2008-10-01: Evaluation of satellite cloud phase retrieval methods from SEVIRI data

The thermodynamic phase of clouds plays an important role in the Earth's energy balance, as water clouds reflect incoming shortwave radiation back to space and ice clouds absorb and emit terrestrial radiation back to the surface. Geostationary satellite instruments, such as SEVIRI onboard METEOSAT-8 and -9, are capable of providing cloud phase information at both high temporal and spatial resolution. Wolters et al. [2008] evaluated three methods for cloud phase determination from SEVIRI data against collocated and synchronized cloud phase observations from lidar and cloud radar at Cabauw, The Netherlands.
It was found that all methods are well suitable for detection of both the annual and diurnal cycle of cloud phase, although cloud phase based on a cloud-top temperature threshold of 260 K underestimates the amount of water clouds during mid-latitude winter.
Diurnal cycle of water cloud (left panel) and ice cloud (right panel) occurrence frequency obtained from SEVIRI methods (non-solid lines) and collocated and synchronized observations from cloud radar and lidar at Cabauw (solid line), The Netherlands for May - August 2004. The grey histograms denote the number of observations collected for each hour.