AVIRIS Bathymetry: Comparison to Multi-Beam Depths off Sarasota, FL by Michelle McIntyre Kendall Carder David Naar College of Marine Science, UFS

AVIRIS (Lee method) vs. Multi-beam depths: RMS =

% Error vs. Distance Offshore: note region beyond 15 km

Rrs(550) versus Distance Offshore: note region beyond 15 km Dark Bright Problem Area

AVIRIS Albedo ranges from 0.12 to 26% except beyond 14 km

Approximate dive locations for  b measurements (Mazel)

Albedos at 550 nm < 0.3, C. Mazel macro algae sand hard bottom

RMS = for pixels with  a < 0.3

Y = x x – ; fit to 5x5 median- filtered data

RMS = for parabolic-corrected, filtered data with  b < 0.3

An AUV could provide denied-access bathymetry for parabolic corrections and to determine problem areas

Shows where data are most realistic Problem area

Conclusions AVIRIS hyper-spectral bathymetry was accurate to 13.5% off Sarasota in May 2000 Removal of noise by median filtering and albedo filtering reduced errors to 8.8% Parabolic correction with a few lines of AUV data could further reduce bathymetry errors to perhaps 7% Problem area beyond 14 km may be suspended sediment transported over an algal bottom, falsely shoaling AVIRIS depths and exaggerating bottom albedos Lee algorithm disallows vertical structure in optical properties AUV data could also be used to detect vertical structure Hyper-spectral bathymetry without validation (e.g. AUV) not advised for denied-access locations unless to flag shoals

PHILLS WFS Lines April 2001 Line 1 Line 2 Line 3 Vicarious calibration of PHILLS

Chl a field from PHILLS WFS April 2001 flight off Charlotte Harbor in ~50 m of water. R/V Link is seen in upper left of image. Note the “wash-board effect” of noise, probably due to the amplifier. Ship value of chlorophyll was 0.125, close to PHILLS values mg m -3. Noise effect is about ±0.002 mg m Vicarious calibration of PHILLS data reported last year for Line 1 was extended to other lines, which were then atmo- spherically corrected (Chen, Carder, and Steward in prep.) and evaluated using applications. 0.10

Inshore region of Line 2 with locations for the following Rrs spectra:

P2 P1 P3

Inshore region of Line 3 with locations for the following Rrs spectra:

P2 P1 P3