Alternative Approach for Satellite Cloud Classification: Edge Gradient Application

Figure 1

Edge distribution among the different cloud types. 1: cirrus, 2: cirrostratus, 3: deep convection, 4: altocumulus, 5: altostratus, 6: nimbostratus, 7: cumulus, 8: stratocumulus, and 9: stratus. The graph shows that the cirrus, altocumulus, and cumulus clouds are more likely to have edges than the other types of clouds. This histogram is based on NOAA-AVHRR CTT satellite images of the Globe at a spatial resolution of 0.5 degree. The gradients from which the cloud types are derived are associated with the corresponding areas of cloud top pressure images and matched with the cloud type classification map of a commonly used method in cloud remote sensing, the ISCCP method (based on the cloud optical depth and the cloud top pressure). The more edges exist in a specific area, the more the cloud encountered is structured.