This paper contrasts predicted X-band sea surface backscattering from slick-free and oil-covered sea surfaces with actual measurements acquired by the X-band satellite TerraSAR-X and COSMO-SkyMed Synthetic Aperture Ra...This paper contrasts predicted X-band sea surface backscattering from slick-free and oil-covered sea surfaces with actual measurements acquired by the X-band satellite TerraSAR-X and COSMO-SkyMed Synthetic Aperture Radar(SAR)missions.Two SAR scenes were acquired with a temporal difference of about 36 minutes,under similar met-ocean conditions,during the North Sea’s Gannet Alpha oil spill accident.The normalized radar cross section of the slick-free sea surface is predicted using the Advanced Integral Equation Model(AIEM)while the backscatter from the oiled sea surface is predicted by the AIEM augmented with the Model of Local Balance(MLB)to include the damping effect of oil slicks.Experimental results show that X-band co-polarized numerical predictions agree reasonably well with both TSX and CSK actual measurements collected over slick-free sea surfaces.When dealing with oil-covered sea surfaces,the predicted backscattering reasonably agrees with TSX measurements,while it overestimates the CSK ones.This is likely due to the different spreading conditions of the oil imaged by the two satellite missions.展开更多
Along with the rapid advance in global industrialization, oil spill events caused by offshore operations, trans- portation and accidents are increasing. Compared with ship surveys, monitoring oil spills through remote...Along with the rapid advance in global industrialization, oil spill events caused by offshore operations, trans- portation and accidents are increasing. Compared with ship surveys, monitoring oil spills through remote sensing has real-time, comprehensive, low-cost advantages, which can effectively guide cleaning and evalu- ation, and reduce the marine ecological destruction resulting from oil spills. Therefore, studying the remote sensing mechanism used to monitor marine oil spills is of great significance for ecological environmen- tal protection. This paper describes an experiment and corresponding analysis based on the above-water method, using the East China Sea coastal turbid water. The analysis shows that ＂upward short-wave＂ in ultraviolet and blue-purple bands and its displacement, along with the changing thickness, are important characteristics for distinguishing between the oil slick and the sea water, and also to differentiate oil slicks of different thicknesses. From blue to near-infrared bands, the spectrum of lube oil is flatter than that of diesel, and the diesel spectrum rises faster than the lube spectrum on the right side of the trough at 400 nm. These two features form an important basis for differentiating diesel from lube oil. These analyses will further the development of oil spill remote sensing in the East China Sea.展开更多
The dynamics of contained oil spills is investigated based on multiphase CFD (Computational Fluid Mechanics) model. The oil slick shape behind the oil boom under water current is studied. The velocity field in the oil...The dynamics of contained oil spills is investigated based on multiphase CFD (Computational Fluid Mechanics) model. The oil slick shape behind the oil boom under water current is studied. The velocity field in the oil slick is compared with the velocity field in pure water flow. The thickness of the oil slick is studied quantitatively. It is found that there is a fixed linear relationship between the oil slick relative thickness and the Froude number for different oil, different current velocity, different boom draft and different volume of oil.展开更多
The slick-water polymer adsorption damage and control measures in shale were examined using a shale pack model of the Ordovician Wufeng Formation–Silurian Longmaxi Formation in the Changning block of the Sichuan Basi...The slick-water polymer adsorption damage and control measures in shale were examined using a shale pack model of the Ordovician Wufeng Formation–Silurian Longmaxi Formation in the Changning block of the Sichuan Basin. The adsorption law of slick water under different displacement time, concentrations, p H values and temperatures of polymer were tested by traditional displacement experiment and UV-Vis spectrophotometer. The adsorption equilibrium time was 150 min, the amount of adsorption was proportional to the concentration of the polymer, and the maximum adsorption concentration was 1 800 mg/L. With the increase of p H value, the adsorption capacity decreased gradually, the adsorption capacity increased first and then decreased with the increase of temperature, and the adsorption capacity was the largest at 45 ?C. The adsorption patterns of polymers on shale were described by scanning electron microscopy and magnetic resonance imaging. It is proved that the adsorption of polymer on shale led to the destruction of the network structure of anionic polyacrylamide molecules, and the shale adsorption conformation was characterized qualitatively. Finally, according to the adsorption law and adsorption mechanism, it is proposed to reduce the adsorption quantity of polymer on shale surface by using hydrogen bond destruction agent. The effects of hydrogen bond destruction on four kinds of strong electronegative small molecules were compared, the hydrogen bond destroyer c was the best, which lowered the adsorption capacity by 5.49 mg/g and recovered permeability to 73.2%. The research results provide a reference for the optimization of construction parameters and the improvement of slickwater liquid system.展开更多
The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce...The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce water resources on the site. These unfavorable factors have brought great difficulties to the on-site mining process. Now, a nano-composite green environmental protection slick water fracturing fluid system CQFR can be quickly dissolved because of the larger specific surface area, and the small molecular size makes the damage to the reservoir less than 5%, and the average drag reduction effect can reach more than 73%. It can quickly and well dissolve and maintain performance under high salinity conditions and fracturing flowback fluids. It responds well to the complex reservoir conditions on the construction site and makes the flowback fluid recyable, which greatly reduces the consumption of water resources on the construction site and effectively improves the construction efficiency and economic benefits.展开更多
A dynamic experiment for oil dispersion into a water column was performed with a 21 m long, 0.5 m wide, and 1 m high wind-driven wave tank. At wind velocity between 6-12 m/s and with the oil slide kept constant (about...A dynamic experiment for oil dispersion into a water column was performed with a 21 m long, 0.5 m wide, and 1 m high wind-driven wave tank. At wind velocity between 6-12 m/s and with the oil slide kept constant (about 1 um), the rate of the oil content increase in the water column could be approximated from the difference between the dispersion rate (R) of the oil slick and the coagulation rate (R’) of the dispersed oil slick. Assuming the coagulation rate is directly proportional to the concentration of the water dispersed oil slick (i. e. R’ =KC),, the integral form of the dynamic model can be expressed as C=R*[1-exp(-K*t)]/K and parameters R and K can be regressed with a computer. The relative deviation of model results from the experimental data was mainly less than 10%. The oil slick dispersion rate (R) had exponential relationship with the wind velocity (V), and can be fitted with a formula R=A*(U+1)B.The fitted constant of the coagulation rate, K(0.8-3.0* 10-3 min-1) did not have significant展开更多
The purpose of this study was to investigate the characteristics of sea surface waves as they pass through oil slicks.The parameterized first-guess spectrum method(PFSM)theory-based wave retrieval algorithm was applie...The purpose of this study was to investigate the characteristics of sea surface waves as they pass through oil slicks.The parameterized first-guess spectrum method(PFSM)theory-based wave retrieval algorithm was applied to 20 images of horizontal-horizontal(HH)polarization obtained using the phased-array L-band synthetic aperture radar(SAR)(PALSAR)on the Advanced Land Observing Satellite(ALOS-1).The images were collocated with simulations from the WAVEWATCH-Ⅲ(WW3)model in a 0.1°grid using the European Centre for Medium-Range Weather Forecasts(ECMWF)reanalysis(ERA-5)winds data as the forcing field.The validation of the model-simulated significant wave height(SWH)against the measurements from the Jason-2 altimeter produced a 0.66m root mean square error(RMSE)for the SWH,with a coefficient(COR)0.74.In this sense,the WW3-simulated waves were reliable for our work.A comparison between the SAR retrieval results and the WW3 simulations was performed using the dataset for the regions without oil slicks,which produced a 0.34m RMSE for the SWH,with a COR of 0.79,which is less than a the RMSE of 0.52 m and the COR of 0.70 for the regions with oil slicks.Moreover,it was found that the SAR-derived SWHs were significantly underestimated by about 0.2m in the areas with oil slicks.This difference is probably due to the underestimation of the SAR-derived wind speeds at moderate wind speeds(i.e.,at wind speeds of greater than 5ms^(-1)).An additional analysis compared the SAR-derived wave spectra with those from the WW3 model as waves passed through the oil slicks.The interesting finding is that the wave energy at short wave lengths(about 30m)is reduced by the oil slicks,causing the movement of the dominant wave spectrum to shift to longer wave lengths(about 80 m).展开更多
Two allyldimethylalkyl quaternary ammonium salt(AQAS)monomers,N,N-dimethylallylphenylpropylammonium bromide(AQAS1)and N,N-dimethylallylnonylammonium bromide(AQAS2),were synthesized and used to prepare modified polyacr...Two allyldimethylalkyl quaternary ammonium salt(AQAS)monomers,N,N-dimethylallylphenylpropylammonium bromide(AQAS1)and N,N-dimethylallylnonylammonium bromide(AQAS2),were synthesized and used to prepare modified polyacrylamide materials.Two new drag reducers were synthesized from acrylamide(AM),sodium acrylate(Na AA)and a cationic modified monomer(AQAS1 or AQAS2)via aqueous solution polymerization,and the copolymers were named P(AM/Na AA/AQAS1)and P(AM/Na AA/AQAS2),respectively.The structures of the drag reduction agents were confirmed by IR and1H NMR spectroscopies.The molecular weight(Mw)of P(AM/Na AA/AQAS1)was 1.79×10^(6)g/mol.When the copolymer concentration was 1000 mg/L and the flow rate was 45 L/min,in fresh water the highest drag reduction rate was 75.8%,in 10,000 mg/L Na Cl solution the drag reduction rate decreased to 72.9%.The molecular weight of P(AM/Na AA/AQAS2)was 3.17×10^(6)g/mol.When the copolymer concentration was500 mg/L and the flow rate was 45 L/min,the drag reduction rate reached 75.2%,and in 10,000 mg/L Na Cl solution the drag reduction rate was 73.3%,decreased by approximately 1.9%.The drag reduction rate for partially hydrolyzed polyacrylamide(HPAM)was also investigated,and the results showed that the drag reduction rates for 500 and 1000 mg/L HPAM solutions were merely 43.2%and 49.0%in brine,respectively.Compared with HPAM,both of the above copolymers presented better drag reduction capacities.展开更多
Offshore oil slicks are significant for both the monitoring of marine spill accidents and the detection of marine oil resources.The use of remote sensing technology to detect the thickness of oil slicks is a major are...Offshore oil slicks are significant for both the monitoring of marine spill accidents and the detection of marine oil resources.The use of remote sensing technology to detect the thickness of oil slicks is a major area of research.The reflected light from oil slicks changes with the thickness of the oil.This is the theoretical basis of research on optical remote sensing of offshore oil slicks.A two-beam interference model that considers the offshore oil slick as a flat plate has been developed in this study.A quantitative remote sensing model which describes a series of processes that use oil slick thickness and reflectance as variables is established.The use of the Fresnel equation to analyze parameters in the model indicated that the key property of the quantitative relationship between the oil slick thickness and reflectance was ultimately the disappearance or extinction of the oil slick.This model has been tested and verified by data from offshore oil slick spectral response experiments.Results showed that the oil slick thickness remote sensing model can be theoretically analyzed and is efficient.The research indicated that the major cause of variations in the spectral response as a function of oil slick thickness was the different light-scattering characteristics.These characteristics can be used in remote sensing applications to identify the different types of offshore oil slicks.The theoretical interpretation of each parameter in this model led to the development of a look-up table of the model parameters which will improve the efficiency of future offshore oil slick remote sensing.展开更多
Determining oil slick thickness plays an important role in assessing oil spill volume and its environmental impacts on the ocean.In this study,we used a Hyperion image of an oil spill accident area and seawater and fr...Determining oil slick thickness plays an important role in assessing oil spill volume and its environmental impacts on the ocean.In this study,we used a Hyperion image of an oil spill accident area and seawater and fresh crude oil samples collected in the Bohai Sea of China.A well-controlled laboratory experiment was designed to simulate spectral responses to different oil slick thicknesses.Spectral resampling and normalization methods were used to reduce the differences in spectral reflectances between the experimental background seawater sample and real background seawater.Fitting the analysis with laboratory experimental data results showed a linear relationship between normalized oil slick reflectance and normalized oil slick thickness[20th band(R^(2)-0.92938,n=49,pB0.01),26th band(R^(2)=0.93806,n=49,pB0.01),29th band(R^(2)=0.93288,n=49,pB0.01)].By using these statistical models,we successfully determined the normalized oil slick thickness with the Hyperion image.Our results indicate that hyperspectral remote sensing technology is an effective method to monitor oil spills on water.The spectral ranges of visible green and red light were the optimal bands for estimating oil slick thickness in case 2 water.The high,stabilized spectral reflectance of background seawater will be helpful in oil slick thickness inversion.展开更多
The critical angle is the angle at which the contrast of oil slicks reverse their contrasts against the surrounding oil-free seawater under sunglint.Accurate determination of the critical angle can help estimate surfa...The critical angle is the angle at which the contrast of oil slicks reverse their contrasts against the surrounding oil-free seawater under sunglint.Accurate determination of the critical angle can help estimate surface roughness and refractive index of the oil slicks.Although it’s difficult to determine a certain critical angle,the potential critical angle range help to improve the estimation accuracy.In this study,the angle between the viewing direction and the direction of mirror reflection is used as an indicator for quantifying the critical angle and could be calculated from the solar/viewing geometry from observations of the Moderate Resolution Imaging Spectroradiometer(MODIS).The natural seep oil slicks in the Gulf of Mexico were first delineated using a customized segmentation approach to remove noise and apply a morphological filter.On the basis of the histograms of the brightness values of the delineated oil slicks,the potential range of the critical angle was determined,and then an optimal critical angle between oil slicks and seawater was then determined from statistical and regression analyses in this range.This critical angle corresponds to the best fitting between the modeled and observed surface roughness of seep oil slicks and seawater.展开更多
Based on particle approach and tidal flow model this article studies the behavior of the oil slick on the water surface in the Huangpu River, a tidal waterway in Shanghai. In order to track the oil slick motion, a two...Based on particle approach and tidal flow model this article studies the behavior of the oil slick on the water surface in the Huangpu River, a tidal waterway in Shanghai. In order to track the oil slick motion, a two-dimensional oil trajectory model is used. The dynamical properties of spilled oil characterized by advection, oil spreading and turbulent diffusion are considered in the model. The simulation results consistent with the flume experimental data show that the model is applicable. Both simulation and experiment illustrate that the tidal flow has a great influence on the oil slick motion. The calculated results can be used as a reference for the response to oil spill accidents in rivers.展开更多
基金supported by the National Key R&D Program of China[Grant number 2021YFB3901300]the ESA-NRSCC Dragon-5 cooperation project[ID 57979]+1 种基金the Agenzia Spaziale Italiana under the APPLICAVEMARS project[ASI contract n.2021-4-U.0]the China Scholarship Council.
文摘This paper contrasts predicted X-band sea surface backscattering from slick-free and oil-covered sea surfaces with actual measurements acquired by the X-band satellite TerraSAR-X and COSMO-SkyMed Synthetic Aperture Radar(SAR)missions.Two SAR scenes were acquired with a temporal difference of about 36 minutes,under similar met-ocean conditions,during the North Sea’s Gannet Alpha oil spill accident.The normalized radar cross section of the slick-free sea surface is predicted using the Advanced Integral Equation Model(AIEM)while the backscatter from the oiled sea surface is predicted by the AIEM augmented with the Model of Local Balance(MLB)to include the damping effect of oil slicks.Experimental results show that X-band co-polarized numerical predictions agree reasonably well with both TSX and CSK actual measurements collected over slick-free sea surfaces.When dealing with oil-covered sea surfaces,the predicted backscattering reasonably agrees with TSX measurements,while it overestimates the CSK ones.This is likely due to the different spreading conditions of the oil imaged by the two satellite missions.
基金scientific research fund of the National Key Technology Research and Development Program of China under contact No.2012BAH32B01Second Institute of Oceanography,State Oceanic Administration(SOA)under contact No.JG1016Public science and technology research funds project of ocean under contact No.200805028
文摘Along with the rapid advance in global industrialization, oil spill events caused by offshore operations, trans- portation and accidents are increasing. Compared with ship surveys, monitoring oil spills through remote sensing has real-time, comprehensive, low-cost advantages, which can effectively guide cleaning and evalu- ation, and reduce the marine ecological destruction resulting from oil spills. Therefore, studying the remote sensing mechanism used to monitor marine oil spills is of great significance for ecological environmen- tal protection. This paper describes an experiment and corresponding analysis based on the above-water method, using the East China Sea coastal turbid water. The analysis shows that ＂upward short-wave＂ in ultraviolet and blue-purple bands and its displacement, along with the changing thickness, are important characteristics for distinguishing between the oil slick and the sea water, and also to differentiate oil slicks of different thicknesses. From blue to near-infrared bands, the spectrum of lube oil is flatter than that of diesel, and the diesel spectrum rises faster than the lube spectrum on the right side of the trough at 400 nm. These two features form an important basis for differentiating diesel from lube oil. These analyses will further the development of oil spill remote sensing in the East China Sea.
文摘The dynamics of contained oil spills is investigated based on multiphase CFD (Computational Fluid Mechanics) model. The oil slick shape behind the oil boom under water current is studied. The velocity field in the oil slick is compared with the velocity field in pure water flow. The thickness of the oil slick is studied quantitatively. It is found that there is a fixed linear relationship between the oil slick relative thickness and the Froude number for different oil, different current velocity, different boom draft and different volume of oil.
基金Supported by the China National Science and Technology Major Project(2016ZX05021,2016ZX05023)
文摘The slick-water polymer adsorption damage and control measures in shale were examined using a shale pack model of the Ordovician Wufeng Formation–Silurian Longmaxi Formation in the Changning block of the Sichuan Basin. The adsorption law of slick water under different displacement time, concentrations, p H values and temperatures of polymer were tested by traditional displacement experiment and UV-Vis spectrophotometer. The adsorption equilibrium time was 150 min, the amount of adsorption was proportional to the concentration of the polymer, and the maximum adsorption concentration was 1 800 mg/L. With the increase of p H value, the adsorption capacity decreased gradually, the adsorption capacity increased first and then decreased with the increase of temperature, and the adsorption capacity was the largest at 45 ?C. The adsorption patterns of polymers on shale were described by scanning electron microscopy and magnetic resonance imaging. It is proved that the adsorption of polymer on shale led to the destruction of the network structure of anionic polyacrylamide molecules, and the shale adsorption conformation was characterized qualitatively. Finally, according to the adsorption law and adsorption mechanism, it is proposed to reduce the adsorption quantity of polymer on shale surface by using hydrogen bond destruction agent. The effects of hydrogen bond destruction on four kinds of strong electronegative small molecules were compared, the hydrogen bond destroyer c was the best, which lowered the adsorption capacity by 5.49 mg/g and recovered permeability to 73.2%. The research results provide a reference for the optimization of construction parameters and the improvement of slickwater liquid system.
文摘The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce water resources on the site. These unfavorable factors have brought great difficulties to the on-site mining process. Now, a nano-composite green environmental protection slick water fracturing fluid system CQFR can be quickly dissolved because of the larger specific surface area, and the small molecular size makes the damage to the reservoir less than 5%, and the average drag reduction effect can reach more than 73%. It can quickly and well dissolve and maintain performance under high salinity conditions and fracturing flowback fluids. It responds well to the complex reservoir conditions on the construction site and makes the flowback fluid recyable, which greatly reduces the consumption of water resources on the construction site and effectively improves the construction efficiency and economic benefits.
文摘A dynamic experiment for oil dispersion into a water column was performed with a 21 m long, 0.5 m wide, and 1 m high wind-driven wave tank. At wind velocity between 6-12 m/s and with the oil slide kept constant (about 1 um), the rate of the oil content increase in the water column could be approximated from the difference between the dispersion rate (R) of the oil slick and the coagulation rate (R’) of the dispersed oil slick. Assuming the coagulation rate is directly proportional to the concentration of the water dispersed oil slick (i. e. R’ =KC),, the integral form of the dynamic model can be expressed as C=R*[1-exp(-K*t)]/K and parameters R and K can be regressed with a computer. The relative deviation of model results from the experimental data was mainly less than 10%. The oil slick dispersion rate (R) had exponential relationship with the wind velocity (V), and can be fitted with a formula R=A*(U+1)B.The fitted constant of the coagulation rate, K(0.8-3.0* 10-3 min-1) did not have significant
基金supported by the National Natural Science Foundation of China(Nos.41906152 and 42076238).
文摘The purpose of this study was to investigate the characteristics of sea surface waves as they pass through oil slicks.The parameterized first-guess spectrum method(PFSM)theory-based wave retrieval algorithm was applied to 20 images of horizontal-horizontal(HH)polarization obtained using the phased-array L-band synthetic aperture radar(SAR)(PALSAR)on the Advanced Land Observing Satellite(ALOS-1).The images were collocated with simulations from the WAVEWATCH-Ⅲ(WW3)model in a 0.1°grid using the European Centre for Medium-Range Weather Forecasts(ECMWF)reanalysis(ERA-5)winds data as the forcing field.The validation of the model-simulated significant wave height(SWH)against the measurements from the Jason-2 altimeter produced a 0.66m root mean square error(RMSE)for the SWH,with a coefficient(COR)0.74.In this sense,the WW3-simulated waves were reliable for our work.A comparison between the SAR retrieval results and the WW3 simulations was performed using the dataset for the regions without oil slicks,which produced a 0.34m RMSE for the SWH,with a COR of 0.79,which is less than a the RMSE of 0.52 m and the COR of 0.70 for the regions with oil slicks.Moreover,it was found that the SAR-derived SWHs were significantly underestimated by about 0.2m in the areas with oil slicks.This difference is probably due to the underestimation of the SAR-derived wind speeds at moderate wind speeds(i.e.,at wind speeds of greater than 5ms^(-1)).An additional analysis compared the SAR-derived wave spectra with those from the WW3 model as waves passed through the oil slicks.The interesting finding is that the wave energy at short wave lengths(about 30m)is reduced by the oil slicks,causing the movement of the dominant wave spectrum to shift to longer wave lengths(about 80 m).
基金supported by the National Natural Science Foundation of China(Project Nos.51774062 and 52274032)Scientific and Technological Key Research Program of Chongqing Municipal Education Commission(KJZD-K201901502)+1 种基金General Project of Chongqing Natural Science Foundation(CSTB2022NSCQMSX0349)Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202313101)。
文摘Two allyldimethylalkyl quaternary ammonium salt(AQAS)monomers,N,N-dimethylallylphenylpropylammonium bromide(AQAS1)and N,N-dimethylallylnonylammonium bromide(AQAS2),were synthesized and used to prepare modified polyacrylamide materials.Two new drag reducers were synthesized from acrylamide(AM),sodium acrylate(Na AA)and a cationic modified monomer(AQAS1 or AQAS2)via aqueous solution polymerization,and the copolymers were named P(AM/Na AA/AQAS1)and P(AM/Na AA/AQAS2),respectively.The structures of the drag reduction agents were confirmed by IR and1H NMR spectroscopies.The molecular weight(Mw)of P(AM/Na AA/AQAS1)was 1.79×10^(6)g/mol.When the copolymer concentration was 1000 mg/L and the flow rate was 45 L/min,in fresh water the highest drag reduction rate was 75.8%,in 10,000 mg/L Na Cl solution the drag reduction rate decreased to 72.9%.The molecular weight of P(AM/Na AA/AQAS2)was 3.17×10^(6)g/mol.When the copolymer concentration was500 mg/L and the flow rate was 45 L/min,the drag reduction rate reached 75.2%,and in 10,000 mg/L Na Cl solution the drag reduction rate was 73.3%,decreased by approximately 1.9%.The drag reduction rate for partially hydrolyzed polyacrylamide(HPAM)was also investigated,and the results showed that the drag reduction rates for 500 and 1000 mg/L HPAM solutions were merely 43.2%and 49.0%in brine,respectively.Compared with HPAM,both of the above copolymers presented better drag reduction capacities.
基金supported by National Natural Science Foundation of China (Grant Nos. 40971186 and 41001196 )the Open Research Fund of Key Laboratory of Digital Earth,Center for Earth Observation and Digital Earth,Chinese Academy of Sciences (Grant No. 2010LDE007)
文摘Offshore oil slicks are significant for both the monitoring of marine spill accidents and the detection of marine oil resources.The use of remote sensing technology to detect the thickness of oil slicks is a major area of research.The reflected light from oil slicks changes with the thickness of the oil.This is the theoretical basis of research on optical remote sensing of offshore oil slicks.A two-beam interference model that considers the offshore oil slick as a flat plate has been developed in this study.A quantitative remote sensing model which describes a series of processes that use oil slick thickness and reflectance as variables is established.The use of the Fresnel equation to analyze parameters in the model indicated that the key property of the quantitative relationship between the oil slick thickness and reflectance was ultimately the disappearance or extinction of the oil slick.This model has been tested and verified by data from offshore oil slick spectral response experiments.Results showed that the oil slick thickness remote sensing model can be theoretically analyzed and is efficient.The research indicated that the major cause of variations in the spectral response as a function of oil slick thickness was the different light-scattering characteristics.These characteristics can be used in remote sensing applications to identify the different types of offshore oil slicks.The theoretical interpretation of each parameter in this model led to the development of a look-up table of the model parameters which will improve the efficiency of future offshore oil slick remote sensing.
基金supported by National Natural Science Foundation of China(Grant No.41001196)the Open Research Fund of Key Laboratory of Marine Spill Oil Identification and Damage Assessment Technology,SOA(Grant No.201212)the Open Research Fund of Key Laboratory of Digital Earth,Center for Earth Observation and Digital Earth,Chinese Academy of Sciences(Grant No.2010LDE007).
文摘Determining oil slick thickness plays an important role in assessing oil spill volume and its environmental impacts on the ocean.In this study,we used a Hyperion image of an oil spill accident area and seawater and fresh crude oil samples collected in the Bohai Sea of China.A well-controlled laboratory experiment was designed to simulate spectral responses to different oil slick thicknesses.Spectral resampling and normalization methods were used to reduce the differences in spectral reflectances between the experimental background seawater sample and real background seawater.Fitting the analysis with laboratory experimental data results showed a linear relationship between normalized oil slick reflectance and normalized oil slick thickness[20th band(R^(2)-0.92938,n=49,pB0.01),26th band(R^(2)=0.93806,n=49,pB0.01),29th band(R^(2)=0.93288,n=49,pB0.01)].By using these statistical models,we successfully determined the normalized oil slick thickness with the Hyperion image.Our results indicate that hyperspectral remote sensing technology is an effective method to monitor oil spills on water.The spectral ranges of visible green and red light were the optimal bands for estimating oil slick thickness in case 2 water.The high,stabilized spectral reflectance of background seawater will be helpful in oil slick thickness inversion.
基金Natural Science Foundation of Jiangsu Province[Grant no.BK20160023] National Natural Science Foundation of China[Grant Nos.41771376,41371014,61675099]the National Key Research and Development Program of China[Grant no.2016YFC1400901].
文摘The critical angle is the angle at which the contrast of oil slicks reverse their contrasts against the surrounding oil-free seawater under sunglint.Accurate determination of the critical angle can help estimate surface roughness and refractive index of the oil slicks.Although it’s difficult to determine a certain critical angle,the potential critical angle range help to improve the estimation accuracy.In this study,the angle between the viewing direction and the direction of mirror reflection is used as an indicator for quantifying the critical angle and could be calculated from the solar/viewing geometry from observations of the Moderate Resolution Imaging Spectroradiometer(MODIS).The natural seep oil slicks in the Gulf of Mexico were first delineated using a customized segmentation approach to remove noise and apply a morphological filter.On the basis of the histograms of the brightness values of the delineated oil slicks,the potential range of the critical angle was determined,and then an optimal critical angle between oil slicks and seawater was then determined from statistical and regression analyses in this range.This critical angle corresponds to the best fitting between the modeled and observed surface roughness of seep oil slicks and seawater.
基金supported by the National Natural Science Foundation of China (Grant No.10972134)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No.20050280008)
文摘Based on particle approach and tidal flow model this article studies the behavior of the oil slick on the water surface in the Huangpu River, a tidal waterway in Shanghai. In order to track the oil slick motion, a two-dimensional oil trajectory model is used. The dynamical properties of spilled oil characterized by advection, oil spreading and turbulent diffusion are considered in the model. The simulation results consistent with the flume experimental data show that the model is applicable. Both simulation and experiment illustrate that the tidal flow has a great influence on the oil slick motion. The calculated results can be used as a reference for the response to oil spill accidents in rivers.
