The effect of high cloud variability on ice water path characterization

Cloud InfraRed Radiometer for UnesS* (CIRRUS) mission proposes installing a far-IR radiometer on the International Space Station (ISS). This instrument will be used to retrieve cloud Ice Water Path (IWP) and median particle diameter. Accurate characterization of the mean cloud properties is dependent on a solid understanding of how the ISS orbit and high cloud variability affect the property averages. The ISS orbit has the advantage that the overpasses vary throughout the day in a pattern that repeats every 36 days. The temporal and spatial variability in the presence of high clouds adds a large number of discontinuities to any time series of cloud microphysical property measurements. The ISS orbit and the discontinuities make it necessary to average over long time scales or large spatial areas to effectively characterize the mean cloud properties. Quantification of the spatial sizes and time scales needed to produce accurate means will help establish the capabilities of the CIRRUS instrument. We will be using 14 months of International Satellite Cloud Climatology (ISCCP) data and 26 months of high cloud data derived from the Geostationary Operational Environmental Satellite (GOES) sounder to simulate the CIRRUS IWP measurements.

* University Earth System Science project (UnESS)