scholarly journals IDENTIFICATION OF THE SPECTRAL CHARACTERISTICS OF SALTMARSH VEGETATION USING INDIRECT ORDINATION: A CASE STUDY FROM CHONGMING DONGTAN, SHANGHAI

2006 ◽  
Vol 30 (2) ◽  
pp. 252-260 ◽  
Author(s):  
GAO Zhan-Guo ◽  
◽  
ZHANG Li-Quan
Keyword(s):  
Spectral Characteristics ◽  
Indirect Ordination

Multi-scale ocean colour synergy products for coastal water quality monitoring

2020 ◽  
Author(s):  
Dimitry Van der Zande ◽  
Aida Alvera-Azcárate ◽  
Charles Troupin ◽  
João Cardoso Dos Santos ◽  
Dries Van den Eynde
Keyword(s):  
Spatial Resolution ◽  
Spectral Characteristics ◽  
Empirical Orthogonal Functions ◽  
High Temporal Resolution ◽  
Ocean Colour ◽  
Orthogonal Functions ◽  
Multi Scale ◽  
Medium Resolution ◽  
Sentinel 2

<p>High-quality satellite-based ocean colour products can provide valuable support and insights in the management and monitoring of coastal ecosystems. Today’s availability of Earth Observation (EO) data is unprecedented including medium resolution ocean colour systems (e.g. Sentinel-3/OLCI), high resolution land sensors (e.g. Sentinel-2/MSI) and geostationary satellites (e.g. MSG/SEVIRI). Each of these sensors offers specific advantages in terms of spatial, temporal or radiometric characteristics. In the Multi-Sync project, we developed advanced ocean colour products (i.e. remote sensing reflectance, turbidity, and chlorophyll a concentration) through the synergetic use of these multi-scale EO data taking advantage of spectral characteristics of traditional medium resolution sensors, the high spatial resolution of some land sensors and the high temporal resolution of geostationary sensors.</p><p>To achieve this goal a multi-scale DINEOF (Data Interpolating Empirical Orthogonal Functions) approach was developed to reconstruct missing data using empirical orthogonal functions (EOF), reduce noise and exploit spatio-temporal coherency by joining several spatial and temporal resolutions. Here we present the capacity of DINEOF to extract multi-scale information through the integration of Sentinel-3, Sentinel-2 and SEVIRI datasets.</p><p>The functionality of the advanced multi-scale products will be demonstrated in a case study for the Belgian Coastal Zone (BCZ) highly relevant to the user community: sediment transport modelling near the harbour of Zeebrugge in support of dredging operations. As stated in the OSPAR treaty (1992), Belgium is obliged to monitor and evaluate the effects of all human activities on the marine ecosystem. Dredging activities in and near Belgian harbors fall under this treaty and are performed daily to ensure accessibility of the port by ships. Optimization of these dredging activities requires monitoring data which is typically acquired through in situ observations or modelling data. In this case study we take advantage of Sentinel-3, Sentinel-2 and SEVIRI data characteristics to provide a satellite product that meets the end user requirements in terms of product quality and temporal/spatial resolution.</p><p> </p>

scholarly journals Strain Measurement on Cracks Using Fiber Bragg Gratings for Use in Aircraft Composite Skin Repairs

Aerospace ◽  
2020 ◽  
Vol 7 (9) ◽  
pp. 138
Author(s):  
Aris A. Ikiades
Keyword(s):  
Spectral Characteristics ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Stress Fields ◽  
Composite Repair ◽  
Local Stresses ◽  
Fbg Sensors ◽  
Critical Components ◽  
Co Doped

Fiber Bragg grating (FBG) sensors have been widely used for measurements of strain and temperature in a host of different applications, including aerospace in composite wings, fuselage structures, and other critical components. Here, we report on a method to measure highly localized intense stress fields, generated at the initialization point of a crack, or crack-tip, using Fiber Bragg Gratings (FBG) inscribed in highly photosensitive hydrogenated germanium and boron co-doped fiber. From the spectral characteristics of short and long FBGs, bonded on a test aluminum coupon with a crack, which simulated damaged skins of an aircraft, the local stresses near the cracks were measured and assessed. As a case study, bespoke composite repair patches were designed and bonded on a coupon, incorporating a number of gratings to monitor the stress distribution with applied force in the composite patch, near the crack.

scholarly journals Intensity Data Correction for Long-Range Terrestrial Laser Scanners: A Case Study of Target Differentiation in an Intertidal Zone

2019 ◽  
Vol 11 (3) ◽  
pp. 331 ◽  
Author(s):  
Kai Tan ◽  
Jin Chen ◽  
Weiwei Qian ◽  
Weiguo Zhang ◽  
Fang Shen ◽  
...  
Keyword(s):  
Intertidal Zone ◽  
Incidence Angle ◽  
Spectral Characteristics ◽  
Laser Scanner ◽  
Indoor Environments ◽  
Intensity Data ◽  
Improved Method ◽  
Long Distance ◽  
Target Characteristics

The intensity data recorded by a terrestrial laser scanner (TLS) contain spectral characteristics of a scanned target and are mainly influenced by incidence angle and distance. In this study, an improved implementable method is proposed to empirically correct the intensity data of long-distance TLSs. Similar to existing methods, the incidence angle–intensity relationship is estimated using some reference targets scanned in the laboratory. By contrast, due to the length limit of indoor environments and the laborious data processing, the distance–intensity relationship is derived by selecting some natural homogeneous targets with distances covering the entire distance scale of the adopted long-distance TLS. A case study of intensity correction and point cloud classification in an intertidal zone in Chongming Island, Shanghai, China, is conducted to validate the feasibility of the improved method by using the intensity data of a long-distance TLS (Riegl VZ-4000). Results indicate that the improved method can accurately eliminate the effects of incidence angle and distance on the intensity data of long-distance TLSs; the coefficient of variation of the intensity data for the targets in the study intertidal zone can be reduced by approximately 54%. The classification results of the study intertidal zone show that the improved method can effectively eliminate the variations caused by the incidence angle and distance in the original intensity data of the same target to obtain a corrected intensity that merely depends on target characteristics for improving classification accuracy by 49%.

scholarly journals Conodont thermometry by Raman spectroscopy on carbonaceous material: a case study from the Northern Calcareous Alps (Mürzalpen Nappe, Eastern Alps)

2020 ◽  
Vol 113 (1-2) ◽  
pp. 201-210
Author(s):  
Gerd Rantitsch ◽  
Gerhard Bryda ◽  
Hans-Jürgen Gawlick
Keyword(s):  
Raman Spectroscopy ◽  
Spectral Characteristics ◽  
Carbonaceous Material ◽  
Eastern Alps ◽  
Northern Calcareous Alps ◽  
Carbonaceous Matter ◽  
Northern Calcareous ◽  
Temperature Range ◽  
Color Alteration

AbstractCarnian metapelites from the southeastern segment of the Mürzalpen Nappe (Northern Calcareous Alps, Eastern Alps) were heated to 280-310 °C, estimated by Raman spectroscopy of carbonaceous material (RSCM). This temperature range is correlated to a Color Alteration Index of 5.0-6.5, determined on conodonts from adjacent Anisian to Norian carbonates. Average RSCM temperatures estimated on the conodonts are biased towards higher temperatures. The spectral characteristics of the conodont apatite suggest a composition altered during progressive recrystallization, influencing the band parameters of the included carbonaceous matter. Consequently, accurate conodont RSCM thermometry needs an assessment of apatite alteration.

The spectral characteristics and remote detection of lunar Mg-spinel: A case study of Tycho Crater

2016 ◽  
Vol 46 (2) ◽  
pp. 029607
Author(s):  
Jian CHEN ◽  
Jiang ZHANG ◽  
LingZhi SUN ◽  
ZongCheng LING ◽  
Bo LI
Keyword(s):  
Spectral Characteristics ◽  
Remote Detection

scholarly journals Identifying, Examining, and Planning Areas Protected from Light Pollution. The Case Study of Planning the First National Dark Sky Park in Greece

2019 ◽  
Vol 11 (21) ◽  
pp. 5963 ◽  
Author(s):  
Andreas Papalambrou ◽  
Lambros T. Doulos
Keyword(s):  
Urban Areas ◽  
Spectral Characteristics ◽  
Natura 2000 ◽  
Light Pollution ◽  
Wide Field ◽  
Park Planning ◽  
Complete Study ◽  
Design Selection ◽  
Sparse Population

Light pollution is a type of pollution that climaxes in cities and occurs increasingly away from them, due to the increase of artificial lighting and inappropriate lighting design (selection of luminaires, aiming, illuminance/luminance levels, and spectral characteristics). Increasingly, light pollution also affects the countryside due to local lighting but also distant lighting propagating from urban areas. This has a significant impact on ecosystems and astronomical observing sites. This work analyzes the main facts about light pollution (causes, impact, and solutions) and studies the methods, parameters, and special requirements for planning of light pollution protected areas. This dark sky park planning methodology is implemented as a case study in mount Parnon which has been selected due to its significance as a Natura 2000 protected area and because it is Greece’s most popular astronomical observing site. Mount Parnon is located close to two major cities as well as significant highways, however the site itself remains dark due to its sparse population. Planning a dark sky park involves a complete study of facts regarding the specific site. Existing lighting installations are surveyed in detail by recording types of luminaires and lamps and recording their positions in a map. Lighting illuminance levels are measured by photometers and spectra are analyzed using a spectrometer. Sky brightness levels measurements are performed using specialized photometers and light pollution origins are traced using wide-field photography. Finally, a proposal is made for a dark sky park scheme suited to the specific case of the site.

Study on the Spectral Characteristics of Black-Odorous Water: A Case Study of Shenzhen City, China

2021 ◽  
Vol 42 (9) ◽  
pp. 3302-3325
Author(s):  
Xue Zhang ◽  
Jiaguo Li ◽  
Yanyang Hu ◽  
Li Zhu ◽  
Ning Zhang
Keyword(s):  
Spectral Characteristics ◽  
Shenzhen City

scholarly journals Spectral characteristics and spatial smoothing of wind power – a case study of the Faroe Islands

2020 ◽  
Vol 29 (6) ◽  
pp. 427-438
Author(s):  
Turið Poulsen ◽  
Hans Georg Beyer
Keyword(s):  
Wind Power ◽  
Spectral Characteristics ◽  
Faroe Islands ◽  
Spatial Smoothing

scholarly journals Adaption of the MODIS aerosol retrieval algorithm by airborne spectral surface reflectance measurements over urban areas: a case study

2015 ◽  
Vol 8 (7) ◽  
pp. 7335-7371
Author(s):  
E. Jäkel ◽  
B. Mey ◽  
R. Levy ◽  
X. Gu ◽  
T. Yu ◽  
...  
Keyword(s):  
Urban Areas ◽  
Spectral Characteristics ◽  
Mean Difference ◽  
Retrieval Algorithm ◽  
Surface Reflectance ◽  
Beijing Area ◽  
Airborne Measurements ◽  
Aerosol Retrieval ◽  
Modis Aod

Abstract. MODIS retrievals of the aerosol optical depth (AOD) are biased over urban areas, where surface reflectance is not well characterized. Since the operational MODIS aerosol retrieval for dark targets assumes fixed spectral slopes to calculate the surface reflectance at 0.47 μm, the algorithm may fail in urban areas with different spectral characteristics of the surface reflectance. To investigate this bias we have implemented variable spectral slopes into the operational MODIS aerosol algorithms of Collection 5 (C5) and C6. The variation of slopes is based on airborne measurements of surface reflectances over the city of Zhongshan, China. AOD retrieval results of the operational and the modified algorithms were compared for a MODIS measurement over Zhongshan. For this case slightly lower AOD values were derived using the modified algorithm. The retrieval methods were additionally applied to MODIS data of the Beijing area for a period between 2010–2014 when also AERONET data were available. A reduction of the differences between the AOD retrieved using the modified C5 algorithm and AERONET was found, whereby the mean difference from 0.31 ± 0.11 for the operational C5 and 0.18 ± 0.12 for the operational C6 where reduced to a mean difference of 0.09 ± 0.18 by using the modified C5 retrieval. Furthermore, the sensitivity of the MODIS AOD retrieval for several surface types was investigated. Radiative transfer simulations were performed to model reflectances at top of atmosphere for predefined aerosol properties. The reflectances were used as input for the retrieval methods. It is shown that the operational MODIS AOD retrieval over land reproduces the AOD reference input of 0.85 for dark surface types [retrieved AOD = 0.87 (C5)]. An overestimation of AOD = 0.99 is found for urban surfaces, whereby the modified C5 algorithm shows a good performance with a retrieved value of AOD = 0.86.

scholarly journals SEA FOG DETECTION BASED ON DYNAMIC THRESHOLD ALGORITHM AT DAWN AND DUSK TIME

2019 ◽  
Vol XLII-3/W9 ◽  
pp. 159-163 ◽  
Author(s):  
J. H. Wan ◽  
L. Jiang ◽  
Y. F. Xiao ◽  
H. Sheng
Keyword(s):  
Remote Sensing ◽  
High Frequency ◽  
Spectral Characteristics ◽  
Dynamic Threshold ◽  
Polar Orbit ◽  
Sea Fog ◽  
Threshold Algorithm ◽  
Study Results ◽  
Fog Detection

Abstract. Dawn and dusk time is the high frequency period of sea fog occurrence, which is very important for all-day sea fog remote sensing detection. Most polar orbit satellites are limited by time resolution and transit time, and can not detect sea fog at dawn and dusk. Based on the Himawari-8 geostationary satellite data and the analysis of the spectral characteristics of sea fog at dawn and dusk, this paper determines the variation law of the reflectivity and brightness temperature of sea fog at dawn and dusk, chooses sensitive bands, sets the detection index of sea fog and its corresponding dynamic threshold, and realizes the detection of sea fog at dawn and dusk. The case study results indicate that our dynamic threshold algorithm can effectively detect the sea fog at dawn and dusk.

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