Abstract


REMOTE SPECTROSCOPIC RETRIEVAL OF APPARENT OPTICAL PROPERTIES AND BOTTOM REFLECTANCE IN SHALLOW CORAL ECOSYSTEMS

Remote spectroscopy in the 400-800 nm range can observe reflected light from shallow water benthic environments, simultaneously characterizing water properties and bottom composition. Specifically, airborne mapping spectrometers such as NASA's Portable Remote Imaging SpectroMeter (PRISM) are powerful tools to map coral reefs over wide areas. However, such inversions are difficult due to the intrinsic ambiguity in separating bottom reflectance, depth, and water optical properties, which leads to non-unique retrievals. While many retrieval algorithms have been developed, true operational spectroscopic mapping of coral reefs remains elusive. This work describes a method for accurate and stable bottom reflectance retrieval at speeds suitable for large remote sensing datasets, such as those of the forthcoming COral Reef Airborne Laboratory (CORAL) investigation. We capture water constituents using two apparent optical properties (AOPs): backscatter, and the “operational” attenuation term of Maritorena et al. (1994). These coefficients, along with depth, glint, and bottom reflectance, define a simple model for subsurface irradiance reflectance. Both AOPs and bottom reflectance use a nonnegative mixture representation, a subspace of variability based on a library of endmembers drawn from simulated or field data. We evaluate the approach by mapping Eelgrass and sediment in the Elkhorn Slough, and coral reef communities in the Florida Keys. The method provides stable results that are consistent with field validation, presaging its utility for mapping coral reefs over wide areas.

Authors

Thompson, D. R., Jet Propulsion Laboratory, California Institute of Technology, USA, David.R.Thompson@jpl.nasa.gov

Hochberg, E., Bermuda Institute of Ocean Sciences, Bermuda, Eric.Hochberg@bios.edu

Dierssen, H., University of Connecticut , USA, heidi.dierssen@uconn.edu

Garcia, R., University of Massachusetts Boston, USA, rodrigo.garcia@postgrad.curtin.edu.au

Gierach, M., Jet Propulsion Laboratory, California Institute of Technology, USA, Michelle.Gierach@jpl.nasa.gov

Lee, Z. P., University of Massachusetts Boston, USA, ZhongPing.Lee@umb.edu

Green, R., Jet Propulsion Laboratory, California Institute of Technology, USA, robert.o.green@jpl.nasa.gov

Maritorena, S., University of California Santa Barbara, USA, stephane@eri.ucsb.edu

Mouroulis, P., Jet Propulsion Laboratory, California Institute of Technology, USA, pantazis.mouroulis@jpl.nasa.gov

McCubbin, I., Jet Propulsion Laboratory, California Institute of Technology, USA, Ian.B.Mccubbin@jpl.nasa.gov

Details

Oral presentation

Session #:51
Date: 06/22/2016
Time: 15:30
Location: 312

Presentation is given by student: No