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Journal of Applied Remote Sensing • Open Access

Satellite retrievals of Karenia brevis harmful algal blooms in the West Florida shelf using neural networks and impacts of temporal variabilities
Author(s): Ahmed El-Habashi; Claudia M. Duran; Vincent Lovko; Michelle C. Tomlinson; Richard P. Stumpf; Sam Ahmed

Paper Abstract

We apply a neural network (NN) technique to detect/track Karenia brevis harmful algal blooms (KB HABs) plaguing West Florida shelf (WFS) coasts from Visible-Infrared Imaging Radiometer Suite (VIIRS) satellite observations. Previously KB HABs detection primarily relied on the Moderate Resolution Imaging Spectroradiometer Aqua (MODIS-A) satellite, depending on its remote sensing reflectance signal at the 678-nm chlorophyll fluorescence band (Rrs678) needed for normalized fluorescence height and related red band difference retrieval algorithms. VIIRS, MODIS-A’s successor, does not have a 678-nm channel. Instead, our NN uses Rrs at 486-, 551-, and 671-nm VIIRS channels to retrieve phytoplankton absorption at 443 nm ( a ph 443 ). The retrieved a ph 443 images are next filtered by applying limits, defined by (i) low Rrs551-nm backscatter and (ii) a minimum a ph 443 value associated with KB HABs. The filtered residual images are then converted to show chlorophyll-a concentrations [Chla] and KB cell counts. VIIRS retrievals using our NN and five other retrieval algorithms were compared and evaluated against numerous in situ measurements made over the four-year 2012 to 2016 period, for which VIIRS data are available. These comparisons confirm the viability and higher retrieval accuracies of the NN technique, when combined with the filtering constraints, for effective detection of KB HABs. Analysis of these results as well as sequential satellite observations and recent field measurements underline the importance of short-term temporal variabilities on retrieval accuracies.

Paper Details

Date Published: 11 May 2017
PDF: 23 pages
J. Appl. Rem. Sens. 11(3) 032408 doi: 10.1117/1.JRS.11.032408
Published in: Journal of Applied Remote Sensing Volume 11, Issue 3
Show Author Affiliations
Ahmed El-Habashi, The City College of New York (United States)
Claudia M. Duran, The City College of New York (United States)
Vincent Lovko, Mote Marine Laboratories (United States)
Michelle C. Tomlinson, National Oceanic and Atmospheric Administration, National Centers for Coastal Ocean Science (United States)
Richard P. Stumpf, National Oceanic and Atmospheric Administration, National Centers for Coastal Ocean Science (United States)
Sam Ahmed, The City College of New York (United States)


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