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An improved algorithm for retrieving surface downwelling longwave radiation from satellite measurements
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Wilber, Anne C. Zhou, Yaping Gupta, Shashi K. Kratz, David P. Cess, Robert D. |
| Copyright Year | 2007 |
| Description | Zhou and Cess [2001] developed an algorithm for retrieving surface downwelling longwave radiation (SDLW) based upon detailed studies using radiative transfer model calculations and surface radiometric measurements. Their algorithm linked clear sky SDLW with surface upwelling longwave flux and column precipitable water vapor. For cloudy sky cases, they used cloud liquid water path as an additional parameter to account for the effects of clouds. Despite the simplicity of their algorithm, it performed very well for most geographical regions except for those regions where the atmospheric conditions near the surface tend to be extremely cold and dry. Systematic errors were also found for scenes that were covered with ice clouds. An improved version of the algorithm prevents the large errors in the SDLW at low water vapor amounts by taking into account that under such conditions the SDLW and water vapor amount are nearly linear in their relationship. The new algorithm also utilizes cloud fraction and cloud liquid and ice water paths available from the Cloud and the Earth's Radiant Energy System (CERES) single scanner footprint (SSF) product to separately compute the clear and cloudy portions of the fluxes. The new algorithm has been validated against surface measurements at 29 stations around the globe for Terra and Aqua satellites. The results show significant improvement over the original version. The revised Zhou-Cess algorithm is also slightly better or comparable to more sophisticated algorithms currently implemented in the CERES processing and will be incorporated as one of the CERES empirical surface radiation algorithms. |
| File Size | 347528 |
| Page Count | 34 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20080000844 |
| Archival Resource Key | ark:/13960/t3fz2800c |
| Language | English |
| Publisher Date | 2007-01-01 |
| Access Restriction | Open |
| Subject Keyword | Meteorology And Climatology Bias Satellite Observation Earth Sciences Radiant Flux Density Water Vapor Ice Clouds Long Wave Radiation Terra Spacecraft Upwelling Water Precipitation Algorithms Systematic Errors Clouds Meteorology Modis Radiometry Radiative Transfer Surface Radiation Budget Project Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
