Deep-sea mining may disturb the water column environment,including the surface water and deep-sea,and these disturbances should be carefully treated.Remote sensing provides high-resolution and accurate long-term obser...Deep-sea mining may disturb the water column environment,including the surface water and deep-sea,and these disturbances should be carefully treated.Remote sensing provides high-resolution and accurate long-term observations in the area around deep-sea mining.Discharge from mining ships can be identified within few days from satellite observations based on changes in reflectance.A pioneer twomonth experimental deep-sea mining cruise was conducted by The Metal Company in the eastern Pacific Ocean from September 15 to November 17,2022.A report from Greenpeace indicated incidents of surface discharge and leakage during this mining experiment.In this study,satellite observations captured a clear signal over the surface water from September 24 to October 28,indicating the location with discharged water from the mothership.The number of pixels where the potential discharged water was identified in the satellite imagery ranged from 4 to 13.The discharged water was transported by the combined effects of wind and currents,locating continuously to the downwind side of the mothership's mooring location.Remote sensing provides a timely and accurate monitoring system for tracking water discharge during deep-sea mining.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
Optical remote sensing(ORS)of reflected sun light has been used to assess oil spills in the ocean for several decades.While most applications are toward simple presence/absence detections based on the spatial contrast...Optical remote sensing(ORS)of reflected sun light has been used to assess oil spills in the ocean for several decades.While most applications are toward simple presence/absence detections based on the spatial contrast between oiled water and oil-free water,recent advances indicate the possibility of classifying oil types and quantifying oil volumes based on their spectral contrasts with oil-free water.However,a review of the current literature suggests that there is still confusion on whether this is possible and,if so,how.Here,based on the recent findings from numerical models,laboratory measurements,and applications to satellite or airborne imagery,we attempt to clarify this situation by summarizing(1)the optics behind oil spill remote sensing,and in turn,(2)how to interpret optical remote sensing imagery based on optical principles.In the end,we discuss the existing limitations and challenges as well as pathways forward to advance ORS of oil spills.展开更多
基金Supported by the National Key Research and Development Program of China(No.2023YFC2811800)the National Natural Science Foundation of China(Nos.42371380,42071387)。
文摘Deep-sea mining may disturb the water column environment,including the surface water and deep-sea,and these disturbances should be carefully treated.Remote sensing provides high-resolution and accurate long-term observations in the area around deep-sea mining.Discharge from mining ships can be identified within few days from satellite observations based on changes in reflectance.A pioneer twomonth experimental deep-sea mining cruise was conducted by The Metal Company in the eastern Pacific Ocean from September 15 to November 17,2022.A report from Greenpeace indicated incidents of surface discharge and leakage during this mining experiment.In this study,satellite observations captured a clear signal over the surface water from September 24 to October 28,indicating the location with discharged water from the mothership.The number of pixels where the potential discharged water was identified in the satellite imagery ranged from 4 to 13.The discharged water was transported by the combined effects of wind and currents,locating continuously to the downwind side of the mothership's mooring location.Remote sensing provides a timely and accurate monitoring system for tracking water discharge during deep-sea mining.
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 University of South Florida,the U.S.NOAA(NA15OAR4320064)the National Natural Science Foundation of China(No.42071387).
文摘Optical remote sensing(ORS)of reflected sun light has been used to assess oil spills in the ocean for several decades.While most applications are toward simple presence/absence detections based on the spatial contrast between oiled water and oil-free water,recent advances indicate the possibility of classifying oil types and quantifying oil volumes based on their spectral contrasts with oil-free water.However,a review of the current literature suggests that there is still confusion on whether this is possible and,if so,how.Here,based on the recent findings from numerical models,laboratory measurements,and applications to satellite or airborne imagery,we attempt to clarify this situation by summarizing(1)the optics behind oil spill remote sensing,and in turn,(2)how to interpret optical remote sensing imagery based on optical principles.In the end,we discuss the existing limitations and challenges as well as pathways forward to advance ORS of oil spills.
