A comparison of GOES-8 imagery with cloud-top penetrations by a research aircraft

Various studies have shown that it is possible to extract a variety of information about the locations, temperature, and microphysical properties of cloud tops from GOES-8 imager data. The visible channel can provide information about the water content, concentration of cloud particles, and cloud depth. The shortwave IR channel has shown promise in detecting both cloud phase and particle sizes, while the long wave IR channel is useful in determining cloud top temperatures. Since the GOES-8 imagery has high temporal and spatial resolution, this cloud information can be quite valuable for monitoring clouds that may cause aircraft icing. In recent years, several algorithms have used GOES-8 measurements to identify supercooled liquid water at cloud tops.

During the winters of 1997 and 1998, the NASA-Glenn Twin Otter research aircraft sampled a variety of subfreezing clouds over the Great Lakes region. In this study, microphysical probe and state-parameter data from Twin Otter cloud top penetrations are examined and broken into several categories depending on cloud top temperature, cloud phase, liquid water content, particle concentration, and particle size. The aircraft and GOES-8 data are objectively compared to test for cloud top temperature accuracy and the ability of certain channels to differentiate between various microphysical properties at cloud top. Results will provide new information regarding the use of GOES-8 data for in-flight icing detection.