Tropical Ice Cloud Statistics from Aqua MODIS Observations

The Moderate-resolution Imaging Spectroradiometers (MODIS) on NASA's Terra and Aqua platforms offer valuable observations of the earth-atmosphere system, facilitating significant research in the atmospheric sciences. Specifically, the implementation of the 1.375-µm channel, located in a water vapor absorption band, allows for exclusive investigations of ice clouds (e.g., cirrus clouds). In this study, we perform a statistical analysis of tropical ice cloud optical depth fields using the Aqua MODIS daily global dataset. Daily ice cloud optical depth values are inferred from three years (Sep 2002 to Aug 2005) of Aqua MODIS cirrus reflectance using a look-up table approach. Simple statistics, such as seasonal means and variances, are used to establish the general trends in the ice cloud optical depth fields over the tropics. Time series analyses of the daily optical depth over various locations are performed, giving some insight into the persistence and movement of tropical ice cloud systems.