Different strategies to retrieve aerosol properties at night-time with the GRASP algorithm

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Benavent Oltra, José Antonio, Casquero Vera, Juan Andrés, Pérez Ramírez, Daniel, Lyamani, H., Ortiz-Amezcua, Pablo, Guerrero Rascado, Juan Luis, Olmo Reyes, Francisco José, Alados Arboledas, Lucas
• Format: Article in Journal/Newspaper
• Language: English
• Published: European Geosciences Union 2019
• Subjects: Aerosol Robotic Network
• Online Access: http://hdl.handle.net/10481/58387; https://doi.org/10.5194/acp-19-14149-2019

This study evaluates the potential of the GRASP algorithm (Generalized Retrieval of Aerosol and Surface Properties) to retrieve continuous day-to-night aerosol properties, both column-integrated and vertically resolved. The study is focused on the evaluation of GRASP retrievals during an intense Saharan dust event that occurred during the Sierra Nevada Lidar aerOsol Profiling Experiment I (SLOPE I) field campaign. For daytime aerosol retrievals, we combined the measurements of the ground-based lidar from EARLINET (European Aerosol Research Lidar Network) station and sun–sky photometer from AERONET (Aerosol Robotic Network), both instruments co-located in Granada (Spain). However, for night-time retrievals three different combinations of active and passive remote-sensing measurements are proposed. The first scheme (N0) uses lidar night-time measurements in combination with the interpolation of sun–sky daytime measurements. The other two schemes combine lidar night-time measurements with nighttime aerosol optical depth obtained by lunar photometry either using intensive properties of the aerosol retrieved during sun–sky daytime measurements (N1) or using the Moon aureole radiance obtained by sky camera images (N2). This research has been supported by the European Union through the H2020 programme (ACTRIS-2, grant no. 654109) and the Spanish Ministry of Economy and Competitiveness (projects CMT2015-66742-R, CGL2016-81092- R, CGL2017-85344-R, RTI2018-097864-B-I00 and CGL2017- 90884-REDT).