Evaluation of aerosol number concentrations from CALIPSO with ATom airborne in situ measurements

Abstract. The present study aims to evaluate the available aerosol number concentration (ANC) retrieval algorithms for spaceborne lidar CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) aboard CALIPSO and Infrared Pathfinder Satellite Observation) satellite airborne in situ measurements from ATom (Atmospheric Tomography Mission) campaign. We used HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory model) match both space identified 53 cases that were suitable comparison. Since data include dry extinction coefficient, we kappa parameterization adjust ambient conditions. As datasets have a different vertical resolution, regrid them uniform height bins of 240 m surface 5 km. On comparing coefficients, found reasonable agreement between Spearman's correlation coefficient 0.715. Disagreement was mostly retrievals above 3 km altitude. Thus, compare ANC, which may vary by orders magnitude time, further limit only select those CALIOP-derived is within ±50 % measurements. This additional filter increases probability same air parcel. altitude qualify constraint are estimate ANC radius >50 nm (n50,dry) >250 (n250,dry). POLIPHON (Polarization Photometer Networking) OMCAM (Optical Modelling Aerosol Microphysics) n50,dry n250,dry. estimates n250,dry be good measurements, 0.829 0.47, root mean square error (RMSE) 234 13 cm−3, bias −97 4 respectively. also 0.823 0.463, RMSE 247 44 However, OMCAM-estimated about an order less than marine-dominated cases. propose modification algorithm using AERONET-based marine model. With updated algorithm, agrees well Such concurrence satellite-derived independent emboldens use studying aerosol–cloud interactions.