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TitleAerosol Optical Depth for Atmospheric Correction of AVHRR Composite Data
DownloadDownloads (Preprint)
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorFedosejevs, G; O'Neill, N; Royer, A; Teillet, P M; Bokoye, A I; McArthur, B
SourceCanadian Journal of Remote Sensing vol. 26, issue 4, 2000 p. 273-284,
Alt SeriesEarth Sciences Sector, Contribution Series 20042845
PublisherInforma UK Limited
Mediapaper; on-line; digital
File formatpdf
Subjectsremote sensing; GeoComp-n; AVHRR; NOAA; AEROCAN; Data processing
Illustrationstables; graphs
Released2014 07 31
AbstractThe Canada Centre for Remote Sensing (CCRS) Geocoding and Compositing system (GeoComp-n) processes the Advanced Very High Resolution Radiometer (AVHRR) data from the United States National Oceanic and Atmospheric Administration (NOAA) series of satellites. The GeoComp-n system produces single- or multi-date composite maps of surface reflectance of the Canada landmass in the AVHRR visible and near-infrared spectral bands at a spatial resolution of 1 km. The data must first be processed into accurate geophysical units in order to utilize these maps and their derived products for various global climate and land cover change studies. In the case of satellite data, this not only implies the accurate radiometric calibration but also the proper atmospheric correction of image data. One of the key parameters required for atmospheric correction is the aerosol optical depth. The Canadian sunphotometer network, AEROCAN, provides spatially sparse but near real-time (seasonal) aerosol optical depth coverage across Canada. One of the goals of AEROCAN is to develop an aerosol climatology that can be used for operational atmospheric correction of satellite data. This research note reviews the current holdings in the AEROCAN aerosol database after cloud screening. The data tables and seasonal profiles presented support the conclusion at this time that a single, Canada-wide, time-invariant optical depth is acceptable for the first order operational atmospheric correction of AVHRR composite image data. The best estimate of this aerosol optical depth at a wavelength of 500 nm (AOD500) is 0.07, with an uncertainty of +0.070/-0.035, as generated from the AEROCAN database. This corresponds to an aerosol optical depth at a wavelength of 550 nm (AOD550) of 0.062, with an uncertainty of +0.062/-0.031, for purposes of the atmospheric correction code in GeoComp-n. A sensitivity study demonstrates that this uncertainty in AOD500 produces an absolute error in surface reflectance of +1% for the worst case of a black spruce forest, which is acceptable for GeoComp-n with an accuracy requirement of +5%.

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