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Browsing by Author "Bernard, Stewart"

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An algorithm for detecting trophic status (chlorophyll-a), cyanobacterial-dominance, surface scums and floating vegetation in inland and coastal waters

Author: Matthews, MW ; Bernard, Stewart ; Robertson, L Date: Sep 2012 A novel algorithm is presented for detecting trophic status (chlorophyll-a), cyanobacterial blooms (cyano-blooms), surface scum and floating vegetation in coastal and inland waters using top-ofatmosphere data from the Medium Resolution Imaging ... Read more
Application of Sentinel 3 OLCI for chl-a retrieval over small inland water targets: Successes and challenges

Author: Kravitz, J ; Matthews, M ; Bernard, Stewart ; Griffith, Derek J Date: Feb 2020 Eutrophication and increasing prevalence of potentially toxic cyanobacterial blooms among global inland water bodies is becoming a major concern and requires direct attention. The European Space Agency recently launched the Ocean and Land ... Read more
The assessment of optimal MERIS ocean colour products in the shelf waters of the KwaZulu-Natal Bight, South Africa

Author: Smith, Marie E ; Bernard, Stewart ; O'Donoghue, S Date: Oct 2013 The KwaZulu-Natal Bight is a highly variable bio-optical environment, where waters over the shelf can change from the oligotrophic case 1 conditions of the Agulhas Current to the case 2 inshore environment influenced by upwelling and riverine ... Read more
Bio-optical profiling floats as new observational tools for biogeochemical and ecosystem studies: Potential synergies with ocean color remote sensing

Author: Claustre, H ; Bishop, J ; Boss, E ; Bernard, Stewart ; Berthon, J-F ; Coatanoan, C ; Johnson, K ; Lotiker, A ; Ulloa, O ; Perry, MJ ; D'Ortenzio, F ; Hembise Fanton D'andon, O ; Uitz, J Date: Sep 2009 Profiling floats now represent a mature technology. In parallel with their emergence, the field of miniature, low power bio-optical and biogeochemical sensors is rapidly evolving. Over recent years, the bio-geochemical and bio-optical community ... Read more
Bio-Optical sensors on Argo Floats. Reports of the international ocean-colour coordinating group

Author: Bernard, Stewart ; Berthon, J-F ; Bishop, J ; Boss, E ; Claustre, H ; Coatanoan, C ; D'Ortenzio, F ; Johnson, K ; Lotliker, A ; Ulloa, O Date: 2011 The International Ocean-Colour Coordinating Group (IOCCG) is an international group of experts in the field of satellite ocean colour, acting as a liaison and communication channel between users, managers and agencies in the ocean-colour ... Read more
Biophysical modelling of phytoplankton communities from first principles using two-layered spheres: Equivalent Algal Populations (EAP) model

Author: Robertson Lain, L ; Bernard, Stewart ; Evers-King, H Date: Jul 2014 There is a pressing need for improved bio-optical models of high biomass waters as eutrophication of coastal and inland waters becomes an increasing problem. Seasonal boom conditions in the Southern Benguela and persistent harmful algal ... Read more
Calibration of an in-water multi-excitation fluorometer for the measurement of phytoplankton chlorophyll-a fluorescence quantum yield

Author: Griffith, Derek J ; Bone, Emma L ; Thomalla, Sandy J ; Bernard, Stewart Date: Jul 2018 A multi-excitation fluorometer (MFL, JFE Advantech Co., Ltd.), originally designed to discriminate between phytoplankton species present within a population, has been redirected for use in fluorescence quantum yield (FQY) determination. While ... Read more
Characterizing the absorption properties for remote sensing of three small optically-diverse South African reservoirs

Author: Matthews, MW ; Bernard, Stewart Date: Sep 2013 Characterizing the specific inherent optical properties (SIOPs) of water constituents is fundamental to remote sensing applications. Therefore, this paper presents the absorption properties of phytoplankton, gelbstoff and tripton for three ... Read more
Developing global capabilities for the observation and predication of harmful algal blooms

Author: Bernard, Stewart ; Kudela, R ; Velo-Suarez, L Date: 2014 The majority of coastal regions and many freshwater systems across the globe are negatively affected by Harmful Algal Blooms (HABs). The impact of such blooms has grown in recent decades, with regard to public health, ecosystem function, ... Read more
Distinguishing cyanobacteria from algae in optically complex inland waters using a hyperspectral radiative transfer inversion algorithm

Author: Matthews, MW ; Bernard, Stewart ; Evers-King, H ; Robertson Lain, L Date: Oct 2020 A hyperspectral inversion algorithm was used to distinguish between cyanobacteria and algal blooms in optically complex inland waters. A framework for the algorithm is presented that incorporates a bio-optical model, a solution for the radiative ... Read more
Dynamics of oxygen depletion in the nearshore of a coastal embayment of the southern Benguela upwelling system

Author: Pitcher, GC ; Probyn, TA ; Du Randt, A ; Lucas, AJ ; Bernard, Stewart ; Evers-King, H ; Lamont, T ; Hutchings, L Date: Apr 2014 Acquisition of high resolution time series of water column and bottom dissolved oxygen (DO) concentrations inform the dynamics of oxygen depletion in St Helena Bay in the southern Benguela upwelling system at several scales of variability. ... Read more
Eutrophication and cyanobacteria in South Africa’s standing water bodies: A view from space

Author: Matthews, MW ; Bernard, Stewart Date: May 2015 Satellite remote sensing can make a significant contribution to monitoring water quality in South African standing water bodies. Eutrophication, defined as enrichment by nutrients, and toxin-producing cyanobacteria (blue-green algae) blooms ... Read more
Evaluation of chlorophyll-a and POC MODIS aqua products in the Southern Ocean

Author: Moutier, William ; Thomalla, Sandy J ; Bernard, Stewart ; Wind, G ; Ryan-Keogh, Thomas J ; Smith, Marie E Date: Jul 2019 The Southern Ocean (SO) is highly sensitive to climate change. Therefore, an accurate estimate of phytoplankton biomass is key to being able to predict the climate trajectory of the 21st century. In this study, MODerate resolution Imaging ... Read more
Harmful algal blooms and climate change: Learning from the past and present to forecast the future

Author: Wells, ML ; Trainer, VL ; Smayda, TJ ; Karlson, BSO ; Trick, CG ; Kudela, RM ; Ishikawa, A ; Bernard, Stewart ; Wulff, A ; Anderson, DM ; Cochlan, WP Date: Nov 2015 Climate change pressures will influence marine planktonic systems globally, and it is conceivable that harmful algal blooms may increase in frequency and severity. These pressures will be manifest as alterations in temperature, stratification, ... Read more
Ocean colour remote sensing of harmful algal blooms in the Benguela system

Author: Bernard, Stewart ; Pitcher, G ; Evers-King, H ; Robertson, L ; Matthews, M ; Rabagliati, A ; Balt, C Date: 2014 The Benguela, as a highly productive upwelling system, suffers from the occurrence of a variety of harmful algal blooms, most of which are associated with elevated biomass; a feature common to the shelf environment of upwelling systems. Most ... Read more
An optimized Chlorophyll a switching algorithm for MERIS and OLCI in phytoplankton-dominated waters

Author: Smith, Marie E ; Robertson, lain L ; Bernard, Stewart Date: Jun 2018 Productive upwelling zones such as the southern Benguela can exhibit phytoplankton biomass variability over several orders of magnitude, from near oligotrophic offshore waters to hypertrophic inshore blooms of>100 mgm (sup-3). This introduces ... Read more
Potential for high fidelity global mapping of common inland water quality products at high spatial and temporal resolutions based on a synthetic data and machine learning approach

Author: Kravitz, J ; Matthews, M ; Lain, L ; Fawcett, S ; Bernard, Stewart Date: Mar 2021 There is currently a scarcity of paired in-situ aquatic optical and biogeophysical data for productive inland waters, which critically hinders our capacity to develop and validate robust retrieval models for Earth Observation applications. ... Read more
Remote sensing of cyanobacteria-dominant algal blooms and water quality parameters in Zeekoevlei, a small hypertrophic lake, using MERIS

Author: Matthews, MW ; Bernard, Stewart ; Winter, K Date: Sep 2010 Eutrophication and cyanobacterial algal blooms present an increasing threat to the health of freshwater ecosystems and to humans who use these resources for drinking and recreation. Remote sensing is being used increasingly as a tool for ... Read more
Remote sensing of euphotic depth in shallow tropical inland waters of Lake Naivasha using MERIS data

Author: Majozi, Nobuhle P ; Suhyb Salama, MHD ; Bernard, Stewart ; Harper, DM ; Habte, MG Date: May 2014 Freshwater resources are deteriorating rapidly due to human activities and climate change. Remote sensing techniques have shown potential for monitoring water quality in shallow inland lakes, especially in data-scarce areas. The purpose of ... Read more
Requirements for forecasting harmful algal blooms in the Benguela

Author: Bernard, Stewart ; Kudela, RM ; Franks, P ; Fennel, W ; Kemp, A ; Fawcett, A ; Pitcher, GC Date: 2006 The Benguela system suffers from the frequent occurence of a variety of harmful algal blooms (HABs).These blooms can have severe negative impacts on local marine ecosystems and communities, in addition to commercial marine concerns such as ... Read more

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