Evaluation of the international satellite cloud climatology project simulator using data from the atmospheric radiation measurement Southern Great Plains facility in Oklahoma

Clouds are a vital part of the earth's climate system. They interact with incoming solar and outgoing infrared radiation to both cool and warm the planet. How clouds will change and modify the earth's climate in the future is still uncertain. General circulation models (GCMs) are used to better understand how clouds will affect future climates. Global satellite observational systems, like the International Satellite Cloud Climatology Program (ISCCP) and a layer bispectral threshold method (LBTM), are often used for comparisons with GCMs to test how accurately model parameterizations are producing clouds. However, model output is not directly comparable to satellite retrievals, and thus an ISCCP simulator has been developed to take predicted cloud properties from the model and mimic how the ISCCP algorithm would interpret the atmosphere. The primary goal of this study was to use data from the Atmospheric Radiation Measurement site in Oklahoma to critically evaluate the ISCCP simulator. Our findings show that overall the simulator performs reasonably well. However, the simulator does not seem to produce the large occurrences of thin mid-level clouds found in ISCCP retrievals. There seem to be two specific modes of disagreement present. We have identified potential problems in the simulator and the satellite retrievals that could account for these disagreements. However, further investigation is required to understand these issues more completely.