscattering coefficient profiles, one of the final products, without requiring any smoothing or filtering of the original signals. Several examples of the new method applied to profiles obtained with the CIEMAT lidar system, located in Madrid (SPAIN), are analyzed and the results are compared with other algorithm calculations. In conclusion, an improvement of the reliability and accuracy of the retrieved data was observed in the cases analyzed.
Keywords :
Raman spectra; atmospheric composition; atmospheric optics; atmospheric techniques; inverse problems; nitrogen; optical radar; CIEMAT lidar system; N; Raman lidar; atmospheric nitrogen; backscattering coefficient profiles; elastic lidar equation; elastic wavelength; extinction coefficient; inelastic lidar signals; inelastic signal; inversion algorithm; noisy inelastic lidar signal; Algorithm design and analysis; Atmospheric waves; Backscatter; Extinction coefficients; Filtering; Information retrieval; Integral equations; Laser radar; Nitrogen; Smoothing methods; Algorithm; Inversion; LIDAR; component;
