HYPERSPECTRAL REMOTE SENSING OF BENTHIC MARINE COMMUNITIES IN LA PARGUERA, PUERTO RICO

1
HYPERSPECTRAL REMOTE SENSING OF BENTHIC MARINE
COMMUNITIES IN LA PARGUERA, PUERTO RICO
R.A. Armstrong and F. Gilbes1
Bio-Optical Oceanography Laboratory NOAA
Center for Atmospheric Sciences 1Geology
Department University of Puerto Rico at
Mayagüez
2
Research Objectives

• To use AVIRIS hyperspectral data for coral reef
  benthic mapping and change detection.
• Combine AVIRIS data with field measurements to
  assess the ecological impact of the 2005 coral
  bleaching event in Southwestern Puerto Rico.

3
AVIRIS 2005 Mission
Airborne Visible-Infrared Imaging Spectrometer
(AVIRIS) 224 spectral bands

• Puerto Rico Flighlines
• December 12-13, 2005
• Altitude 3.5 km
• Pixel Size 3.1 m

• 224 Spectral Bands, 400-2500 nm
• Spectral Resolution 10 nm
• Twin Otter Aircraft

Flight lines for La Parguera, Southwestern
PR 26 Flighlines Solar azimuth lines
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
AVIRIS Data Processing
8
AVIRIS Stray-Light Anomaly of 2004-2005 Data
Uncorrected
Halo Suppression
9
Spectral Library of Coral Reef Benthic Components
Spectral Reflectance Data using GER-1500
Spectroradiometer
10
Coral Reef Benthic Components
11
Atmospherically-Corrected AVIRIS Image
12
Water Column Corrections
1. Empirical Line Method
Relies on field measurements of homogeneous area
or flat fields DN(b) ?(b)A(b) B(b) ?
reflectance of surface material A
multiplicative term, B additive term
13
Underwater Flat-Field Calibration Targets for
Water Column Correction
14
AVIRIS Benthic Spectra After Water Column
Correction
Coral
Sand
Seagrass
15
Water Column Correction Validation

• AVIRIS agrees with field values within 10 from
  400-600 nm and
• up to 18 between 600-700 nm.
• Spectral features are preserved, mostly
  corresponding to pigment
• absorption by microbial layers.
• However, the water column correction is only
  good for a depth of 2 m.

16
Water Column Corrections
2. Benthic Reflectance Model
17
Spectral Kd for December 12, 2005
18
LIDAR Bathymetry of Southwestern Puerto Rico
19
(No Transcript)
20
Acknowledgements
Dr. Liane Guild and Brad Lobitz (NASA) Dr.
Yasmín Detrés, Sara Rivero, Carmen Zayas
(UPRM) Sponsored by NASA Ocean Biogeochemistry
Program Center for Subsurface Sensing and Imaging
(CenSSIS) NSF