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Article Reference Detection and correction of adjacency effects in hyperspectral airborne data of coastal and inland waters: the use of the near infrared similarity spectrum
A method for the detection and correction of water pixels affected by adjacency effects is presented. The approach is based on the comparison of spectra with the near infrared (NIR) similarity spectrum. Pixels affected by adjacency effects have a water-leaving reflectance spectrum with a different shape to the reference spectrum. This deviation from the similarity spectrum is used as a measure for the adjacency effect. Secondly, the correspondence with the NIR similarity spectrum is used to quantify and to correct for the contribution of the background radiance during atmospheric correction. The advantage of the approach is that it requires no a priori assumptions on the sediment load or related reflectance values in the NIR and can therefore be applied to turbid waters. The approach is tested on hyperspectral airborne data (Compact Airborne Spectrographic Imager (CASI), Airborne Hyperspectral Scanner (AHS)) acquired above coastal and inland waters at different flight altitudes and under varying atmospheric conditions. As the NIR similarity spectrum forms the basis of the approach, the method will fail for water bodies for which this similarity spectrum is no longer valid.
Located in Library / RBINS Staff Publications
Article Reference Detection limits of tidal-wetland sequences to identify variable rupture modes of megathrust earthquakes
Located in Library / RBINS Staff Publications 2016
Article Reference Detection of Algal Blooms in European waters based on satellite chlorophyll data from MERIS and MODIS.
A technique for algal-bloom detection in European waters is described, based on standard chlorophyll a concentration (Chl) data from two ocean-colour sensors, the Moderate Resolution Imaging Spectroradiometer (MODIS) and Medium Resolution Imaging Spectrometer (MERIS). Comparison of the two data sources shows good agreement in case 1 waters, whereas the difference is significant in coastal waters including turbid areas. A relationship between the water-leaving reflectance at 667 nm and Chl for case 1 waters was used to eliminate pixels where Chl retrieval is contaminated by backscatter from inorganic suspended matter. Daily Chl data are compared to a predefined threshold map to determine whether an algal bloom has occurred. In this study, a threshold map was defined as the 90th percentile of previous years' data to take account of regional differences in typical Chl levels, with separate maps for each sensor to take account of sensor-specific bias. The algal-bloom detection processing chain is described, and example results are presented.
Located in Library / RBINS Staff Publications
Article Reference Detection of Bonobos (Pan Paniscus) in Tropical Rainforest Canopies Using Drone-Based Thermal Imaging: A First Step Towards Accurately Estimating Population Sizes?
Surveying great ape populations is time-consuming and costly, and often relies on generalised parameters, resulting in imprecise population estimates. Using thermal imaging, through thermal cameras fitted on unmanned aerial vehicles, to detect primates directly from the air, may prove a useful alternative to conventional great ape population surveys. This may be especially true for bonobos (Pan paniscus) which, due to their large body size and nesting behaviour, could provide a uniquely identifiable thermal signature. We trialled the use of a thermal drone to record bonobos in their natural environment in the Democratic Republic of Congo, as a first step towards using the technique to survey great apes. Bonobos were observed asleep in their nests during all surveys at different flight speeds and heights, showing potential for the use of thermal drones as a method to survey great apes.
Located in Library / RBINS Staff Publications 2022
Article Reference Detection of Bonobos (Pan Paniscus) in Tropical Rainforest Canopies Using Drone-Based Thermal Imaging: A First Step Towards Accurately Estimating Population Sizes?
Surveying great ape populations is time-consuming and costly, and often relies on generalised parameters, resulting in imprecise population estimates. Using thermal imaging, through thermal cameras fitted on unmanned aerial vehicles, to detect primates directly from the air, may prove a useful alternative to conventional great ape population surveys. This may be especially true for bonobos (Pan paniscus) which, due to their large body size and nesting behaviour, could provide a uniquely identifiable thermal signature. We trialled the use of a thermal drone to record bonobos in their natural environment in the Democratic Republic of Congo, as a first step towards using the technique to survey great apes. Bonobos were observed asleep in their nests during all surveys at different flight speeds and heights, showing potential for the use of thermal drones as a method to survey great apes.
Located in Library / RBINS Staff Publications 2022
Article Reference Detection of shipwrecks in ocean colour satellite imagery
Waterborne swath acoustic and airborne laser systems are the main methods used to detect and investigate fully submerged shipwreck sites. In the nearshore, waterborne techniques are compromised as search tools as their effective swath is a function of water depth, necessitating very close survey line spacing in shallow water, increasing cost accordingly. Additionally, in turbid coastal waters bathymetric LiDAR is ineffective as it relies on clear non-turbid water. Therefore, the nearshore turbid zone represents a challenging area for archaeologists in the search for fully submerged archaeological sites. In this study, we describe a new methodology to detect the presence of submerged shipwrecks using ocean colour satellite imagery in turbid waters. We demonstrate that wrecks generate Suspended Particulate Matter (SPM) concentration signals that can be detected by high-resolution ocean colour satellite data such as Landsat-8. Surface SPM plumes extend downstream for up to 4 km from wrecks, with measured concentrations ranging between 15 and 95 mg/l. The overall ratio between the plume and background SPM concentrations is about 1.4. During slack tidal phases sediments in suspension settle to create fluffy mud deposits near the seabed. Scour pits developed around wrecks act as sinks where fine-grained suspended material is preferentially deposited at slacks. The scour pits subsequently act as sources for suspended material when the bottom current increases after slacks. SPM plumes develop immediately before maximum ebb or flood current is reached, during maximum current and immediately after. Particulate matter is suspended in sufficient concentrations to be detected in ocean colour data. The ability to detect submerged shipwrecks from satellite remote sensors is of benefit to archaeological scientists and resource managers interesting in locating wrecks and investigating processes driving their evolution.
Located in Library / RBINS Staff Publications 2016
Article Reference Deux nouveaux gisements à otolithes de Téléostéens, dont une espèce nouvelle, dans l'Aquitanien continental du Midi de la France.
Located in Library / RBINS Staff Publications
Article Reference Deuxième note sur les Rugueux coloniaux de l'Eifelien supérieur et de la base du Givetien à Wellin (bord sud du Bassin de Dinant, Belgique)
Located in Library / RBINS Staff Publications 2016
Article Reference Deuxième note sur les téléostéens des Sables de Lede (Eocène belge)
Located in Library / RBINS Staff Publications
Article Reference Developing priority variables (“ecosystem Essential Ocean Variables” — eEOVs) for observing dynamics and change in Southern Ocean ecosystems
Abstract Reliable statements about variability and change in marine ecosystems and their underlying causes are needed to report on their status and to guide management. Here we use the Framework on Ocean Observing (FOO) to begin developing ecosystem Essential Ocean Variables (eEOVs) for the Southern Ocean Observing System (SOOS). An eEOV is a defined biological or ecological quantity, which is derived from field observations, and which contributes significantly to assessments of Southern Ocean ecosystems. Here, assessments are concerned with estimating status and trends in ecosystem properties, attribution of trends to causes, and predicting future trajectories. eEOVs should be feasible to collect at appropriate spatial and temporal scales and are useful to the extent that they contribute to direct estimation of trends and/or attribution, and/or development of ecological (statistical or simulation) models to support assessments. In this paper we outline the rationale, including establishing a set of criteria, for selecting eEOVs for the \SOOS\ and develop a list of candidate eEOVs for further evaluation. Other than habitat variables, nine types of eEOVs for Southern Ocean taxa are identified within three classes: state (magnitude, genetic/species, size spectrum), predator–prey (diet, foraging range), and autecology (phenology, reproductive rate, individual growth rate, detritus). Most candidates for the suite of Southern Ocean taxa relate to state or diet. Candidate autecological eEOVs have not been developed other than for marine mammals and birds. We consider some of the spatial and temporal issues that will influence the adoption and use of eEOVs in an observing system in the Southern Ocean, noting that existing operations and platforms potentially provide coverage of the four main sectors of the region — the East and West Pacific, Atlantic and Indian. Lastly, we discuss the importance of simulation modelling in helping with the design of the observing system in the long term. Regional boundary: south of 30°S.
Located in Library / RBINS Staff Publications 2016