Verification of Satellite-Derived Cloud Properties Using Cloud Observations from Students and the General Public

The Students' Cloud Observations On-Line (S'COOL) Project engages both students and the general public to assist in the validation of cloud properties derived for NASA's Cloud and the Earth's Radiant Energy System (CERES) mission. One of the objectives of the CERES mission is to study how the presence of clouds alters the Earth's radiation budget and impacts climate. S'COOL participants assist the CERES mission by reporting similar cloud properties to those retrieved for CERES such as cloud cover, cloud height, cloud layering, and cloud visual opacity within a +/- 15 minute time frame of the instrument's overpass. Since the initiation of S'COOL in 1997, the project has obtained over 128,000 ground observations from over 4,800 schools across the globe. From this substantial dataset, comparisons can be made between ground-based observations and satellite derived cloud properties. An additional benefit of S'COOL program is to encourage participants, i.e. “Citizen Scientists”, to regularly study clouds and how they evolve from day to day in relation to observed weather conditions.

This presentation will report on comparisons of S'COOL observations to both CERES derived cloud properties and other cloud retrieval methods. Disagreements between cloud properties reported by S'COOL and CERES can be used to highlight possible shortcomings in CERES' detection methods, while agreements can facilitate their validation in an alternative way relative to traditional validation approaches using CALIPSO and CloudSat. In addition to the CERES and S'COOL co-locations, a subset of these S'COOL matches are co-located with the CALIPSO and CloudSat observations. The active radar and lidar instruments onboard these satellites provide a vertical profile of clouds that can be used as verification for S'COOL reports. Lastly, the same analyses conducted for S'COOL observations will be conducted for the NASA/NSF GLOBE Program, another community of ground-based cloud observers. The results from S'COOL and GLOBE will be compared against one another to study how well they correlate. In total, these comparisons will provide ground-based validation of CERES cloud properties and an understanding of the utility of ground-based human cloud observations for verifying CERES and other polar-orbiting or geostationary satellite-derived cloud properties.