Cloud detection with MODIS. Part II: Validation

S. A. Ackerman; R. E. Holz; R. Frey; E. W. Eloranta; B. C. Maddux; M. McGill

doi:10.1175/2007JTECHA1053.1

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Cloud detection with MODIS. Part II: Validation

Journal article

Open access

Peer reviewed

Cloud detection with MODIS. Part II: Validation

S. A. Ackerman, R. E. Holz, R. Frey, E. W. Eloranta, B. C. Maddux and M. McGill

Journal of atmospheric and oceanic technology, Vol.25(7), pp.1073-1086

07/01/2008

DOI: 10.1175/2007JTECHA1053.1

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Abstract

An assessment of the performance of the Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask algorithm for Terra and Aqua satellites is presented. The MODIS cloud mask algorithm output is compared with lidar observations from ground [Arctic High-Spectral Resolution Lidar (AHSRL)], aircraft [Cloud Physics Lidar (CPL)], and satellite-borne [Geoscience Laser Altimeter System (GLAS)] platforms. The comparison with 3 yr of coincident observations of MODIS and combined radar and lidar cloud product from the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) site in Lamont, Oklahoma, indicates that the MODIS algorithm agrees with the lidar about 85% of the time. A comparison with the CPL and AHSRL indicates that the optical depth limitation of the MODIS cloud mask is approximately 0.4. While MODIS algorithm flags scenes with a cloud optical depth of 0.4 as cloudy, approximately 90% of the mislabeled scenes have optical depths less than 0.4. A comparison with the GLAS cloud dataset indicates that cloud detection in polar regions at night remains challenging with the passive infrared imager approach. In anticipation of comparisons with other satellite instruments, the sensitivity of the cloud mask algorithm to instrument characteristics (e. g., instantaneous field of view and viewing geometry) and thresholds is demonstrated. As expected, cloud amount generally increases with scan angle and instantaneous field of view (IFOV). Nadir sampling represents zonal monthly mean cloud amounts but can have large differences for regional studies when compared to full-swath-width analysis.

Engineering

Engineering, Ocean

Meteorology & Atmospheric Sciences

Physical Sciences

Science & Technology

Technology

Details

Title: Subtitle: Cloud detection with MODIS. Part II: Validation
Creators: S. A. Ackerman - Cooperative Institute for Meteorological Satellite Studies
R. E. Holz - Cooperative Institute for Meteorological Satellite Studies
R. Frey - Cooperative Institute for Meteorological Satellite Studies
E. W. Eloranta - University of Wisconsin–Madison
B. C. Maddux - University of Wisconsin–Madison
M. McGill - Goddard Space Flight Center
Resource Type: Journal article
Publication Details: Journal of atmospheric and oceanic technology, Vol.25(7), pp.1073-1086
DOI: 10.1175/2007JTECHA1053.1
ISSN: 0739-0572
eISSN: 1520-0426
Publisher: Amer Meteorological Soc
Number of pages: 14
Language: English
Date published: 07/01/2008
Academic Unit: Physics and Astronomy; Chemical and Biochemical Engineering
Record Identifier: 9984276452502771

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