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Comparison of satellite based cloud retrieval methods for cirrus and stratocumulus
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Parker, Lindsay Wielicki, Bruce A. |
| Copyright Year | 1990 |
| Description | One difficulty in using satellite remote sensing data is the spatial variability of cloud properties on scales smaller than most meteorological satellite fields of view (approx. 4 to 8 km). The variation is examined of satellite derived cloud cover as a function of the satellite sensor spatial resolution for seven cloud cover retrieval methods: (1) Reflectance threshold; (2) Temperature threshold; (3) ISCCP; (4) HBTM (Hybrid Bispectral Threshold Method); (5) NCLE; (6) Spatial coherence; and (7) Functional Box Counting. The first two methods are simple single spectral thresholds which specify a satellite pixel as cloud filled if the measured reflectance is greater than the threshold, or if the measured equivalent blackbody temperature is less than the threshold. The next three methods are bispectral, using one visible wavelength window channel and one thermal infrared wavelength window. The final two algorithms rely on the spatial variability within the cloud field to determine cloud cover. Spatial coherence assumes only that the cloud field occurs in a single layer and that the clouds are optically thick in the infrared window. LANDSAT Thematic Mapper (TM) data is used to test the spatial resolution dependence of the cloud algorithms. The ISCCP bispectral threshold applied to the full resolution data is used as the reference or truth cloud cover, after which the retrieval methods are applied to the spatial resolutions. Studies of the fraction of pixels in the scene at cloud edge, and of the profile of reflectance and temperature near cloud edges indicate an uncertainty in the reference cloud fraction of 1 to 5 percent. |
| File Size | 377552 |
| Page Count | 6 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19900018952 |
| Archival Resource Key | ark:/13960/t17m55x6d |
| Language | English |
| Publisher Date | 1990-07-01 |
| Access Restriction | Open |
| Subject Keyword | Meteorology And Climatology Climatology Cirrus Clouds Black Body Radiation Satellite Observation Stratocumulus Clouds Infrared Spectra Infrared Windows Remote Sensing Cloud Cover Algorithms Atmospheric Temperature Cloud Physics Brightness Temperature Thematic Mappers Landsat Spatial Resolution Reflectance Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
