Evaluation of the CALIPSO Satellite Cloud Sub-Type Classification Product over a Global Distribution

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Sunday, 17 January 2010
Exhibit Hall B2 (GWCC)
Christopher J. Slocum, NASA/LRC DEVELOP National Program, University Park, PA

To evaluate the accuracy of the cloud sub-type algorithm developed to process raw data from NASA's Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations satellite (CALIPSO) and to determine applicability to cloud climatology. The Cloud-Aerosol Lidar with Orthogonal Polarization instrument (CALIOP) aboard CALIPSO produces vertical profiles of backscatter intensity from cloud droplets and aerosols in the atmosphere. The CALIPSO cloud sub-type algorithm determines cloud genera (cirrus, altostratus, cumulus, etc.) from the profile information specifically: cloud top pressure, cloud fraction (ratio of 1km profiles with clouds below the low cloud threshold to the total number of 1km profiles, all within an 80km segment), and transmissivity/opacity. To analyze the information derived by the CALIPSO algorithm, a new algorithm was created to generate distributions of global and fractional coverages of cloud genera, distributions of cloud types as a function of cloud top temperature (CLTT) and cloud top pressure (CLTP), and comparisons of the diurnal cycles for cloud coverages. The results obtained from the cloud sub-type algorithm were compared to the International Satellite Cloud Climatology Project (ISCCP) which utilizes a different remote sensing technique to derive cloud genera. This study found that the cloud sub-type algorithm results from CALIPSO strongly correlated to the ISCCP and can be used in cloud climatology applications.