Climatology of the aerosol extinction-to-backscatter ratio from sun-photometric measurements

• Published in: IEEE Transactions on Geoscience and Remote Sensing
• Main Authors: Baldasano Recio, José María, Pedrós, Roberto, Estallés, Víctor, Sicard, Michaël, Gómez Amo, Jose Luis, Utrillas, Maria Pilar, Martínez Lozano, José Antonio, Rocadenbosch Burillo, Francisco, Pérez, C.
• Other Authors: Universitat Politècnica de Catalunya. Departament de Projectes d'Enginyeria, Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions, Universitat Politècnica de Catalunya. RSLAB - Grup de Recerca en Teledetecció, Universitat Politècnica de Catalunya. MTA - Modelització i Tecnologia Ambiental
• Format: Article in Journal/Newspaper
• Language: English
• Published: IEEE Press. Institute of Electrical and Electronics Engineers 2010
• Subjects: Àrees temàtiques de la UPC::Enginyeria de la telecomunicació; Aerosols; Sun-Photometric; Optical radar; Signal theory (Telecommunication); back trajectories; extinction-tobackscatter; Sun photometer; Senyal; Teoria del (Telecomunicació); Aerosol Robotic Network
• Online Access: http://hdl.handle.net/2117/10922; https://doi.org/10.1109/TGRS.2009.2027699

The elastic lidar equation contains two unknown atmospheric parameters, namely, the particulate optical extinction and backscatter coefficients, which are related through the lidar ratio (i.e., the particulate-extinction-to-backscatter ratio). So far, independent inversion of the lidar signal has been carried out by means of Raman lidars (usually limited to nighttime measurements), high-spectral-resolution lidars, or scanning elastic lidars under the assumption of a homogeneously vertically stratified atmosphere. In this paper, we present a procedure to obtain the lidar ratio at 532 nm by a combined Sunphotometer– aerosol-model inversion, where the viability of the solution is largely reinforced by assimilating categorized air-mass back-trajectory information. Thus, iterative lidar-ratio tuning to reconstruct the Sun-photometric aerosol optical depth (AOD) is additionally constrained by the air-mass back trajectories provided by the hybrid single-particle Lagrangian integratedtrajectory model. The retrieved lidar ratios are validated with inversions of lidar data based on the Klett–Fernald–Sasano algorithm and with the Aerosol Robotic Network (AERONET)- retrieved lidar ratios. The estimated lidar ratios concur with the AERONET-retrieved lidar ratios and with those of the well-known KFS inversion constrained with Sun-photometric AOD values and embedded single-scattering models. The proposed method can be applied to routinely extract climatological values of the lidar ratio using measurements of direct solar irradiance (more numerous than those of sky radiance). Postprint (published version)