Abstract:Based on the NOAA/AVHRR multi-spectral data, the effective radius of particles on the fog top was retrieved via the reflectance of channel centered at 3.7μm , and the microphysical properties of fogs were displayed and analyzed by means of composite RGB images. Three cases of cold fog, warm fog and oceanic advection fog in 2006 are quantitatively analyzed by means of microphysical parameters on fog top, such as visible reflectance, brightness temperature and fog drop effective radius. The composite RGB images show that the fog has even grains, smooth top and clear edge; the visible reflectance of three kinds of fog are among 30%-60% and the thicker fog has larger reflectance and small effective radius with stable value between 7 and 10 μm; in comparison with layer cloud, fog has higher bright temperature and oceanic advection fog has bright temperature higher than surrounding ocean surface. The retrieval effective radius is close to the value of surface observation, which indicates that the retrieved results are reasonable.