Analysis of three years of ice cloud properties over the tropics from MODIS

Three years (September 2002 through August 2005) of the Moderate Resolution Imaging Spectroradiometer (MODIS) level-3 cloud products (archive product names MOD08_D3 based Terra MODIS measurements and MYD08_D3 based on Aqua MODIS measurements) from the Collection 4 processing stream are used to investigate cloud fraction, optical thickness, effective particle size, cloud-top temperature, and effective emissivity (cloud fraction multiplied by cloud emissivity) of ice clouds over the tropics. Ice clouds are further classified as cirrus, cirrostratus, and deep convective clouds on the basis of the International Satellite Cloud Climatology Project (ISCCP) classification scheme. A large portion of ice clouds are cirrostratus clouds, contributing over 50% ice cloud fractions and having similar values of optical thickness, cloud-top temperature, effective size, and emissivity in comparison with those for ice clouds . The geographical distributions of MODIS ice cloud fractions and the ISCCP-classification-scheme-based cirrus, cirrostratus, and deep convective clouds have similar patterns. The major concentrations of those ice clouds are over the Intertropical Convergence Zone (ITCZ), the South Pacific Convergence Zone (SPCZ), tropical Africa, Indian Ocean, and tropical and South America. The cloud fractions have a distinct seasonal south shifting from northern hemisphere summer to winter. Prominent ocean-land, morning-afternoon, and summer-winter contrasts are noticed for cloud fractions, top temperatures, optical thicknesses, effective sizes, and effective emissivities of ice clouds and classified cirrus, cirrostratus, and deep convective clouds.