title: Novel optical techniques for detecting and classifying toxic dinoflagellate Karenia brevis blooms using satellite imagery.
abstract: Karenia brevis (K. brevis) blooms are of great interest and have been commonly reported throughout the Gulf of Mexico. In this study we propose a detection technique for blooms with low backscatter characteristics, which we name the Red Band Difference (RBD) technique, coupled with a selective K. brevis bloom classification technique, which we name the K. brevis Bloom Index (KBBI). These techniques take advantage of the relatively high solar induced chlorophyll fluorescence and low backscattering of K. brevis blooms. The techniques are applied to the detection and classification of K. brevis blooms from Moderate Resolution Imaging Spectroradiometer (MODIS) ocean color measurements off the Gulf of Mexico. To assess the efficacy of the techniques for detection and classification, simulations, including chlorophyll fluorescence (assuming 0.75% quantum yield) based on K. brevis blooms and non-K. brevis blooms conditions were performed. These show that effective bloom detection from satellite measurements requires a threshold of RBD>0.15W/m(2)/microm/sr, corresponding to about 5mg/m(3) of chlorophyll. Blooms can be detected at lower concentration by lowering the RBD threshold but false positives may increase. The classification technique is found most effective for thresholds of RBD>0.15W/m(2)/microm/sr and KBBI>0.3*RBD. The techniques were applied and shown to be effective for well documented blooms of K. brevis in the Gulf of Mexico and compared to other detection techniques, including FLH approaches. Impacts of different atmospheric corrections on results were also examined.
authors.affiliation: Optical Remote Sensing Laboratory, City College of City University of New York, 140th St @ Convent Ave, New York, NY 10031,USA.
authors.forename: Ruhul
authors.initials: R
authors.lastname: Amin
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.forename: Alex
authors.initials: A
authors.lastname: Gilerson
authors.forename: Barry
authors.initials: B
authors.lastname: Gross
authors.forename: Fred
authors.initials: F
authors.lastname: Moshary
authors.forename: Samir
authors.initials: S
authors.lastname: Ahmed
mesh_terms: D000818:Animals; D004141:Dinoflagellida / Q000737:chemistry / Q000145:classification* / Q000302:isolation & purification*; D004784:Environmental Monitoring; D009792:Oceans and Seas; D018531:Spacecraft; D013050:Spectrometry, Fluorescence / Q000295:instrumentation / Q000379:methods*; D014871:Water Microbiology