Deriving Inherent Optical Properties from Water Color: a Multiband Quasi-Analytical Algorithm for Optically Deep Waters

College of Marine Science, University of South Florida, St. Petersburg 33701, USA.
Applied Optics (Impact Factor: 1.78). 10/2002; 41(27):5755-72. DOI: 10.1364/AO.41.005755
Source: PubMed


For open ocean and coastal waters, a multiband quasi-analytical algorithm is developed to retrieve absorption and backscattering coefficients, as well as absorption coefficients of phytoplankton pigments and gelbstoff. This algorithm is based on remote-sensing reflectance models derived from the radiative transfer equation, and values of total absorption and backscattering coefficients are analytically calculated from values of remote-sensing reflectance. In the calculation of total absorption coefficient, no spectral models for pigment and gelbstoff absorption coefficients are used. Actually those absorption coefficients are spectrally decomposed from the derived total absorption coefficient in a separate calculation. The algorithm is easy to understand and simple to implement. It can be applied to data from past and current satellite sensors, as well as to data from hyperspectral sensors. There are only limited empirical relationships involved in the algorithm, and they are for less important properties, which implies that the concept and details of the algorithm could be applied to many data for oceanic observations. The algorithm is applied to simulated data and field data, both non-case1, to test its performance, and the results are quite promising. More independent tests with field-measured data are desired to validate and improve this algorithm.

Download full-text


Available from: Zhongping Lee
  • Source
    • "The constants result in a change of units from the unitless u to a per unit of solid angle, sr À1 , quantity r rs,l . The above-surface remote-sensing reflectance is given by (Lee et al., 2002): R rs;l ¼ 0:52r rs;l 1 À 1:7r rs;l (16) 2.1.4. Benthic reflectance of macrophytes, benthic microalgae and sediment types In order to calculate the importance of benthic reflectance, the integrated weighting of the water column must be calculated (Sec. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Aquatic biogeochemical models are vital tools in understanding and predicting human impacts on water clarity. In this paper, we develop a spectrally-resolved optical model that produces remote-sensing reflectance as a function of depth-resolved biogeochemical model properties such as phytoplankton biomass, suspended sediment concentrations and benthic reflectance. We compare simulated remote-sensing reflectance from a 4 km resolution coupled hydrodynamic, optical, sediment and biogeochemical model configured for the Great Barrier Reef with observed remote-sensing reflectance from the MODIS sensor at the 8 ocean colour bands. The optical model is sufficiently accurate to capture the remote-sensing reflectance that would arise from a specific biogeochemical state. Thus the mismatch between simulated and observed remote-sensing reflectance provides an excellent metric for model assessment of the coupled biogeochemical model. Finally, we combine simulated remote-sensing reflectance in a red/green/blue colour model to produce simulated true colour images during the passage of Tropical Cyclone Yasi in February 2011.
    Full-text · Article · Apr 2016 · Environmental Modelling and Software
  • Source
    • "The second group of algorithms comprise those are strongly driven by an understanding of the relationships between inherent optical properties (IOPs) (i.e., absorption, scattering and fluorescence) and the water-leaving radiative signal through the use of physics-based biooptical models. Several inversion techniques (e.g., spectral optimization, linear and non-linear matrix inversion) have been developed for retrieve IOPs and to relate these to in-water biogeochemical properties (Hoge and Lyon, 1996;Garver and Siegel, 1997;Lee et al., 1999Lee et al., , 2002Carder et al., 1999;Maritorena et al., 2002;Heege and Fischer, 2004;Smyth et al., 2006;Santini et al., 2010;Giardino et al., 2012;Werdell et al., 2013). Although, these models are physic-based many rely on empirical assumptions, while others require knowledge of the specific IOPs (SIOPs; i.e., absorption or scattering per unit mass) (Brando and Dekker, 2003). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The Earth's surface waters are a fundamental resource and encompass a broad range of ecosystems that are core to global biogeochemical cycling and food and energy production. Despite this, the Earth's surface waters are impacted by multiple natural and anthropogenic pressures and drivers of environmental change. The complex interaction between physical, chemical and biological processes in surface waters poses significant challenges for in situ monitoring and assessment and often limits our ability to adequately capture the dynamics of aquatic systems and our understanding of their status, functioning and response to pressures. Here we explore the opportunities that Earth observation (EO) has to offer to basin-scale monitoring of water quality over the surface water continuum comprising inland, transition and coastal water bodies, with a particular focus on the Danube and Black Sea region. This review summarises the technological advances in EO and the opportunities that the next generation satellites offer for water quality monitoring. We provide an overview of algorithms for the retrieval of water quality parameters and demonstrate how such models have been used for the assessment and monitoring of inland, transitional, coastal and shelf–sea systems. Further, we argue that very few studies have investigated the connectivity between these systems especially in large river–sea systems such as the Danube–Black Sea. Subsequently, we describe current capability in operational processing of archive and near real-time satellite data. We conclude that while the operational use of satellites for the assessment and monitoring of surface waters is still developing for inland and coastal waters and more work is required on the development and validation of remote sensing algorithms for these optically complex waters, the potential that these data streams offer for developing an improved, potentially paradigm-shifting understanding of physical and biogeochemical processes across large scale river–sea systems including the Danube–Black Sea is considerable.
    Full-text · Article · Jan 2016 · Science of The Total Environment
  • Source
    • "Thus, the achievability of accurate DOLP measurements from above-water instrumentation is demonstrated. RT computations are required to confirm Timofeyeva's observations; in particular, if the coefficients p and q are, indeed, only dependent on the viewing geometry, tabulated values of those coefficients could be used to retrieve the attenuation coefficient of the water body using data obtained with above-water polarization sensors (the absorption coefficient is routinely estimated from the remote sensing reflectance using well-established algorithms (Lee et al., 2002)). Extensive RT calculations are required to assess the dependence of the fitting coefficients on the specific geometrical configuration and "
    [Show abstract] [Hide abstract]
    ABSTRACT: Radiometric measurements by satellite sensors of the light field backscattered from the atmosphere-ocean system represent a powerful tool to monitor marine ecosystems, carbon cycle or water quality on the global scale. Estimations from space of the chlorophyll-a concentration and the subsequent estimate of the marine primary production, for instance, are currently being based on multi-spectral measurements of the water-leaving radiance regardless of its state of polarization. On the other hand, new investigations have been focused on the exploitation of polarization of light in the water column and exiting the sea surface to improve our capacities of observing and monitoring coastal and oceanic environments. This chapter attempts to give a brief overview of the recent developments on the use of polarization for marine environment monitoring including assessment of aerosol and atmospheric correction, sea state and associated winds, oceanic and coastal water content and, potentially, estimation of the ocean carbon stock. First, a short historical review of the successive discoveries punctuated our understanding of light polarization in the marine environment is given. After a description of the transfer of light in the atmosphere-ocean system, impacts of the water constituents (i.e., suspended particles, absorbing material) on polarization are summarized. Recent illustrations of the use and exploitation of light polarization for studying marine environment from laboratory to satellite applications are given. Through the chapter, benefits of polarimetric measurements for monitoring ocean, coastal or lake environments are discussed in view of the future launch of polarimetric Earth-observing satellite missions.
    Full-text · Chapter · Jan 2016
Show more