CN108664449B - Method and device for estimating oil-spilling oil-water mixing rate, storage medium and computing equipment - Google Patents
Method and device for estimating oil-spilling oil-water mixing rate, storage medium and computing equipment Download PDFInfo
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Abstract
The invention discloses a method and a device for estimating the oil-water mixing rate of oil spilling, a storage medium and computing equipment. The disclosed method comprises: calculating a covariance matrix C corresponding to an oil area pixel based on CPSAR observation data of the oil areaCPObserved ratio of major diagonal elements of
According to the actual incidence angle value theta corresponding to the oil area pixel and the observation ratio corresponding to the oil area pixel
The oil-water mixing ratio lookup table is searched to obtain the estimated value of the oil-water mixing ratio of the oil film corresponding to the oil area pixel
The disclosed method can accurately estimate the sea surface oil spill oil-water mixing ratio by using the remote sensing observation data of the CPSAR.
Description
Technical Field
The invention relates to the field of marine environment three-dimensional monitoring, in particular to a method and a device for estimating the oil-water mixing rate of oil spilling, a storage medium and computing equipment.
Background
In the remote sensing monitoring and evaluation of offshore oil, sea surface oil spill is an important object for remote sensing detection, and a certain research is carried out in the fields of multispectral, thermal infrared, radar and the like. Because the ocean background is complex, the sea surface is influenced by the atmosphere, and the water body has the scattering and absorption effects on electromagnetic waves, the sea surface oil film remote sensing information is expressed as weak information; the sea surface spilled oil is characterized by uncertain remote sensing images according to different sources, composition types, oil film thickness, emulsification degree and existence time; the factors have certain restrictions on the extraction of the remote sensing information of the oil film on the sea surface.
At present, the detection of sea surface oil spill pollution in China has achieved a few achievements, remote sensing detection, classification and quantification aiming at sea surface oil spill are always key, difficult and hot points in the field of ocean resource and environment remote sensing research, and no effective method exists so far for realizing real-time, dynamic, quantitative and rapid measurement of sea surface oil spill oil film quantity. The oil-water mixing rate is a key parameter for estimating the oil spilling amount, is an important index necessary for dealing with oil spilling accidents, particularly for making oil spilling control measures and evaluating the performance of a dispersant, and has important significance for accurately estimating the oil spilling amount and quickly responding to the oil spilling accidents.
Compact Polarization Synthetic Aperture Radar (CPSAR) is a new type of Synthetic Aperture Radar (SAR). Compared with an optical sensor, the CPSAR is an active microwave sensor, microwave energy penetrates through darkness, cloud layers, dust and fog, and has the advantages of observation all day long and all day long, high resolution, less interference and the like. The CPSAR can be carried on satellites, airplanes and ships, is flexible to use, is relatively advanced, has the advantages of wide cradling range and short revisit period, and is more suitable for large-area monitoring on the sea. Currently, RISAT-1 in India (emission at 26/4/2012) and ALOS-2 in Japan (emission at 24/5/2014) carry the new sensor. Meanwhile, the RADARSAT Constellation Session (RCM) in Canada is planned to be launched in 2018, and the swath of the novel sensor can reach 350 km. Therefore, the research on the sea surface oil spill oil-water mixing rate of the CPSAR needs to be carried out urgently.
In summary, a new technical solution for accurately estimating the oil-water mixing rate of the sea surface spilled oil by combining with the observed data of the CPSAR needs to be provided.
Disclosure of Invention
The method for estimating the sea surface oil spill oil-water mixing rate comprises the following steps:
calculating a covariance matrix C corresponding to an oil area pixel based on CPSAR observation data of the oil areaCPObserved ratio of major diagonal elements of
According to the actual incidence angle value theta corresponding to the oil area pixel and the observation ratio corresponding to the oil area pixel
The oil-water mixing ratio lookup table is searched to obtain the estimated value of the oil-water mixing ratio of the oil film corresponding to the oil area pixel
Wherein, the covariance matrix CCPThe formula of (1) is as follows:
wherein,
representing approximately equal to, representing the conjugate transpose,<·>representing the ensemble averaging of a number of adjacent pixels for speckle noise removal, SpqDenotes the complex scattering coefficient, SpqSubscripts p, q in (1) are polarization modes of electromagnetic waves transmitted and received by the CPSAR, HH represents horizontal polarization, VV represents vertical polarization, HV and VH represent cross polarization,
shows the Normalized Radar backscattering Cross Section NRCS (Normalized Radar Cross Section) in the strained-Bragg scattering mode) The formula (c) of (a),
the formula for NRCS is as follows:
wherein k isrThe radar wavenumber representing CPSAR, W (-) represents the wave spectral function of the Bragg wavenumber used to describe the roughness of the sea surface, the reflection function ΓpqThe formula of (1) is as follows:
wherein,
wherein,
where ψ and ζ are the azimuth and distance-to-sea surface inclination angles, θ, respectivelyiIs a local incidence angle value, w, corresponding to an actual incidence angle value theta corresponding to the oil region pixel0Is the oil-water mixing ratio, w0The value thereof is 0 or more and 1 or less,
is the dielectric constant of the oil and is,
is the dielectric constant of water,. epsilonrThe actual dielectric constant of the oil film corresponding to the oil area pixel.
The method for estimating the oil-water mixing ratio further comprises the following steps:
based on CPSAR observation data of the water area near the oil area, calculating a covariance matrix C corresponding to the water area pixel near the oil area pixelCPObserved ratio of major diagonal elements of
Dielectric constant of water based on NRCS formula
Observation ratio
And the ratio of the theoretical calculation
Approximately equal preconditions, and the pixel local angle of incidence value θiThe following angular relationships between the angle of incidence value θ, the azimuth and the angle of inclination of the distance to the ocean surface (ψ, ζ):
θi＝cos-1[cos(θ+ψ)cosζ]
calculating the estimated value of the surface inclination angle of the ocean in the water area
Wherein the estimated value of the surface inclination angle of the ocean in the water area
The following relation is satisfied:
based on the estimated values of the inclination angle (psi, zeta) of the ocean surface of the oil region and the inclination angle of the ocean surface of the water region
The same precondition and angle relation formula are used for calculating the local incidence angle value theta of the oil area pixels corresponding to all the different pixel incidence angle values theta with the angle interval of the first specified valueiAll different oil-water mixing ratios w with numerical intervals of a second specified value0Corresponding different oil-water mixed dielectric constants epsilonrLocal incidence angle value theta of pixels in different oil areasiAnd dielectric constant epsilon of different oil-water mixturesrCorresponding different oil-water mixture alphaHHAnd alphaVVBased on the inclination angle (psi, zeta) of the ocean surface in the oil region, different incidence angle values theta, and local incidence angle values theta of different oil region pixelsiAlpha of different oil-water mixtureHHAnd alphaVVCalculating different oil-water mixtures gammaHH、ΓVVAnd ΓHVAnd different oil-water mixing theory calculated ratios
And constructing an oil-water mixing rate lookup table.
According to the method for estimating the oil-water mixing rate, the covariance matrix C corresponding to the pixel of the oil area is calculatedCPObserved ratio of major diagonal elements of
Then, the observation ratio of each pixel with the signal-to-noise ratio greater than the preset threshold value in one oil area pixel and the adjacent pixels to be calculated is calculated
The average value of the obtained values is used as a new observation ratio value corresponding to the oil area pixel to be calculated
According to the method for estimating the oil-water mixing ratio of the present invention, the first specified value is 1 degree or less, and the second specified value is 0.1 or less.
The device for estimating the sea surface oil spill oil-water mixing rate comprises:
an observation ratio calculation module used for calculating a covariance matrix C corresponding to the oil area pixel based on the CPSAR observation data of the oil areaCPObserved ratio of major diagonal elements of
An oil-water mixing rate estimation module for estimating the oil-water mixing rate according to the actual incidence angle value theta corresponding to the oil area pixel and the observation ratio corresponding to the oil area pixel
The oil-water mixing ratio lookup table is searched to obtain the estimated value of the oil-water mixing ratio of the oil film corresponding to the oil area pixel
Wherein, the covariance matrix CCPThe formula of (1) is as follows:
wherein,
representing approximately equal to, representing the conjugate transpose,<·>representing the ensemble averaging of a number of adjacent pixels for speckle noise removal, SpqDenotes the complex scattering coefficient, SpqSubscripts p, q in (1) are polarization modes of electromagnetic waves transmitted and received by the CPSAR, HH represents horizontal polarization, VV represents vertical polarization, HV and VH represent cross polarization,
a formula representing the normalized radar backscattering cross section NRCS in the tilted-Bragg scattering mode,
the formula for NRCS is as follows:
wherein k isrThe radar wavenumber representing CPSAR, W (-) represents the wave spectral function of the Bragg wavenumber used to describe the roughness of the sea surface, the reflection function ΓpqThe formula of (1) is as follows:
wherein,
wherein,
where ψ and ζ are the azimuth and distance-to-sea surface inclination angles, θ, respectivelyiIs a local incidence angle value, w, corresponding to an actual incidence angle value theta corresponding to the oil region pixel0The oil-water mixing ratio，w0The value thereof is 0 or more and 1 or less,
is the dielectric constant of the oil and is,
is the dielectric constant of water,. epsilonrThe actual dielectric constant of the oil film corresponding to the oil area pixel.
The estimation device of the oil-water mixing ratio, the observation ratio calculation module and the like are also used for calculating a covariance matrix C corresponding to the water area pixel nearby the oil area pixel based on the CPSAR observation data of the water area nearby the oil areaCPObserved ratio of major diagonal elements of
The estimation device further includes:
ocean surface inclination angle estimation module for water dielectric constant based on NRCS formula
Observation ratio
And the ratio of the theoretical calculation
Approximately equal preconditions, and the pixel local angle of incidence value θiThe following angular relationships between the angle of incidence value θ, the azimuth and the angle of inclination of the distance to the ocean surface (ψ, ζ):
θi＝cos-1[cos(θ+ψ)cosζ]
calculating the estimated value of the surface inclination angle of the ocean in the water area
Wherein the estimated value of the surface inclination angle of the ocean in the water area
The following relationship is satisfied:
an oil-water mixing ratio lookup table construction module used for estimating the marine surface inclination angle (psi, zeta) of the oil area and the marine surface inclination angle of the water area
The same precondition and angle relation formula are used for calculating the local incidence angle value theta of the oil area pixels corresponding to all the different pixel incidence angle values theta with the angle interval of the first specified valueiAll different oil-water mixing ratios w with numerical intervals of a second specified value0Corresponding different oil-water mixed dielectric constants epsilonrLocal incidence angle value theta of pixels in different oil areasiAnd dielectric constant epsilon of different oil-water mixturesrCorresponding different oil-water mixture alphaHHAnd alphaVVBased on the inclination angle (psi, zeta) of the ocean surface in the oil region, different incidence angle values theta, and local incidence angle values theta of different oil region pixelsiAlpha of different oil-water mixtureHHAnd alphaVVCalculating different oil-water mixtures gammaHH、ΓVVAnd ΓHVAnd different oil-water mixing theory calculated ratios
And constructing an oil-water mixing rate lookup table.
According to the estimation device of the oil-water mixing rate, the observation ratio calculation module calculates the covariance matrix C corresponding to the pixel of the oil areaCPObserved ratio of major diagonal elements of
Then, the observation ratio of each pixel with the signal-to-noise ratio greater than the preset threshold value in one oil area pixel and the adjacent pixels to be calculated is calculated
The average value of the obtained values is used as a new observation ratio value corresponding to the oil area pixel to be calculated
According to the oil-water mixing ratio estimation device of the present invention, the first specified value is 1 degree or less, and the second specified value is 0.1 or less.
According to the computer-readable storage medium of the invention, a computer program is stored on the storage medium, which program, when being executed by a processor, carries out the steps of the method as described above.
The computing device according to the invention comprises a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the method described above when executing the program.
According to the technical scheme of the invention, the oil-water mixing rate of the sea surface spilled oil can be accurately estimated by using the remote sensing observation data of the (satellite-borne, airborne and shipborne) CPSAR.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. In the drawings, like reference numerals are used to indicate like elements. The drawings in the following description are directed to some, but not all embodiments of the invention. For a person skilled in the art, other figures can be derived from these figures without inventive effort.
Fig. 1 schematically shows a flow chart of a method for estimating the sea surface spill oil-water mixing ratio according to the invention.
Fig. 2 schematically shows a block diagram of an apparatus for estimating the sea surface spill oil-water mixing ratio according to the present invention.
Fig. 3 is a schematic diagram of a radar near incident angle and a radar far incident angle according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.
The general design idea of the technical scheme of the invention is as follows: the backscattering of rough sea surfaces is dominated by Bragg scattering when radar angle of incidence values are 20 to 70 degrees. Based on the clipped-Bragg scattering mode, the sea surface Normalized Radar backscattering Cross Section (NRCS) is a function of the angle of incidence, the dielectric properties of the seawater, and the sea spectrum describing the sea surface roughness. However, the ratio of the elements of the CPSAR covariance matrix is only related to the incident angle and the dielectric constant, and is not related to the wave spectrum or the roughness of the sea surface. Therefore, the dielectric properties of the observed object can be obtained by using the ratio of the CPSAR covariance matrix elements obtained based on the telemetric observation data. For example, the oil film oil-water mixing ratio can be obtained based on CPSAR remote sensing observation data and by adopting an optimization algorithm and establishing a lookup table. The following describes a specific embodiment of the present invention in detail with reference to the accompanying drawings.
Fig. 1 schematically shows a flow chart of a method for estimating the sea surface spill oil-water mixing ratio according to the invention.
As shown in the solid line box of fig. 1, the method for estimating the sea surface oil-water mixture ratio according to the present invention includes:
step S102: calculating a covariance matrix C corresponding to an oil area pixel based on CPSAR observation data of the oil areaCPObserved ratio of major diagonal elements of
Step S104: root of herbaceous plantAccording to the actual incidence angle value theta corresponding to the oil area pixel and the observation ratio corresponding to the oil area pixel
The oil-water mixing ratio lookup table is searched to obtain the estimated value of the oil-water mixing ratio of the oil film corresponding to the oil area pixel
Wherein, the covariance matrix CCPThe formula of (1) is as follows:
wherein,
representing approximately equal to, representing the conjugate transpose,<·>representing the ensemble averaging of a number of adjacent pixels for speckle noise removal, SpqDenotes the complex scattering coefficient, SpqSubscripts p, q in (1) are polarization modes of electromagnetic waves transmitted and received by the CPSAR, HH represents horizontal polarization, VV represents vertical polarization, HV and VH represent cross polarization,
and (3) a formula for expressing the normalized radar backscattering cross section NRCS in the tilted-Bragg scattering mode.
The formula of NRCS in the prior art is as follows:
wherein k isrRepresenting the radar wavenumber, W (-) representing the wave spectrum function of the Bragg wavenumber used to describe the roughness of the sea surface, the reflection function ΓpqThe formula of (1) is as follows:
wherein,
wherein,
where ψ and ζ are the azimuth and distance-to-sea surface inclination angles, θ, respectivelyiIs a local incidence angle value, w, corresponding to an actual incidence angle value theta corresponding to the oil region pixel0The oil-water mixing ratio is 0 to 1 inclusive,
is the dielectric constant of the oil and is,
is the dielectric constant of water,. epsilonrThe actual dielectric constant of the oil film corresponding to the oil area pixel.
For example, the oil-water mixing ratio w0A value of 0 means that the mixture is completely water, and the mixing ratio w of oil and water0A value of 1 represents completely oil.
For example, the range of the actual angle of incidence value θ corresponding to the oil region pixel is the range of radar angle of incidence values (20 degrees to 70 degrees) as described above. In the calculation, the actual angle of incidence value θ can be obtained from the imaging geometry.
For example, the covariance matrix CCPIs a covariance matrix of a CPSAR (i.e., a CPSAR in a combined mode) of a circular polarization transmission and linear polarization reception type used in the prior art, and a scattering vector thereof can be represented by a quadrupolar scattering vector of linear polarization transmission and linear polarization reception. Reference is made to the "Hybrid-polarity SAR architecture" (stage 45(11), page 3397-3404) published by R.K. Raney in IEEE Transactions on Geoscience and Remote Sensing, 2007. CCPThe elements in the matrix are inclined to the angle of incidence value theta, the long-wave tilt angle (i.e., the azimuth and distance to the ocean surface tilt angle psi, zeta)), the dielectric constant epsilonrRelated to the wave spectrum or roughness of the sea surface (i.e., W (-)); but C isCPThe ratio of diagonal elements in the matrix is only related to the incidence angle values θ, the long-wave tilt angles (i.e., azimuth and distance-to-sea surface tilt angles (ψ, ζ)), the dielectric constant εrThis is relevant regardless of the wave spectrum or roughness of the sea surface (i.e., W (-).
Alternatively, as shown in a dashed box of fig. 1, the method for estimating an oil-water mixing ratio according to the present invention further includes:
step S106: based on CPSAR observation data of the water area near the oil area, calculating a covariance matrix C corresponding to the water area pixel near the oil area pixelCPObserved ratio of major diagonal elements of
Step S108: dielectric constant of water based on NRCS formula
Observation ratio
And the ratio of the theoretical calculation
Approximately equal preconditions, and the pixel local angle of incidence value θiThe following angular relationships between the angle of incidence value θ, the azimuth and the angle of inclination of the distance to the ocean surface (ψ, ζ):
θi＝cos-1[cos(θ+ψ)cosζ]
calculating the estimated value of the surface inclination angle of the ocean in the water area
Wherein the estimated value of the surface inclination angle of the ocean in the water area
The following relation is satisfied:
step S110: based on the estimated values of the inclination angle (psi, zeta) of the ocean surface of the oil region and the inclination angle of the ocean surface of the water region
The same precondition and angle relation formula are used for calculating the local incidence angle value theta of the oil area pixels corresponding to all the different pixel incidence angle values theta with the angle interval of the first specified valueiAll different oil-water mixing ratios w with numerical intervals of a second specified value0Corresponding different oil-water mixed dielectric constants epsilonrLocal incidence angle value theta of pixels in different oil areasiAnd dielectric constant epsilon of different oil-water mixturesrCorresponding different oil-water mixture alphaHHAnd alphaVVBased on the inclination angle (psi, zeta) of the ocean surface in the oil region, different incidence angle values theta, and local incidence angle values theta of different oil region pixelsiAlpha of different oil-water mixtureHHAnd alphaVVCalculating different oil-water mixtures gammaHH、ΓVVAnd ΓHVAnd different oil-water mixing theory calculated ratios
And constructing an oil-water mixing rate lookup table.
For example, in step S108 described above, the angle of incidence values θ (θ) for all the values of angles of incidence that satisfy the condition (e.g., spaced by the first specified value, as described above)1<θ<θ2) For example, unconstrained non-linear optimization method can be used to minimize the cost function F (ψ, ζ) (i.e., min { F (ψ, ζ) }) to finally obtain the estimated value of the sea surface inclination angle of the water area
Wherein, theta1And theta2The radar near incidence angle and the radar far incidence angle, theta, respectively, as shown in FIG. 31And theta2Are all equal to or greater than 20 degrees and equal to or less than 70 degrees, and H in fig. 3 represents the vertical height of the satellite.
In step S110, the inclination angle (ψ, ζ) of the ocean surface in the oil zone and the estimated value of the inclination angle of the ocean surface in the water zone
The same preconditions are obtained according to the following principles:
the wave spectrum due to long waves is determined by the sea surface inclination (ψ, ζ). The occurrence of oil spill attenuates only the short wave of the sea surface and has little effect on the sea surface inclination determined by the long wave, i.e. the sea surface inclination angles (ψ, ζ) of the adjacent water and oil regions are uniform.
According to the method for estimating the oil-water mixing ratio of the present invention, in step S102, the observation ratio of each pixel having a signal-to-noise ratio greater than a predetermined threshold value in one oil region pixel to be calculated and its neighboring pixels is calculated
The average value of the obtained values is used as a new observation ratio value corresponding to the oil area pixel to be calculated
For example, for each pixel in the image, a window is taken centered on it, and the C within the window that satisfies the condition (above the radar noise level (NESZ) and for non-ship targets and non-oil platform targets) is foundcp11、Ccp22Average (hfilt, vfilt) and ratio of pixels
(rfilt)。
If the difference between vfilt and NESZ is greater than a predetermined threshold (e.g., 6dB), then the following is done:
for a pixel with an incidence angle theta, a polarization ratio with the pixel is searched in a lookup table
(i.e., rfilt) the closest entry (as shown in Table 1 below), i.e., such that
Established table entry
W of the table entry0Namely the oil-water mixing rate estimated value of the oil spill at the position of the ocean surface corresponding to the pixel, namely the oil film
For example, if the incident angle θ of the pixel p1 is 15 degrees, an element with the incident angle θ of 15 degrees and the polarization ratio closest to p1 needs to be found in the lookup table, and the oil-water mixing ratio corresponding to the element is an estimated value of the oil-water mixing ratio of the oil film at the sea surface position corresponding to the pixel
According to the method for estimating the oil-water mixing ratio of the present invention, the first specified value (i.e., the angular interval) is 1 or less, and the second specified value isConstant value (i.e., w)0Interval of values) of 0.1 or less.
For example, an example format of the oil-water mixing ratio look-up table is shown in table 1.
TABLE 1 oil-water mixing ratio lookup table with first specified value of 1 degree and second specified value of 0.001
Fig. 2 schematically shows a block diagram of an apparatus 200 for estimating the sea surface spill oil-water mixing ratio according to the present invention.
As shown in the solid line box of fig. 2, the estimation apparatus 200 for sea surface oil spill water mixing ratio includes:
an observation ratio calculation module 201, configured to calculate a covariance matrix C corresponding to an oil region pixel based on the CPSAR observation data of the oil regionCPObserved ratio of major diagonal elements of
An oil-water mixing ratio estimation module 203, configured to estimate the oil-water mixing ratio according to the actual incident angle value θ corresponding to the oil region pixel and the observation ratio corresponding to the oil region pixel
The oil-water mixing ratio lookup table is searched to obtain the estimated value of the oil-water mixing ratio of the oil film corresponding to the oil area pixel
Optionally, the observation ratio calculating module 201 in the apparatus 200 for estimating an oil-water mixing ratio is further configured to calculate a covariance matrix C corresponding to a water area pixel element near the oil area pixel based on the CPSAR observation data of the water area near the oil areaCPMain pair ofObserved ratio of angular elements
As shown by a dashed line box in fig. 2, the estimation apparatus 200 of the oil-water mixture ratio further includes:
ocean surface inclination angle estimation Module 205 for the dielectric constant of Water based on the NRCS equation
Observation ratio
And the ratio of the theoretical calculation
Approximately equal preconditions, and the pixel local angle of incidence value θiCalculating an estimate of the sea surface inclination angle of the water area from the above-mentioned angular relationship between the angle of incidence value theta, the azimuth and the distance-to-sea surface inclination angle (psi, zeta)
An oil-water mixing ratio lookup table construction module 207 for constructing an estimation value based on the marine surface inclination angle (psi, zeta) of the oil region and the marine surface inclination angle of the water region
Under the same precondition and the angle relation, the local incidence angle value theta of the oil area pixel corresponding to all the different pixel incidence angle values theta with the angle interval of the first specified value is calculatediAll different oil-water mixing ratios w with numerical intervals of a second specified value0Corresponding different oil-water mixed dielectric constants epsilonrLocal incidence angle value theta of pixels in different oil areasiAnd dielectric constant epsilon of different oil-water mixturesrCorresponding different oil-water mixture alphaHHAnd alphaVVBased on the inclination angle (psi, zeta) of the ocean surface in the oil region, different incidence angle values theta, and local incidence angle values theta of different oil region pixelsiA main shaft ofMixed with oil water alphaHHAnd alphaVVCalculating different oil-water mixtures gammaHH、ΓVVAnd ΓHVAnd different oil-water mixing theory calculated ratios
And constructing an oil-water mixing rate lookup table.
In connection with the above-mentioned estimation method of the sea surface oil spill oil-water mixing ratio, a computer readable storage medium is also proposed, on which a computer program is stored, which when executed by a processor implements the steps of the above-mentioned method.
In combination with the above estimation method of the sea surface oil-water mixture ratio, a computing device is also proposed, which comprises a memory, a processor and a computer program stored on the memory and operable on the processor, wherein the processor implements the steps of the above method when executing the program.
According to the technical scheme, the oil-water mixing rate of the sea surface spilled oil can be accurately estimated by combining the remote sensing observation data of the (satellite-borne, airborne and shipborne) CPSAR; the oil-water mixing rate of the sea surface oil film can be effectively inverted in real time by combining a lookup table; the calculation time is short, and the method is suitable for real-time observation of oil spill events; and parallel calculation can be combined to obtain smaller processing time delay and enhance the real-time performance of processing.
The above-described aspects may be implemented individually or in various combinations, and such variations are within the scope of the invention.
It will be understood by those of ordinary skill in the art that all or some of the steps of the methods, systems, functional modules/units in the devices disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. In a hardware implementation, the division between functional modules/units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be performed by several physical components in cooperation. Some or all of the components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on computer readable media, which may include computer storage media (or non-transitory media) and communication media (or transitory media). The term computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, as is well known to those of ordinary skill in the art. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by a computer. In addition, communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media as known to those skilled in the art.
Finally, it should be noted that: the above examples are only for illustrating the technical solutions of the present invention, and are not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for estimating the mixing rate of oil and water spilled on the sea surface is characterized by comprising the following steps:
calculating a covariance matrix C corresponding to an oil area pixel based on CPSAR observation data of the oil areaCPObserved ratio of major diagonal elements of
According to the actual incidence angle value theta corresponding to the oil area pixel and the observation ratio value corresponding to the oil area pixel
Searching an oil-water mixing rate lookup table to obtain an estimated value of the oil-water mixing rate of the oil film corresponding to the oil area pixel
Wherein the covariance matrix CCPThe formula of (1) is as follows:
wherein,
representing approximately equal to, representing the conjugate transpose,<·>representing the ensemble averaging of a number of adjacent pixels for speckle noise removal, SpqDenotes the complex scattering coefficient, SpqSubscripts p, q in (1) are polarization modes of transmitting and receiving electromagnetic waves of the CPSAR, HH denotes horizontal polarization, VV denotes vertical polarization, HV and VH denote cross polarization,
a formula representing the normalized radar backscattering cross section NRCS in the tilted-Bragg scattering mode,
the formula of the NRCS is as follows:
wherein k isrA radar wave number representing the CPSAR, W (-) representing a wave spectrum function of a Bragg wave number describing the roughness of the sea surface, a reflection function ΓpqThe formula of (1) is as follows:
wherein,
wherein,
where ψ and ζ are the azimuth and distance-to-sea surface inclination angles, θ, respectivelyiIs a local incidence angle value, w, corresponding to an actual incidence angle value theta corresponding to the oil region pixel0Is the oil-water mixing ratio, w0A value of 0 or more and 1 or less,
is the dielectric constant of the oil and is,
is the dielectric constant of water,. epsilonrAnd the actual dielectric constant of the oil film corresponding to the oil area pixel.
2. The method of estimating an oil-water mixing ratio according to claim 1, further comprising:
calculating a covariance matrix C corresponding to the water area pixels near the oil area based on the CPSAR observation data of the water area near the oil areaCPObserved ratio of major diagonal elements of
Dielectric constant of water based on the NRCS formula
Observation ratio
And the ratio of the theoretical calculation
Approximately equal preconditions, and the pixel local angle of incidence value θiThe following angular relationships between the angle of incidence value θ, the azimuth and the angle of inclination of the distance to the ocean surface (ψ, ζ):
θi＝cos-1[cos(θ+ψ)cosζ]
calculating the estimated value of the surface inclination angle of the ocean in the water area
Wherein the water zone ocean surface inclination angle estimate
The following relation is satisfied:
estimating the sea surface inclination angle (psi, zeta) of the oil region and the water region based on the sea surface inclination angle
Under the same precondition and the angle relation, the local incidence angle value theta of the oil area pixel corresponding to all the different pixel incidence angle values theta with the angle interval of the first specified value is calculatediAll different oil-water mixing ratios w with numerical intervals of a second specified value0Corresponding different oil-water mixed dielectric constants epsilonrLocal incidence angle value theta of pixels in different oil areasiAnd dielectric constant epsilon of different oil-water mixturesrCorresponding different oil-water mixture alphaHHAnd alphaVVBased on the inclination angle (psi, zeta) of the ocean surface in the oil region, different incidence angle values theta, and local incidence angle values theta of different oil region pixelsiAlpha of different oil-water mixtureHHAnd alphaVVCalculating different oil-water mixtures gammaHH、ΓVVAnd ΓHVAnd different oil-water mixing theory calculated ratios
And constructing the oil-water mixing rate lookup table.
3. The method according to claim 1 or 2, wherein the covariance matrix C corresponding to the pixels in the oil region is calculatedCPObserved ratio of major diagonal elements of
Then, the observation ratio of each pixel with the signal-to-noise ratio greater than the preset threshold value in one oil area pixel and the adjacent pixels to be calculated is calculated
The average value of the calculation is used as a new value corresponding to the oil area pixel to be calculatedObservation ratio
4. The method of estimating an oil-water mixing ratio according to claim 2, wherein the first specified value is 1 degree or less, and the second specified value is 0.1 or less.
5. An apparatus for estimating a sea surface spill oil-water mixing ratio, comprising:
an observation ratio calculation module used for calculating a covariance matrix C corresponding to the oil area pixel based on the CPSAR observation data of the oil areaCPObserved ratio of major diagonal elements of
An oil-water mixing ratio estimation module for estimating the actual incidence angle value theta corresponding to the oil region pixel and the observation ratio value corresponding to the oil region pixel
Searching an oil-water mixing rate lookup table to obtain an estimated value of the oil-water mixing rate of the oil film corresponding to the oil area pixel
Wherein the covariance matrix CCPThe relationship of (A) is as follows:
wherein,
representing approximately equal to, representing the conjugate transpose,<·>representing a plurality of adjacent picture elementsPerforming ensemble averaging for removing speckle noise, SpqDenotes the complex scattering coefficient, SpqSubscripts p, q in (1) are polarization modes of transmitting and receiving electromagnetic waves of the CPSAR, HH denotes horizontal polarization, VV denotes vertical polarization, HV and VH denote cross polarization,
a relation expressing the normalized radar backscattering cross section NRCS under the tilted-Bragg scattering mode,
the NRCS has the following relation:
wherein k isrA radar wave number representing the CPSAR, W (-) representing a wave spectrum function of a Bragg wave number describing the roughness of the sea surface, a reflection function ΓpqThe formula of (1) is as follows:
wherein,
wherein,
where ψ and ζ are the azimuth and distance-to-sea surface inclination angles, θ, respectivelyiIs a local incidence angle value, w, corresponding to an actual incidence angle value theta corresponding to the oil region pixel0Is the oil-water mixing ratio, w0The value thereof is 0 or more and 1 or less,
is the dielectric constant of the oil and is,
is the dielectric constant of water,. epsilonrAnd the actual dielectric constant of the oil film corresponding to the oil area pixel.
6. The apparatus according to claim 5, wherein the observation ratio calculating module is further configured to calculate a covariance matrix C corresponding to the pixels of the water area near the oil area based on the CPSAR observation data of the water area near the oil areaCPObserved ratio of major diagonal elements of
The estimation apparatus further includes:
an ocean surface inclination angle estimation module for estimating the dielectric constant of water based on the NRCS formula
Observation ratio
And the ratio of the theoretical calculation
Approximately equal preconditions, and the pixel local angle of incidence value θiThe following angular relationships between the angle of incidence value θ, the azimuth and the angle of inclination of the distance to the ocean surface (ψ, ζ):
θi＝cos-1[cos(θ+ψ)cosζ]
calculating the estimated value of the surface inclination angle of the ocean in the water area
Wherein the water zone ocean surface inclination angle estimate
The following relation is satisfied:
an oil-water mixing ratio lookup table construction module for constructing a lookup table based on the marine surface inclination angle (psi, zeta) of the oil region and the marine surface inclination angle estimation value of the water region
Under the same precondition and the angle relation, the local incidence angle value theta of the oil area pixel corresponding to all the different pixel incidence angle values theta with the angle interval of the first specified value is calculatediAll different oil-water mixing ratios w with numerical intervals of a second specified value0Corresponding different oil-water mixed dielectric constants epsilonrLocal incidence angle value theta of pixels in different oil areasiAnd dielectric constant epsilon of different oil-water mixturesrCorresponding different oil-water mixture alphaHHAnd alphaVVBased on the inclination angle (psi, zeta) of the ocean surface in the oil region, different incidence angle values theta, and local incidence angle values theta of different oil region pixelsiAlpha of different oil-water mixtureHHAnd alphaVVCalculating different oil-waterHybrid gammaHH、ΓVVAnd ΓHVAnd different oil-water mixing theory calculated ratios
And constructing the oil-water mixing rate lookup table.
7. The apparatus according to claim 5 or 6, wherein the observation ratio calculation module calculates the covariance matrix C corresponding to the pixels of the oil regionCPObserved ratio of major diagonal elements of
Then, the observation ratio of each pixel with the signal-to-noise ratio greater than the preset threshold value in one oil area pixel and the adjacent pixels to be calculated is calculated
The average value of the obtained values is used as a new observation ratio value corresponding to the oil area pixel to be calculated
8. The apparatus for estimating a mixing ratio of oil and water according to claim 6, wherein the first specified value is 1 degree or less and the second specified value is 0.1 or less.
9. A computer-readable storage medium, characterized in that the storage medium has stored thereon a computer program which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 4.
10. A computing device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the method of any one of claims 1 to 4 when executing the program.
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