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Remote Sens. 2013, 5(9), 4370-4404; doi:10.3390/rs5094370
Article

Characterizing the Absorption Properties for Remote Sensing of Three Small Optically-Diverse South African Reservoirs

1,*  and 1,2
Received: 16 July 2013; in revised form: 30 August 2013 / Accepted: 3 September 2013 / Published: 9 September 2013
(This article belongs to the Special Issue Remote Sensing of Phytoplankton)
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Abstract: Characterizing the specific inherent optical properties (SIOPs) of water constituents is fundamental to remote sensing applications. Therefore, this paper presents the absorption properties of phytoplankton, gelbstoff and tripton for three small, optically-diverse South African inland waters. The three reservoirs,  Hartbeespoort, Loskop and Theewaterskloof, are challenging for remote sensing, due to differences in phytoplankton assemblage and the considerable range of constituent concentrations. Relationships between the absorption properties and biogeophysical parameters, chlorophyll-a (chl-a), TChl (chl-a plus  phaeopigments),  seston,  minerals  and  tripton, are established. The value determined for the mass-specific tripton absorption coefficient at 442 nm, a(442), ranges from 0.024 to 0.263 m2·g1. The value of the TChl-specific phytoplankton absorption coefficient (a ) was strongly influenced by phytoplankton species, size, accessory pigmentation and biomass. a(440) ranged from 0.056 to 0.018 m2·mg1 in oligotrophic to hypertrophic waters. The positive relationship between cell size and trophic state observed in open ocean waters was violated by significant small cyanobacterial populations. The phycocyanin-specific phytoplankton  absorption  at  620  nm,  a(620), was determined as 0.007 m2·g1 in a M. aeruginosa bloom. Chl-a was a better indicator of phytoplankton biomass than phycocyanin (PC) in surface scums, due to reduced accessory pigment production. Absorption budgets demonstrate that monospecific blooms of M. aeruginosa and C. hirundinella may be treated as “cultures”, removing some complexities for remote sensing applications.   These results contribute toward a better understanding of IOPs and remote sensing applications in hypertrophic inland waters. However, the majority of the water is optically complex, requiring the usage of all the SIOPs derived here for remote sensing applications. The SIOPs may be used for developing remote sensing algorithms for the detection of biogeophysical  parameters,  including chl-a, suspended matter, tripton and gelbstoff, and in advanced remote sensing studies for phytoplankton type detection.
Keywords: remote sensing; inherent optical properties; inland waters; absorption; phycocyanin; tripton; phytoplankton; South Africa remote sensing; inherent optical properties; inland waters; absorption; phycocyanin; tripton; phytoplankton; South Africa
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Matthews, M.W.; Bernard, S. Characterizing the Absorption Properties for Remote Sensing of Three Small Optically-Diverse South African Reservoirs. Remote Sens. 2013, 5, 4370-4404.

AMA Style

Matthews MW, Bernard S. Characterizing the Absorption Properties for Remote Sensing of Three Small Optically-Diverse South African Reservoirs. Remote Sensing. 2013; 5(9):4370-4404.

Chicago/Turabian Style

Matthews, Mark W.; Bernard, Stewart. 2013. "Characterizing the Absorption Properties for Remote Sensing of Three Small Optically-Diverse South African Reservoirs." Remote Sens. 5, no. 9: 4370-4404.


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