scholarly journals OIL SLICK FATE IN A REGION OF STRONG TIDAL CURRENTS

1974 ◽  
Vol 1 (14) ◽  
pp. 130
Author(s):  
G. Drapeau ◽  
W. Harrison ◽  
W. Bien ◽  
P. Leinonen
Keyword(s):  
Remote Sensing ◽  
Mathematical Models ◽  
Oil Spill ◽  
Field Measurements ◽  
Tidal Currents ◽  
Lawrence Estuary ◽  
Oil Slick ◽  
Scale Models ◽  
St Lawrence Estuary ◽  
Made In

This study examines the drifting, spreading and aging of small slicks of crude oil in the middle St. Lawrence Estuary. This region was chosen because it is well documented with field measurements, hydraulic scale models, and mathematical models; and also because it is becoming a strategic area for the development of supertanker ports for 300,000 and possibly 500,000 ton tankers. Two controlled releases of Venezuelan crude (370 and 800 litres) were made in November 1972, as ice began to form in the St. Lawrence Estuary. The experiments were supported by the Canada Centre for Remote Sensing which carried out extensive airborne monitoring. The results indicate that it is impossible either to recover or to disperse small spills of oil in this region of strong tidal currents. Models also predict slick motion poorly. The alternative is to construct slick-drift roses that will indicate areas of expected beaching and assist in deployment of oil-spill clean-up technology.

scholarly journals Spatial variations in CO<sub>2</sub> fluxes in the Saguenay Fjord (Quebec, Canada) and results of a water mixing model

2020 ◽  
Vol 17 (2) ◽  
pp. 547-566 ◽  
Author(s):  
Louise Delaigue ◽  
Helmuth Thomas ◽  
Alfonso Mucci
Keyword(s):  
Surface Waters ◽  
Brackish Water ◽  
Field Measurements ◽  
Mixing Model ◽  
Isotopic Tracers ◽  
Lawrence Estuary ◽  
Relative Contribution ◽  
Saguenay Fjord ◽  
Spring Freshet ◽  
St Lawrence Estuary

Abstract. The Saguenay Fjord is a major tributary of the St. Lawrence Estuary and is strongly stratified. A 6–8 m wedge of brackish water typically overlies up to 270 m of seawater. Relative to the St. Lawrence River, the surface waters of the Saguenay Fjord are less alkaline and host higher dissolved organic carbon (DOC) concentrations. In view of the latter, surface waters of the fjord are expected to be a net source of CO2 to the atmosphere, as they partly originate from the flushing of organic-rich soil porewaters. Nonetheless, the CO2 dynamics in the fjord are modulated with the rising tide by the intrusion, at the surface, of brackish water from the Upper St. Lawrence Estuary, as well as an overflow of mixed seawater over the shallow sill from the Lower St. Lawrence Estuary. Using geochemical and isotopic tracers, in combination with an optimization multiparameter algorithm (OMP), we determined the relative contribution of known source waters to the water column in the Saguenay Fjord, including waters that originate from the Lower St. Lawrence Estuary and replenish the fjord's deep basins. These results, when included in a conservative mixing model and compared to field measurements, serve to identify the dominant factors, other than physical mixing, such as biological activity (photosynthesis, respiration) and gas exchange at the air–water interface, that impact the water properties (e.g., pH, pCO2) of the fjord. Results indicate that the fjord's surface waters are a net source of CO2 to the atmosphere during periods of high freshwater discharge (e.g., spring freshet), whereas they serve as a net sink of atmospheric CO2 when their practical salinity exceeds ∼5–10.

REAL-TIME PROCESSING OF OIL SPILL REMOTE SENSING DATA1

1987 ◽  
Vol 1987 (1) ◽  
pp. 71-73
Author(s):  
Yvon J. F. Le Guen ◽  
Marc Brussieux ◽  
Rolland Burkhalter
Keyword(s):  
Remote Sensing ◽  
Image Processing ◽  
Oil Spill ◽  
Infrared Emissivity ◽  
Real Time Processing ◽  
Time Processing ◽  
Oil Slick ◽  
Processing Program ◽  
Thermal Infrared Imagery

ABSTRACT The good quality of thermal infrared imagery and the relation between infrared emissivity and the thickness of an oil slick have led to the development of a visualizing rack and an image processing program. This system, tested on board a surveillance aircraft, has permitted on-site estimation within 20 seconds of the total volume of a 28 cubic meter slick with less than 15% error.

Use of Geo-Informatics on Nearshore Management in Oil Spill Accidents

2001 ◽  
Vol 2001 (1) ◽  
pp. 489-495
Author(s):  
Shintaro Goto ◽  
Sang-Woo Kim
Keyword(s):  
Remote Sensing ◽  
Information Management ◽  
Oil Spill ◽  
Warning System ◽  
Remote Sensing Data ◽  
Information Provision ◽  
Interim Result ◽  
Oil Slick ◽  
Recovery Support

ABSTRACT From the lessons after the Nakhodka oil spill in January 1997, oil slick detection by using remote-sensing data and assimilating the data to the simulation program is important for monitoring the oil drift pattern. For this object, the authors are going to construct the oil spill warning system for estimating the oil drift pattern using a remote-sensing/numerical simulation model. Additionally, they plan to use this system for restoring oil spill damage domestically, such as estimating the ecological damage and making the priority for restoring the oil spilled shoreline. This report is intended to summarize the role of geo-informatics in the oil spill accident by not only paying attention to the effect of information provision/information management via the map, but also reporting the interim result in part based on the details discussed in the processes of recovery support and environmental impact assessment during the Nakhodka accident.

Transitioning SAR-derived Oil Spill Thickness Measurements into an Operational Context

2021 ◽  
Author(s):  
Benjamin Holt ◽  
Frank Monaldo ◽  
Cathleen Jones ◽  
Oscar Garcia
Keyword(s):  
Wind Speed ◽  
Oil Spill ◽  
Field Measurements ◽  
Low Noise ◽  
Sensor Data ◽  
Oil Slick ◽  
Field Campaigns ◽  
L Band ◽  
Sar Imagery ◽  
Oil Thickness

&lt;p&gt;We describe an effort to develop a quantifiable approach for determining the thicker components of oil spills using microwave synthetic aperture radar (SAR) imagery that can be utilized in an operational context to guide clean-up efforts. The presence of mineral oil on the surface can suppress the SAR returns in two ways. First, surface oil dampens the capillary waves making those areas darker in SAR imagery, an effect that been used to determine oil extent. The second is by modifying the dielectric properties of the surface from those of clean seawater to either pure oil or a mixture of oil and water as the oil weathers and thickens to form an emulsion. The emulsion provides an intermediate conductive surface layer between the highly conductive ocean itself and the very low, &amp;#8216;radar transparent&amp;#8217; sheen layers, resulting in a further reduction in the radar returns for areas with thicker oil within an inhomogeneous oil slick. The challenges are to quantify the thickness and conditions for which this thicker layer becomes separable from the thinner oil, determine whether multiple thicker components can be identified, identify which airborne and spaceborne SAR systems can be used for this purpose, and determine under what range of environmental conditions, particularly wind speed, it is possible.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;We are planning to hold field campaigns with in situ measurements and SAR and multispectral remote sensor data collections from drones, aircraft, and satellites. The field measurements include surface collections of oil, underwater spectrophotometry, and drone-based infrared, ultraviolet, and optical collections.&amp;#160; Coincident with the field measurements, the airborne L-band NASA-UAVSAR SAR system will image the seep fields to track temporal changes and overpassing satellite acquisitions will be acquired. UAVSAR provides fine resolution, low noise radar imagery under all weather and solar conditions and is fully polarimetric, which enables evaluation of multiple methods to characterize the oil slick. The system noise floor of this instrument, considerably less than all satellite SAR instruments, enables a detailed examination of the zones of reduced backscatter caused by varying oil thickness levels. The primary satellite SAR will be C-band Sentinel-1, accompanied potentially by C-band Radarsat-2 and L-band ALOS-2. Both the UAVSAR and satellite SAR analysis will utilize the contrast ratio, defined as the normalized radar cross section (NRCS) in open water divided by the NRCS in oil-covered water. The larger the ratio, the thicker the oil. The operational algorithm for oil thickness is under development using satellite SAR data and will be staged in NOAA&amp;#8217;s SAR Ocean Product System (SAROPS) that currently produces SAR-derived wind speed and oil spill extent operationally, with the latter using the Texture-Classifying Neural Network (TCNNA) to automatically delineate oil versus non-oil covered areas. We are planning field campaigns at the natural oil seep area offshore of Santa Barbara, California, in March 2021 and during the 2022 Norwegian Clean Sea Association for Operating Companies&amp;#8217; (NOFO&amp;#8217;s) coordinated releases of oil in the North Sea. Recent field collections and analysis will be shown, as available.&lt;/p&gt;

scholarly journals The Forest Observation System, building a global reference dataset for remote sensing of forest biomass

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Dmitry Schepaschenko ◽  
Jérôme Chave ◽  
Oliver L. Phillips ◽  
Simon L. Lewis ◽  
Stuart J. Davies ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Forest Biomass ◽  
Field Measurements ◽  
Forest Degradation ◽  
Observation System ◽  
Energy Potential ◽  
Ecosystem Research ◽  
Carbon Losses ◽  
Made In

Abstract Forest biomass is an essential indicator for monitoring the Earth’s ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (AGB) is now possible with satellite remote sensing (RS). However, RS methods require extant, up-to-date, reliable, representative and comparable in situ data for calibration and validation. Here, we present the Forest Observation System (FOS) initiative, an international cooperation to establish and maintain a global in situ forest biomass database. AGB and canopy height estimates with their associated uncertainties are derived at a 0.25 ha scale from field measurements made in permanent research plots across the world’s forests. All plot estimates are geolocated and have a size that allows for direct comparison with many RS measurements. The FOS offers the potential to improve the accuracy of RS-based biomass products while developing new synergies between the RS and ground-based ecosystem research communities.

scholarly journals STUDY ON VORTEX CURRENT IN STRAIT WITH REMOTE-SENSING

1980 ◽  
Vol 1 (17) ◽  
pp. 157 ◽  
Author(s):  
Sotoaki Onishi ◽  
Tsukasa Nishimura
Keyword(s):  
Water Pollution ◽  
Remote Sensing ◽  
Boundary Conditions ◽  
Mathematical Models ◽  
Large Scale ◽  
Sea Water ◽  
Remote Sensing Data ◽  
Field Measurements ◽  
Sensing Technology ◽  
Pollution Problem

With rapid increases of industrial activity in present time, water pollution in the coastal environment has "become an urgent problem to cope with. This problem is especially serious in enclosed bays or inland seas. Hydrodynamic character of the strait connecting the inland sea to the open ocean must be understood well in order to analyse the diffusion of pollutants in the Inland sea, because its character determine boundary conditions in the mathematical models of the water pollution problem. So far however, it is seemed that the main efforts exerted by coastal engineers have concentrated mainly on the development of mathematical models, lacking satisfactory knowledge of the boundary conditions through field measurements. One reason of this state is resulted from the fact that the relating phenomena in the field are of too large scale, in general, to perform the field measurements. Connecting with this point, the authors present in this paper, that remote-sensing technology is very useful to get information of the hydrodynaniical phenomena occurring in the water body around the strait. To show the above, the authors selected as an object of the study , Naruto Strait in the Seto Inland Sea, which is world famous for the existence of rapid tidal currents and dynamic vortices. Remote-sensing data both from the airplanes and from a space satellite Landsat are analysed with the aid of theoretical considerations and hydraulic mo-del tests to disclose the behavior of the vortices of various scales and the roles of them in the sea water mixing phenomena at the strait.

scholarly journals Spatial variations of CO<sub>2</sub> fluxes in the Saguenay Fjord (Québec, Canada) and results of a water mixing model

2019 ◽  
Author(s):  
Louise Delaigue ◽  
Helmuth Thomas ◽  
Alfonso Mucci
Keyword(s):  
Surface Waters ◽  
Brackish Water ◽  
Field Measurements ◽  
Mixing Model ◽  
Isotopic Tracers ◽  
Lawrence Estuary ◽  
Relative Contribution ◽  
Saguenay Fjord ◽  
Spring Freshet ◽  
St Lawrence Estuary

Abstract. The Saguenay Fjord is a major tributary of the St. Lawrence Estuary and is strongly stratified. A 6–8 m wedge of brackish water typically overlies up to 270 m of seawater. Relative to the St. Lawrence River, the surface waters of the Saguenay Fjord are less alkaline and host higher dissolved organic carbon (DOC) concentrations. In view of the latter, surface waters of the fjord are expected to be a net source of CO2 to the atmosphere, as they partly originate from the flushing of organic-rich soil porewaters. Nonetheless, the intrusion, at the surface, of brackish water from the upper estuary with the rising tide, as well as mixing of seawater, overflowing the sill from the lower estuary, modulate the CO2 dynamics in the fjord. Using geochemical and isotopic tracers, in combination with an optimization multiparameter algorithm (OMP), we determined the relative contribution of known source-waters to the water column in the Saguenay Fjord, including waters that originate from the Lower St. Lawrence Estuary and replenish the fjord’s deep basins. These results, when combined to a conservative mixing model and compared to field measurements, serve to identify the dominant factors, other than physical mixing, such as biological activity (photosynthesis, respiration) and gas exchange at the air-water interface, that impact the water properties (e.g., pH, pCO2) of the fjord. Results indicate that the fjord’s surface waters are a net source of CO2 to the atmosphere during periods of high freshwater discharge (e.g., spring freshet) whereas they serve as a net sink of atmospheric CO2 when their practical salinity exceeds ~ 5–10.

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