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SWIM: A Semi-Analytical Ocean Color Inversion Algorithm for Optically Shallow WatersIn clear shallow waters, light that is transmitted downward through the water column can reflect off the sea floor and thereby influence the water-leaving radiance signal. This effect can confound contemporary ocean color algorithms designed for deep waters where the seafloor has little or no effect on the water-leaving radiance. Thus, inappropriate use of deep water ocean color algorithms in optically shallow regions can lead to inaccurate retrievals of inherent optical properties (IOPs) and therefore have a detrimental impact on IOP-based estimates of marine parameters, including chlorophyll-a and the diffuse attenuation coefficient. In order to improve IOP retrievals in optically shallow regions, a semi-analytical inversion algorithm, the Shallow Water Inversion Model (SWIM), has been developed. Unlike established ocean color algorithms, SWIM considers both the water column depth and the benthic albedo. A radiative transfer study was conducted that demonstrated how SWIM and two contemporary ocean color algorithms, the Generalized Inherent Optical Properties algorithm (GIOP) and Quasi-Analytical Algorithm (QAA), performed in optically deep and shallow scenarios. The results showed that SWIM performed well, whilst both GIOP and QAA showed distinct positive bias in IOP retrievals in optically shallow waters. The SWIM algorithm was also applied to a test region: the Great Barrier Reef, Australia. Using a single test scene and time series data collected by NASA's MODIS-Aqua sensor (2002-2013), a comparison of IOPs retrieved by SWIM, GIOP and QAA was conducted.
Document ID
20180002856
Acquisition Source
Goddard Space Flight Center
Document Type
Presentation
Authors
McKinna, Lachlan I. W.
(Curtin Univ. of Technology Perth, Australia)
Werdell, P. Jeremy
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Fearns, Peter R. C. S.
(Curtin Univ. of Technology Perth, Australia)
Weeks, Scarla J.
(Queensland Univ. Australia)
Reichstetter, Martina
(Queensland Univ. Australia)
Franz, Bryan A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Bailey, Sean W.
(FutureTech Corp. Greenbelt, MD, United States)
Shea, Donald M.
(Science Applications International Corp. Greenbelt, MD, United States)
Feldman, Gene C.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
May 16, 2018
Publication Date
October 26, 2014
Subject Category
Oceanography
Report/Patent Number
GSFC-E-DAA-TN18960
Meeting Information
Meeting: Ocean Optics Conference
Location: Portland, ME
Country: United States
Start Date: October 26, 2014
End Date: October 31, 2014
Sponsors: NASA Headquarters
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
shallow waters
swim
ocean color
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