Mapping mineral chemistry of a lateritic outcrop in new Caledonia through generalized regression using Sentinel-2 and field reflectance spectra

Despite the necessary trade-offs between spatial and temporal resolution, remote sensing is an effective approach to monitor macroalgae blooms, understand their origins and anticipate their developments. Monitoring of small tropical lagoons is challenging because they require high resolutions. Since 2017, the Sentinel-2 satellites has provided new perspectives, and the feasibility of monitoring green algae blooms was investigated in this study. In the Poé-Gouaro-Déva lagoon, New Caledonia, recent Ulva blooms are the cause of significant nuisances when beaching. Spectral indices using the blue and green spectral bands were confronted with field observations of algal abundances using images concurrent with fieldwork. Depending on seabed compositions and types of correction applied to reflectance data, the spectral indices explained between 1 and 64.9% of variance. The models providing the best statistical fit were used to revisit the algal dynamics using Sentinel-2 data from January 2017 to December 2019, through two image segmentation approaches: unsupervised and supervised. The latter accurately reproduced the two algal blooms that occurred in the area in 2018. This paper demonstrates that Sentinel-2 data can be an effective source to hindcast and monitor the dynamics of green algae in shallow lagoons.

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Über die Natur der Cu2+-Zentren im NH4Cl - die spektroskopische Untersuchung von Cu2+-dotiertem Hg(NH3)2Cl2/The Nature of the Cu2+ Centres in NH4Cl - a Spectroscopic Investigation of Cu2+ Doped Hg(NH3)2Cl2

Zeitschrift für Naturforschung B ◽

10.1515/znb-1992-0403 ◽

1992 ◽

Vol 47 (4) ◽

pp. 465-469 ◽

Cited By ~ 9

Author(s):

G. Steffen ◽

U. Kaschuba ◽

M. A. Hitchman ◽

D. Reinen

Keyword(s):

Ground State ◽

Spectroscopic Investigation ◽

Reflectance Spectra ◽

Ligand Field ◽

Field Reflectance

The preparation of Hg(NH3)2Cl2 doped with a small amount of Cu2+ is reported. The EPR and ligand field reflectance spectra indicate the presence of “CuCl4(NH3)2” polyhedra with a compressed tetragonal geometry and confirm, that the centres in Cu2+ doped NH4Cl possess the same geometry - as postulated earlier. The Cu2+ centres in Hg(NH3)2Cl2 are less compressed than those in NH4Cl, however, as could be deduced from the copper(II) hyperfine values, which are strongly influenced by the quite different admixture of the metal 4s orbital into the Alg (dz2) ground state in the two cases, and from the comparable energies of the d - d transitions.

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Using Optical Water Types to Monitor Changes in Optically Complex Inland and Coastal Waters

Remote Sensing ◽

10.3390/rs11192297 ◽

2019 ◽

Vol 11 (19) ◽

pp. 2297 ◽

Cited By ~ 6

Author(s):

Kristi Uudeberg ◽

Ilmar Ansko ◽

Getter Põru ◽

Ave Ansper ◽

Anu Reinart

Keyword(s):

Remote Sensing ◽

Coastal Waters ◽

Atmospheric Correction ◽

Suspended Sediments ◽

Reflectance Spectra ◽

Water Type ◽

Colored Dissolved Organic Matter ◽

Water Color ◽

Sentinel 2

The European Space Agency’s Copernicus satellites Sentinel-2 and Sentinel-3 provide observations with high spectral, spatial, and temporal resolution which can be used to monitor inland and coastal waters. Such waters are optically complex, and the water color may vary from completely clear to dark brown. The main factors influencing water color are colored dissolved organic matter, phytoplankton, and suspended sediments. Recently, there has been a growing interest in the use of the optical water type (OWT) classification in the remote sensing of ocean color. Such classification helps to clarify relationships between different properties inside a certain class and quantify variation between classes. In this study, we present a new OWT classification based on the in situ measurements of reflectance spectra for boreal region lakes and coastal areas without extreme optical conditions. This classification divides waters into five OWT (Clear, Moderate, Turbid, Very Turbid, and Brown) and shows that different OWTs have different remote sensing reflectance spectra and that each OWT is associated with a specific bio-optical condition. Developed OWTs are distinguishable by both the MultiSpectral Instrument (MSI) and the Ocean and Land Color Instrument (OLCI) sensors, and the accuracy of the OWT assignment was 95% for both the MSI and OLCI bands. To determine OWT from MSI images, we tested different atmospheric correction (AC) processors, namely ACOLITE, C2RCC, POLYMER, and Sen2Cor and for OLCI images, we tested AC processors ALTNNA, C2RCC, and L2. The C2RCC AC processor was the most accurate and reliable for use with MSI and OLCI images to estimate OWTs.

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Tieftemperatur-Remissionsspektren oktaedrisch koordinierter Cu2+ -Ionen im Ligandenfeldbereich / Low temperature reflectance spectra of octahedrally coordinated Cu2+-ions in solids

Zeitschrift für Naturforschung A ◽

10.1515/zna-1973-3-421 ◽

1973 ◽

Vol 28 (3-4) ◽

pp. 464-471 ◽

Cited By ~ 17

Author(s):

J. Grefer ◽

D. Reinen

Keyword(s):

Reflectance Spectra ◽

Ligand Field ◽

Teller Distortion ◽

Square Planar ◽

Jahn Teller ◽

Jahn Teller Effect ◽

Field Formalism ◽

Field Reflectance ◽

Host Lattices ◽

Overlap Model

AbstractThe ligand field reflectance spectra of octahedrally coordinated Cu2+-ions in different host lattices and at different temperature (300 °K - 4 °K) are critically compared. Especially the band shifts with decreasing temperature are analysed with respect to transitions from a dynamical to a static Jahn-Teller effect (macroscopic Jahn -Teller distortion of the lattice). In addition the square planar coordination of Cu2+ is discussed and alternative descriptions in the crystal field formalism and the angular overlap model are given.

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Deriving chlorophyll fluorescence emissions of vegetation canopies from high resolution field reflectance spectra

10.1117/12.631159 ◽

2005 ◽

Author(s):

Elizabeth M. Middleton ◽

Lawrence A. Corp ◽

Craig S. Daughtry ◽

Petya K. Entcheva Campbell ◽

L. Maryn Butcher

Keyword(s):

Chlorophyll Fluorescence ◽

High Resolution ◽

Reflectance Spectra ◽

Vegetation Canopies ◽

Field Reflectance

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Estimating wheat biochemical concentration from field reflectance spectra

10.1117/12.466720 ◽

2003 ◽

Author(s):

Liangyun Liu ◽

Bing Zhang ◽

Lanfen Zheng ◽

Qingxi Tong

Keyword(s):

Reflectance Spectra ◽

Field Reflectance

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Validation airborne visible-infrared imaging spectrometer data at Ray Mine, Arizona

Environmental and Engineering Geoscience ◽

10.2113/gseegeosci.6.3.187 ◽

2000 ◽

Vol 6 (3) ◽

pp. 187-200 ◽

Cited By ~ 3

Author(s):

Harold R. Lang ◽

Steven M. Baloga

Keyword(s):

Infrared Imaging ◽

Imaging Spectroscopy ◽

Reflectance Spectra ◽

Open Pit ◽

Imaging Spectrometer ◽

Diagnostic Statistics ◽

Field Reflectance ◽

Surface Mineralogy ◽

Spectrometer Data ◽

Comparable Quality

Abstract The fundamental promise of imaging spectroscopy is to provide surface mineralogy based on remotely-acquired, gridded reflectance spectra of comparable quality to those from high resolution laboratory and field spectrometers. For regulatory and environmental monitoring, validating imaging spectrometer data is a major issue with this emerging technology. In this paper we validate 1997 Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) reflectance spectra covering 0.4 mu m-2.4 mu m at a stable, flat, manmade target at Ray Mine, Arizona, for EPA/NASA assessment of the utility of remote sensing for monitoring acid drainage from an active open pit copper mine. For validation, we a) compare qualitatively, laboratory and field reflectance spectra with corresponding AVIRIS spectra; b) compare quantitatively, mineralogically diagnostic statistics from field spectra with the same statistics from field spectra with the same statistics from AVIRIS spectra; and c) demonstrate a methodology for validating imaging spectrometer data for environmental applications.

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Shallow Water Bathymetry Retrieval Using a Band-Optimization Iterative Approach: Application to New Caledonia Coral Reef Lagoons Using Sentinel-2 Data

Remote Sensing ◽

10.3390/rs13204108 ◽

2021 ◽

Vol 13 (20) ◽

pp. 4108

Author(s):

Sélim Amrari ◽

Emmanuel Bourassin ◽

Serge Andréfouët ◽

Benoit Soulard ◽

Hugues Lemonnier ◽

...

Keyword(s):

New Caledonia ◽

Ground Truth ◽

Absolute Error ◽

Depth Range ◽

Band Ratio ◽

Multiple Band ◽

Validation Procedure ◽

World Heritage Area ◽

Bottom Depth ◽

Sentinel 2

To achieve high accuracy bathymetry retrieval using remote sensing images with robust performance in a 0 to 25 m-deep lagoon with sharp bottom depth variations, a new Iterative Multiple Band Ratio (IMBR) algorithm is tested against known Multiple Band Ratio (MBR) and Single Band Ratio (SBR) algorithms. The test was conducted using the five multispectral bands, at 10 to 60 m resolution, of a Sentinel-2 image of the 25 km2 Poe lagoon, a UNESCO World Heritage Area. The IMBR approach requires training datasets for the definitions of depth threshold at which optimal band ratios vary. IMBR achieved accuracy, quantified with an original block cross-validation procedure across the entire depth range reached a mean absolute error of 46.0 cm. It compares very favorably against MBR (78.3 cm) and the various SBR results (188–254 cm). The method is suitable for generalization to other sites pending a minimal ground-truth dataset crossing all the depth range being available. We stress that different users may need different precisions and can use MBR or SBR algorithms for their applications. For the hydrodynamic modelling applications that are developing in New Caledonia, the IMBR solutions applied to Sentinel imagery are optimal.

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Chlorophyll Fluorescence Emissions of Vegetation Canopies From High Resolution Field Reflectance Spectra

2006 IEEE International Symposium on Geoscience and Remote Sensing ◽

10.1109/igarss.2006.1042 ◽

2006 ◽

Cited By ~ 3

Author(s):

E. Middleton ◽

L. Corp ◽

C. Daughtry ◽

P. Campbell

Keyword(s):

Chlorophyll Fluorescence ◽

High Resolution ◽

Reflectance Spectra ◽

Vegetation Canopies ◽

Field Reflectance

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Intra-oceanic subduction initiation recorded by the metamorphic sole of the New Caledonia ophiolite: petrological, structural and age constraints

10.5194/egusphere-egu2020-11835 ◽

2020 ◽

Author(s):

Bénédicte Cenki-Tok ◽

Derya Gürer ◽

Vasileios Chatzaras ◽

Julien Collot ◽

Fernando Corfu ◽

...

Keyword(s):

Plate Tectonics ◽

New Caledonia ◽

Time History ◽

Mineral Chemistry ◽

Published Data ◽

Spreading Ridge ◽

Plate Interface ◽

Subduction Initiation ◽

Grain Size Distributions ◽

History Of

Subduction initiation is commonly identified as a major enigma in plate tectonics. Attention to subduction initiation is growing in the community, as is our understanding of the sequences of geologic events that precede and postdate this critical stage of the Wilson cycle. Nevertheless, the direct triggers of subduction initiation and their regional to global consequences remain uncertain. The New Caledonia ophiolite has formed in a supra-subduction zone setting in the vicinity of an active spreading centre. The metamorphic sole, which represents the ancient subduction interface, is locally preserved beneath the ophiolite. Unravelling its tectono-metamorphic record is essential in order to determine the timing of subduction initiation and the tectonic processes operating at the plate interface during the early stages of subduction.&#160; We have sampled and studied amphibole-bearing rocks of the metamorphic sole that crop out in three newly found and three previously known localities that are scattered across the island (160 km * 50 km in size). The amphibolites form laterally discontinuous meter-size lenses that crop out within or beneath the serpentinite sole at the base of the ophiolite nappe.&#160; Preliminary U-Pb zircon ID-TIMS geochronology yields a crystallization age of 56&#177;1 Ma in agreement, but with a narrower timespan compared to previously published data (Cluzel et al., 2012).&#160; We use whole-rock geochemistry, mineral chemistry and thermodynamic modelling to constrain the Pressure-Temperature-time history of the amphibolites.&#160; Microstructural data such as dominant deformation mechanisms, crystallographic preferred orientations, grain size distributions determined by EBSD allow to constrain the deformation processes and rheological behavior of the amphibolites during subduction infancy.&#160;Cluzel, D., Jourdan, F., Meffre, S., Maurizot, P., and Lesimple, S., 2012. The metamorphic sole of New Caledonia ophiolite: 40Ar/39Ar, U-Pb, and geochemical evidence for subduction inception&#160;at a spreading ridge. Tectonics, VOL. 31, TC3016, doi:10.1029/2011TC003085.

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