Comparing sources of variability in cloud-characterized HIRS radiances

Abstract:

The difficulty of modeling and observing cloud processes continue to stymie efforts at tracking and projecting cloud behavior in a changing climate. While robust determination of the global cloud feedback remains elusive, the ~30-year radiance record from High Resolution Infrared Radiation Sounders (HIRS) and the corresponding visible imagery database may enable the constraint of individual components of the cloud feedback. Specifically, signals in region- and cloud-type-specific infrared radiances may be detectable with some significance.

Using nearly simultaneous nadir cloud type information from the Clouds from AVHRR Extended (CLAVR-x) dataset, we analyze sources of variability in cloud-characterized HIRS radiances. Inter-satellite biases are large enough to hamper the determination not just of long-term trends, but also of diurnal and interannual variability. However, changes in variability, rather than the mean, may be detectable with the current state of instrumentation. Characterizing cloud variability is expected to shed light on physical climate processes.