Evaluating CALIPSO's 532 nm lidar ratio selection algorithm using AERONET sun photometers in Brazil

Autor(es)

Lopes, F. J. S. ^{[1, 2]} ; Landulfo, E. ^[2] ; Vaughan, M. A. ^[3]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geophys & Atmospher Sci IAG, Sao Paulo - Brazil

^[2] Nucl & Energy Res Inst IPEN CNEN, Ctr Lasers & Applicat, Sao Paulo - Brazil

^[3] NASA, Langley Res Ctr, Hampton, VA 23681 - USA

• Tipo de documento: Artigo Científico
• Fonte: Atmospheric Measurement Techniques; v. 6, n. 11, p. 3281-3299, 2013.
• Citações Web of Science: 20

Resumo

Since the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite first began probing the Earth's atmosphere on 13 June 2006, several research groups dedicated to investigating the atmosphere's optical properties have conducted measurement campaigns to validate the CALIPSO data products. Recently, in order to address the lack of CALIPSO validation studies in the Southern Hemisphere, and especially the South American continent, the Lasers Environmental Applications Research Group at Brazil's Nuclear and Energy Research Institute (IPEN) initiated efforts to assess CALIPSO's aerosol lidar ratio estimates using the AERONET sun photometers installed at five different locations in Brazil. In this study we develop a validation methodology to evaluate the accuracy of the modeled values of the lidar ratios used by the CALIPSO extinction algorithms. We recognize that the quality of any comparisons between satellite and ground-based measurements depends on the degree to which the instruments are collocated, and that even selecting the best spatial and temporal matches does not provide an unequivocal guarantee that both instruments are measuring the same air mass. The validation methodology presented in this study therefore applies backward and forward air mass trajectories in order to obtain the best possible match between the air masses sampled by the satellite and the ground-based instruments, and thus reduces the uncertainties associated with aerosol air mass variations. Quantitative comparisons of lidar ratios determined from the combination of AERONET optical depth measurements and CALIOP integrated attenuated backscatter measurements show good agreement with the model values assigned by the CALIOP algorithm. These comparisons yield a mean percentage difference of -1.5% +/- 24 %. This result confirms the accuracy in the lidar ratio estimates provided by the CALIOP algorithms over Brazil to within an uncertainty range of no more than 30 %. (AU)

• Processo FAPESP: 13/02357-3 - Assessment of the CALIPSO LIDAR 532 nm version 3 LIDAR ratio models using a ground-based LIDAR and AERONET sun photometers in Brazil
• Beneficiário: Fábio Juliano da Silva Lopes
• Modalidade de apoio: Auxílio à Pesquisa - Publicações científicas - Artigo
• Processo FAPESP: 08/58104-8 - Narrowing the uncertainties on aerosol and climate changes in São Paulo State: NUANCES-SPS
• Beneficiário: Maria de Fátima Andrade
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático
• Processo FAPESP: 11/07475-9 - Visita do Dr. Mark A. Vaughan: aperfeiçoamento do algoritmo de análises dos dados LIDAR e dados do satélite CALIPSO
• Beneficiário: Eduardo Landulfo
• Modalidade de apoio: Auxílio à Pesquisa - Pesquisador Visitante - Internacional
• Processo FAPESP: 11/14365-5 - Aplicação dos dados de perfil vertical medidos por um sistema Lidar e pelo satélite CALIPSO no mapeamento da distribuição dos aerossóis na região metropolitana e no estado de São Paulo
• Beneficiário: Fábio Juliano da Silva Lopes
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado