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Validation of MODIS cloud mask and multilayer flag using CloudSat‐CALIPSO cloud profiles and a cross‐reference of their cloud classifications
Author(s) -
Wang Tao,
Fetzer Eric J.,
Wong Sun,
Kahn Brian H.,
Yue Qing
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2016jd025239
Subject(s) - lidar , moderate resolution imaging spectroradiometer , cloud top , environmental science , cirrus , cloud fraction , cloud height , cloud computing , remote sensing , aerosol , atmospheric sciences , cloud cover , meteorology , cloud albedo , satellite , geology , geography , physics , computer science , astronomy , operating system
Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6 cloud observations (MYD06) at 1 km are collocated with daytime CloudSat‐Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) (C‐C) cloud vertical structures (2B‐CLDCLASS‐LIDAR). For 2007–2010, over 267 million C‐C cloud profiles are used to (1) validate MODIS cloud mask and cloud multilayer flag and (2) cross‐reference between C‐C cloud types and MODIS cloud regimes defined by joint histograms of cloud top pressure (CTP) and cloud optical depth ( τ ). Globally, of total observations, C‐C reports 27.1% clear and 72.9% cloudy, whereas MODIS reports 30.0% confidently clear and 58.7% confidently cloudy, with the rest 7.1% as probably clear and 4.2% as probably cloudy. Agreement between MODIS and C‐C is 77.8%, with 20.9% showing both clear and 56.9% showing both cloudy. The 9.1% of observations are clear in MODIS but cloudy in C‐C, indicating clouds missed by MODIS; 1.8% of observations are cloudy in MODIS but clear in C‐C, likely due to aerosol/dust or surface snow layers misidentified by MODIS. C‐C reports 47.4/25.5% single‐layer/multilayer clouds, while MODIS reports 26.7/14.0%. For C‐C single‐layer clouds, ~90% of tropical MODIS high (CTP < 440 hPa) and optically thin ( τ < 3.6) clouds are identified as cirrus and ~60% of high and optically thick ( τ > 23) clouds are recognized as deep convective in C‐C. Approximately 70% of MODIS low‐level (CTP > 680 hPa) clouds are classified as stratocumulus in C‐C regardless of region and optical thickness. No systematic relationship exists between MODIS middle‐level (680 < CTP < 440 hPa) clouds and C‐C cloud types, largely due to different definitions adopted.