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Revisiting Short-Wave-Infrared (SWIR) Bands for Atmospheric Correction in Coastal WatersThe shortwave infrared (SWIR) bands on the existing Earth Observing missions like MODIS have been designed to meet land and atmospheric science requirements. The future geostationary and polar-orbiting ocean color missions, however, require highly sensitive SWIR bands (greater than 1550nm) to allow for a precise removal of aerosol contributions. This will allow for reasonable retrievals of the remote sensing reflectance (R(sub rs)) using standard NASA atmospheric corrections over turbid coastal waters. Design, fabrication, and maintaining high-performance SWIR bands at very low signal levels bear significant costs on dedicated ocean color missions. This study aims at providing a full analysis of the utility of alternative SWIR bands within the 1600nm atmospheric window if the bands within the 2200nm window were to be excluded due to engineering/cost constraints. Following a series of sensitivity analyses for various spectral band configurations as a function of water vapor amount, we chose spectral bands centered at 1565 and 1675nm as suitable alternative bands within the 1600nm window for a future geostationary imager. The sensitivity of this band combination to different aerosol conditions, calibration uncertainties, and extreme water turbidity were studied and compared with that of all band combinations available on existing polar-orbiting missions. The combination of the alternative channels was shown to be as sensitive to test aerosol models as existing near-infrared (NIR) band combinations (e.g., 748 and 869nm) over clear open ocean waters. It was further demonstrated that while in extremely turbid waters the 1565/1675 band pair yields R(sub rs) retrievals as good as those derived from all other existing SWIR band pairs (greater than 1550nm), their total calibration uncertainties must be less than 1% to meet current science requirements for ocean color retrievals (i.e., delta R(sub rs) (443) less than 5%). We further show that the aerosol removal using the NIR and SWIR bands (available on the existing polar-orbiting missions) can be very sensitive to calibration uncertainties. This requires the need for monitoring the calibration of these bands to ensure consistent multi-mission ocean color products in coastal/inland waters.
Document ID
20170004576
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Pahlevan, Nima (Science Systems and Applications, Inc. Greenbelt, MD, United States)
Roger, Jean-Claude (Maryland Univ. College Park, MD, United States)
Ahmad, Ziauddin (JHT, Inc. Orlando, FL, United States)
Date Acquired
May 15, 2017
Publication Date
March 7, 2017
Publication Information
Publication: Optics Express
Volume: 25
Issue: 6
Subject Category
Oceanography
Earth Resources and Remote Sensing
Report/Patent Number
GSFC-E-DAA-TN42381
Funding Number(s)
CONTRACT_GRANT: NNX14AR70A
CONTRACT_GRANT: NNG15HQ01C
CONTRACT_GRANT: NNG14HZ03C
Distribution Limits
Public
Copyright
Other
Keywords
atmospheric correction
remote sensing