The AMSU's 89-GHz channel (85 GHz for SSM/I) is key to the retrieval of rain rate over both ocean and land due to the sensitivity of scattering by ice. In this image from 9 May 1999, the relatively dark or cold spots within the brighter areas are indicative of ice hydrometeors within the rain bands approaching the West Coast of the U.S. Dark spots in the imagery over North America may indicate ice particles and precipitation processes over land. Careful screening is required though, as surface snow and ice cover can produce signatures similar to those associated with ice particles in clouds.

Another 89-GHz image, this one over Alaska, clearly shows the signature associated with snow cover and sea ice. Retrieval of these parameters is discussed in more detail in the Products and Applications section under Surface Products.