Bottom Reflectance in Ocean Color Satellite Remote Sensing for Coral Reef Environments

Remote Sensing

Martina Reichstetter⁴  Peter R. C. S. Fearns⁵  Scarla J. Weeks⁴  Lachlan I. W. McKinna¹  Chris Roelfsema⁴  Miles Furnas²  Deepak R. Mishra³  Richard W. Gould³  Richard Gloaguen³ 

[1] NASA Goddard Space Flight Center, Code 616, Greenbelt, MD 20771, USA;Australian Institute of Marine Science, PMB 3, Townville, QLD 4810, Australia;;Biophysical Remote Sensing Research Centre, School of Geography, Planning and Environmental Management, University of Queensland, St Lucia, QLD 4072, AustraliaBiophysical Remote Sensing Research Centre, School of Geography, Planning and Environmental Management, University of Queensland, St Lucia, QLD 4072, Australia;Remote Sensing and Satellite Research Group, Department of Imaging and Applied Physics, Curtin University, Perth, WA 6845, Australia;

关键词: MODIS;    SeaWiFS;    optically shallow water;    radiative transfer modeling;    spectral separability;    cluster analysis;   

DOI  :  10.3390/rs71215852

来源: mdpi

【 摘 要 】

Most ocean color algorithms are designed for optically deep waters, where the seafloor has little or no effect on remote sensing reflectance. This can lead to inaccurate retrievals of inherent optical properties (IOPs) in optically shallow water environments. Here, we investigate in situ hyperspectral bottom reflectance signatures and their separability for coral reef waters, when observed at the spectral resolutions of MODIS and SeaWiFS sensors. We use radiative transfer modeling to calculate the effects of bottom reflectance on the remote sensing reflectance signal, and assess detectability and discrimination of common coral reef bottom classes by clustering modeled remote sensing reflectance signals. We assess 8280 scenarios, including four IOPs, 23 depths and 45 bottom classes at MODIS and SeaWiFS bands. Our results show: (i) no significant contamination (R_rscorr < 0.0005) of bottom reflectance on the spectrally-averaged remote sensing reflectance signal at depths >17 m for MODIS and >19 m for SeaWiFS for the brightest spectral reflectance substrate (light sand) in clear reef waters; and (ii) bottom cover classes can be combined into two distinct groups, “light” and “dark”, based on the modeled surface reflectance signals. This study establishes that it is possible to efficiently improve parameterization of bottom reflectance and water-column IOP retrievals in shallow water ocean color models for coral reef environments.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.