Analysis of Global Cloud Imagery from Multiple Satellites

Synoptic images of the global cloud field have been created from infrared measurements taken aboard four geostationary and two polar-orbiting platforms simultaneously observing the earth. A series of spatial and temporal interpolations together with data reliability criteria are used to composite data from the individual satellites into synoptic images of the global cloud pattern. The composite Global Cloud Imagery (GCI) have a horizontal resolution of about half a degree and a temporal resolution of 3 h, providing an unprecedented view of the earth's cloud field. Each composite image represents a nearly instantaneous snapshot of the global cloud pattern. Collectively, the composite imagery resolve, on a global basis, most of the variability associated with organized convection, including several harmonics of the diurnal cycle. The dense and 3-dimensional nature of the GCI make them a formidable volume of information to treat in a practical and efficient manner. To facilitate analysis of global cloud behavior, the GCI has been constructed with certain homogeneous properties. In addition to synoptic coverage of the globe, data are spaced uniformly in longitude, latitude,and time, and contain no data voids. An interactive Image Analysis System (IAS) has been developed to investigate the space-time behavior of global cloud activity. In the IAS, data, hardware, and software are integrated into a single system capable of providing a variety of space-time covariance analyses. Because of its customized architecture and the homogeneous properties of the GCI, the IAS can perform such analyses on the 3-dimensional data with interactive speed. Statistical properties of cloud variability are presented along with other preliminary results derived from the GCI.