Scattering layer statistics from space borne GLAS observations
Cloud and aerosol layers detected by the space borne Geoscience Laser Altimeter System (GLAS) are used to derive statistics of clear and almost clear atmospheres. Such statistics are needed to evaluate the potential coverage of NASA’s forthcoming Orbital Carbon Observatory (OCO). The global fraction...
| Main Authors: | , , |
|---|---|
| Other Authors: | |
| Format: | Text |
| Language: | English |
| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.520.7042 http://www.gps.caltech.edu/~vijay/Papers/Aerosol/breon_glas.pdf |
| Summary: | Cloud and aerosol layers detected by the space borne Geoscience Laser Altimeter System (GLAS) are used to derive statistics of clear and almost clear atmospheres. Such statistics are needed to evaluate the potential coverage of NASA’s forthcoming Orbital Carbon Observatory (OCO). The global fraction of clear cases without aerosol or cloud is on the order of 15%, with large scale spatial structures that match similar results from passive sensors. The spatial distribution of almost clear atmospheres, defined to be those with optical thickness less than 0.2, is similar to that for clear atmospheres, with the global fraction approximately 20%. The mean altitude of these thin scattering layers is generally below one kilometer, indicating that they are composed mostly of boundary layer aerosol rather than elevated cloud. The spatial correlation function of clear cases is accurately reproduced by the analytical function F(d)=exp[-(d/d0) 0.5], where d0 is a correlation scale length. Between 60N and 60S, d0 shows little zonal variation and its average value is 321 km. Over the Arctic d0 falls to 244 km, but rises to 464 km over the Antarctic. |
|---|