NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Clues to Coral Reef Health: Integrating Radiative Transfer Modeling and Hyperspectral DataAn important contribution to coral reef research is to improve spectral distinction between various health states of coral species in areas subject to harmful anthropogenic activity and climate change. New insights into radiative transfer properties of corals under healthy and stressed conditions can advance understandings of ecological processes on reefs and allow better assessments of the impacts of large-scale bleaching and disease events, Our objective was to examine the spectral and spatial properties of hyperspectral sensors that may be used to remotely sense changes in reef community health. We compare in situ reef environment spectra (healthy coral, stressed coral, dead coral, algae, and sand) with airborne hyperspectral data to identify important spectral characteristics and indices. Additionally, spectral measurements over a range of water depths, relief, and bottom types are compared to help quantify bottom-water column influences. In situ spectra were collected in July and August 2002 at the Long Rock site in the Andros Island, Bahamas coastal zone coral reef. Our primary emphasis was on Acropora palmata (or elkhorn coral), a major reef building coral, which is prevalent in the study area, but is suffering from white band disease. A. palmata is currently being, proposed as an endangered species because its populations have severely declined in many areas of the Caribbean. In addition to the A. palmata biotope, we have collected spectra of at least seven other coral biotopes that exist within the study area, each with different coral community composition, density of corals, relief, and size of corals. Coral spectral reflectance was then input into a radiative transfer model, CORALMOD (CM1), which is based on a leaf radiative transfer model. In CM1, input coral reflectance measurements produce modeled reflectance through an inversion at each visible wavelength to provide the absorption spectrum. Initially, we imposed a scattering baseline that is the same regardless of the coral condition and that coral is optically thick and no light is transmitted through coral. Here we will focus on methodology, experimental design, and initial findings of the in situ spectral measurements and preliminary output from the radiative transfer model.
Document ID
20030002392
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Guild, Liane
(NASA Ames Research Center Moffett Field, CA United States)
Ganapol, Barry
(Arizona Univ. Tucson, AZ United States)
Kramer, Philip
(Miami Univ. FL United States)
Armstrong, Roy
(Puerto Rico Univ. Lajas, Puerto Rico)
Gleason, Art
(Miami Univ. FL United States)
Torres, Juan
(Puerto Rico Univ. Lajas, Puerto Rico)
Johnson, Lee
(NASA Ames Research Center Moffett Field, CA United States)
Garfield, Toby
(San Francisco State Univ. CA United States)
Peterson, David L.
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Subject Category
Oceanography
Meeting Information
Meeting: American Geophysical Union Fall Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 6, 2002
End Date: December 10, 2002
Sponsors: American Geophysical Union
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Available Downloads

There are no available downloads for this record.
No Preview Available