A MODIS simulator and matching dataset for the evaluation of clouds in climate models

Abstract

The MODIS instrument flying on the Terra and Aqua EOS platforms have now obtained a decade-long record of observations of clouds and aerosols. These observations complement the 30 year ISCCP record by providing new information (particle size estimates), refinements of existing observations (cloud properties discriminated by phase), and alternative estimates (cloud top pressure determined using CO2 slicing instead of infrared brightness temperatures). Here we describe a software package and specially-produced data set developed for using MODIS observations of cloud properties to evaluation climate models. We describe the "MODIS simulator," which produces estimates of cloud occurrence, optical thickness, particle size, and clod top pressure based on stochastically-generated subcolumns. We compare cloud retrievals from ISCCP and MODIS, describe a data set developed estpecially for model evaluation, and show results obtained by using the simulator with the GFDL climate model AM2, focussing on the differences relative to ISCCP.