Multilayer Cloud Detection with the MODIS Near-Infrared Water Vapor Absorption Band

• Published in: Journal of applied meteorology and climatology Vol. 49; no. 11; pp. 2315 - 2333
• Main Authors: Wind, Galina, Platnick, Steven, King, Michael D., Hubanks, Paul A., Pavolonis, Michael J., Heidinger, Andrew K., Yang, Ping, Baum, Bryan A.
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.11.2010
• Subjects: Absorption bands; Absorption spectra; Algorithms; Anvil clouds; Atmospheric models; Atmospherics; Carbon dioxide; Cirrus clouds; Cloud detection; Cloud models; Cloud properties; Clouds; Data collection; Detection; Earth Observing System (EOS); Earth, ocean, space; Exact sciences and technology; External geophysics; Ice clouds; Liquids; Mathematical models; Meteorology; MODIS; Monolayers; Multilayers; Near infrared radiation; Optical thickness; Precipitable water; Sea water; Spacecraft; Spectroradiometers; Statistical analysis; Statistical methods; Thermodynamics; Water vapor; Water vapour; Water cloud; algorithms; models; Terra satellite; Spectroradiometry; Moderate resolution imaging spectroradiometer; Space remote sensing; Carbon dioxide; data processing; Infrared absorption; Satellite observation; cartography; Ice cloud; Polar orbiting satellite; greenhouse gas; Water level; Effective radius; water vapor; Absorption band; Forecast skill; Precipitable water; theoretical studies; Aqua satellite
• ISSN: 1558-8424; 1558-8432
• DOI: 10.1175/2010JAMC2364.1

Data Collection 5 processing for the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the NASA Earth Observing System (EOS)TerraandAquaspacecraft includes an algorithm for detecting multilayered clouds in daytime. The main objective of this algorithm is to detect multilayered cloud scenes, specifically optically thin ice cloud overlying a lower-level water cloud, that present difficulties for retrieving cloud effective radius using single-layer plane-parallel cloud models. The algorithm uses the MODIS 0.94-μm water vapor band along with CO₂ bands to obtain two above-cloud precipitable water retrievals, the difference of which, in conjunction with additional tests, provides a map of where multilayered clouds might potentially exist. The presence of a multilayered cloud results in a large difference in retrievals of above-cloud properties between the CO₂ and the 0.94-μm methods. In this paper the MODIS multilayered cloud algorithm is described, results of using the algorithm over example scenes are shown, and global statistics for multilayered clouds as observed by MODIS are discussed. A theoretical study of the algorithm behavior for simulated multilayered clouds is also given. Results are compared to two other comparable passive imager methods. A set of standard cloudy atmospheric profiles developed during the course of this investigation is also presented. The results lead to the conclusion that the MODIS multilayer cloud detection algorithm has some skill in identifying multilayered clouds with different thermodynamic phases.