Validation of Landsat-8 and Sentinel-2 algorithms for atmospheric correction on Lake Geneva

Sonia Joëlle Dupuis
2017
Student project

Abstract

Remote-sensing of water surfaces such as large lakes is a useful tool for monitoring and understanding large-scale processes. Suspended particles in lakes can have various sources such as autochthonously produced organic matter, urban or agricultural runoff or rivers inflows. Understanding their sources and impacts on natural waters is highly important as they are the mirror of the ecological well being. As suspended solids can be retrieved by remote-sensing based on their reflectances, satellite images are an important tool to study the lake and detecting important processes and events. Before using the reflectances measured by the sensor for monitoring lakes, atmospheric corrections have to be applied on the image for retrieving accurate data. This project compares three different algorithms for atmospheric corrections, namely Acolite developed in Belgium, OPERA developed at Vito and C2RCC designed by Brockmann Consulting, applied on the case study, the Lake of Geneva. The resulting reflectances from the different algorithm settings are compared to the in-situ water-leaving reflectance measurements. Additionally, the total suspended matter concentrations derived from the output reflectances were validated with in-situ concentrations. C2RCC with elevation indication performs a good atmospheric correction and yield good particulate concentrations by non-ideal atmospheric conditions. Acolite with a linear parameter of 9.5 gives good results by perfect weather conditions. This projects depicts guidelines and recommendations for performing atmospheric corrections over the Lake Geneva with these algorithms.

Official source

https://infoscience.epfl.ch/record/232033?ln=en

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Sonia Joëlle Dupuis
2017
Student project

Abstract

Official source

https://infoscience.epfl.ch/record/232033?ln=en

About this result

Related concepts (18)

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Related publications (15)

Related publications

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An improved understanding of surface transport processes is necessary to predict sediment, pollutant and phytoplankton patterns in large lakes. Lake surface water temperature (LSWT) which may spatially and temporarily vary over the lake surface reflects meteorological and climatological forcing more than any other physical lake parameter. There are different data sources for LSWT mapping, including remote sensing and in situ measurements. The available satellite data might be suitable for detecting the large-scale thermal patterns, but not the meso- or small scale processes. Lake surface thermography, investigated in this study, has finer resolution compared to satellite images. Thermography at the meso-scale provides the ability to ground-truth satellite imagery over scales of one to several satellite image pixels. On the other hand, thermography data can be used as a control in schemes to upscale local measurements that account for the surface energy fluxes and vertical energy budget. Independently, since such data can be collected at high frequency, they can be also useful in capturing the surface signatures of meso-scale eddies and thus to quantify mixing processes. In the present study, we report results from a Balloon Launched Imaging and Monitoring Platform (BLIMP), which was developed in order to measure the LSWT at meso-scale. The BLIMP consists of a small balloon which is tethered to a boat and equipped with the thermal and RGB cameras, as well as other instrumentation for location and communication. Several deployments were carried out on Lake Geneva. In a typical deployment, the BLIMP is towed by a boat, and collects high frequency data from different heights (i.e., spatial resolutions) and locations. Simultaneous ground-truthing of the BLIMP data is achieved using an autonomous craft that collects a variety of data, including in situ surface/near surface temperatures, radiation and meteorological data in the area covered by the BLIMP images. With suitable scaling, our results show good consistency between in situ, BLIMP and concurrent satellite data. In addition, the BLIMP thermography reveals (hydrodynamically-driven) structures in the LSWT – an obvious example being mixing of river discharges.

2015

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The potential impact of Tire and Road Wear Particles (TRWP) on aquatic organisms has recently gained attention since the occurrence of TRWP in the aquatic environment has been demonstrated in surface water and sediments of numerous regions. However, data regarding the bioavailability and toxicity of contaminants associated with these particles are still lacking. Several metals enter in the composition of tires including Zinc, used as a catalyst during the vulcanization process of rubber. This study aimed (i) to characterize the elemental composition of Cryogenically Milled Tire Tread (CMTT) and TRWP and (ii) to assess the solubilization potential of inorganic contaminants from CMTT and TRWP in Simulated Gastric Fluids (SFG) and Simulated Intestinal Fluids (SIF) designed to mimic Oncorhynchus mykiss (Rainbow Trout) gut conditions. Our results show an important difference in the elemental composition of CMTT and TRWP due to the input of elements such as Ti, Cr, Mn, Sr, Ba and Pb from the road constituent to the TRWP. In vitro digestion experiments of both CMTT and TRWP showed that solubilization of all metals were enhanced by up to 10-fold in simulated gut fluids compared to solubilization in phosphate buffer solution. Solubilization kinetics to the SGF and SIF were biphasic with a higher solubilization rate of elements within the first hour and a slower solubilization rate up to 26h. For most metals, solubilization rates were higher for TRWP than for CMTT. After digestion time of 26h, from 1% (Co) to 10% (Zn) of total metal in CMTT were solubilized in the gut fluids and the concentration of metals were about 1 – 100 µg/L except for Zn with 7000 µg/L. Our results emphasise the importance of pH, bile surfactants and organic matter in the solubilization of metals from TRWP and brings new insights on the bioavailability of inorganic pollutants from TRWP.

2020

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The potential impact of Tire and Road Wear Particles (TRWP) on aquatic organisms has recently gained attention since the occurrence of TRWP in the aquatic environment has been observed in surface water and sediments of numerous regions. Moreover, the ingestion of TRWP by aquatic species, including fish, has recently been demonstrated. However, data regarding the bioavailability and toxicity of contaminants associated with these particles are still lacking. This study aimed (i) to characterize the solubilization potential of metals and PAHs from tire particles and TRWP in Simulated Gastric Fluids (SFG) and Simulated Intestinal Fluids (SIF) designed to mimic Oncorhynchus mykiss (Rainbow Trout) gut conditions and (ii) to assess the impact of influencing factors such as co-ingestion of natural food organic matter on the compounds solubilization. Our results showed that solubilization of all metals and PAHs were enhanced by up to 10-fold in simulated gut fluids compared to solubilization in the control (phosphate buffer saline solution). Zn was highly solubilized after an in-vitro digestion of 24-h with a final concentration in SIF of 3,2 µg.L-1 corresponding to 23 % of the total Zn concentration in TRWP. Five PAHs (Fluoranthene, Phenanthrene, Pyrene, Benzo (e) Pyrene and Benzo (g,h,i) perylene) were quantified in SIF after an incubation time of 24-h and the concentration of individual PAHs in SIF ranged from 42 to 3092 ng.L-1 which represented 0,4 – 1,5 % of their total concentration measured in tire particles. Metals were highly solubilized by the acidic SGF (pH = 2) but only a weak solubilization was observed in neutral SIF (pH = 7,4). Contrastingly, PAHs were not solubilized in SGF and highly solubilized in SIF which was proved to contain high quantities of proteins and surfactants forming micelles. This emphasise the importance of pH in the solubilization of metals and of bile surfactants and organic matter in the solubilization of PAHs from TRWP and brings new insights on the bioavailability of metals and organic pollutants from TRWP. Overall, our results demonstrate the importance of accounting for the ingestion of TRWP as an important route of exposure to metals and PAHs for aquatic organisms. As the solubilization of potential toxic compounds was greatly enhanced by the gut fluids and leads to bioavailability of these compounds, further studies investigating the uptake by the epithelial cells and transfer throughout the whole organism will be performed.

2021

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2015

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2021