Method and device for measuring and calculating methane emission flux of landfill and medium

Abstract

The invention relates to the field of landfill methane emission remote sensing monitoring, and discloses a landfill methane emission flux measuring and calculating method and device and a medium, and the method comprises the following steps: based on regional satellite TROPOMI observation data, carrying out qualitative analysis on annual average methane emission signals of a landfill, and determining a target landfill according to a qualitative analysis result; based on data of a satellite-borne hyperspectral imager, the methane emission flux of the target landfill is quantitatively measured and calculated, and the position of a methane emission hot spot area in the target landfill is determined; and positioning the position of an emission source in the target landfill through an active methane laser detection lens carried by an unmanned aerial vehicle platform, and independently calculating the methane emission flux of the target landfill by adopting an upper and lower section method. Based on the method, the annual average methane emission condition of the landfill can be rapidly and accurately evaluated, the methane emission flux of the whole landfill is obtained, and the internal emission hot spot area of the landfill is positioned.

Description

Technical Field

[0001] The present invention relates to the field of remote sensing monitoring of methane emissions from landfills, and more specifically, to a method, device and medium for measuring the methane emission flux from a landfill. Background Art

[0002] The existing methods for calculating the methane emission rate of landfills are mainly divided into two categories: bottom-up inventory method and top-down measurement method. The bottom-up inventory method relies on specific statistical data of the landfill (such as the landfill volume over the years, garbage composition, gas production potential, etc.) and a first-order decay model to estimate the methane emission flux. In the case of detailed statistical data, this method is relatively convenient, but its key parameters (such as methane gas production rate constant and methane gas production potential per unit mass of garbage) are often dependent on field experiments and have large uncertainties. In addition, many developing countries lack statistical data at the landfill site scale, which greatly limits the feasibility of the inventory method in practical applications.

[0003] The top-down landfill methane measurement methods mainly include ground monitoring and satellite data inversion. Traditional ground monitoring usually uses the static box method to directly measure the methane emission flux at different points in the landfill. This method uses a closed bottomless box to cover the surface, collects gas samples in the box at regular intervals, and calculates the rate of change of methane concentration in the sample gas over time to convert the methane emission rate on the surface. Although the static box method has high accuracy and strong reliability, it also has obvious limitations, such as being time-consuming and labor-intensive, and being greatly affected by terrain. In addition, due to the uncertainty of the distribution of methane leakage sources in the landfill, although the static box method can accurately quantify the methane emission flux at a specific point, it is difficult to cover the emission situation of the entire landfill.

[0004] In recent years, there are also some technologies that use drones equipped with active methane laser detection lenses to conduct qualitative detection of methane in landfills from top to bottom. For example, in the patent technology document with application number CN202210671233.9, a landfill methane flux measurement device and method with air-ground dual-field coupling is provided. In general, the advantages of drone platforms include high spatial resolution of acquired data, strong flexibility, ability to cover complex terrain, ability to capture small-scale or local emission sources, suitability for short-term high-frequency monitoring, and ability to identify the time-varying characteristics of emissions. And equipped with corresponding optical lenses, it has the ability to directly and accurately locate the leakage position inside the landfill. However, its limitations are also quite obvious, including limited monitoring range, difficulty in covering large-area landfills; sensitivity to weather conditions, wind speed, humidity, etc. will affect measurement accuracy; high operating costs, and difficulty in achieving large-scale long-term monitoring.

[0005] In contrast, satellite-based methane inversion technology has the ability to fully cover landfills, not only can it accurately locate methane emission hotspots, but also can support large-scale, long-term, and multiple revisit monitoring. In recent years, with the increase in the number of methane monitoring satellites and the continuous optimization of inversion algorithms, this technology has become an important tool for monitoring, verifying, and quantifying methane emissions worldwide. It provides an efficient and reliable solution for the comprehensive assessment of methane emissions from landfills, and has shown great potential in global-scale applications.

[0006] At present, spaceborne detection satellites can be divided into two categories: regional emission flux detection satellites and point source hyperspectral imagers. The typical representative of regional emission satellites is TROPOMI. TROPOMI is characterized by excellent global coverage and short revisit period, and can achieve daily global coverage. However, its resolution is low (about 5 km) and the detection limit of methane emission flux is high (about 5 t / h). Therefore, TROPOMI is suitable for inverting the total methane emission flux in a region, but it is difficult to distinguish the emission signals of different methane emission sources in the region. In particular, domestic landfills are located in urban areas with complex surface characteristics, high background noise, and many potential emission sources. At present, TROPOMI can only directly distinguish and capture the emission signals of dozens of the world's largest domestic waste landfills.

[0007] Another type of satellite-borne point source hyperspectral imager (such as EMIT, PRISMA, EnMAp, etc.) has a higher spatial resolution (30m / 60m) and a lower flux detection limit (~500kg / h), which can image and quantify methane emission plumes at the facility scale such as inside large emission sources (such as oil and gas plants, coal mine ventilation shafts, and large urban landfills). However, the revisit period of this type of instrument is long (usually about one month), and in actual observations, due to the influence of clouds, the number of successful observations that can be used for methane inversion is small, making it difficult to comprehensively evaluate the dynamic changes of methane emissions from landfills throughout the year. Summary of the invention

[0008] The present invention proposes a landfill methane emission flux measurement method, device and medium, which aims to combine the respective advantages of regional satellites, satellite-borne point source hyperspectral imagers, drones, ground monitoring and other platforms in detecting landfill methane emissions, solve the existing problems in the landfill methane emission signal evaluation technology of each single remote sensing platform, and provide technical support for methane control and emission reduction in domestic waste landfills.

[0009] According to a first aspect of the present invention, a method for calculating methane emission flux from a landfill is provided, the method comprising: Based on regional satellite TROPOMI observation data, the annual average methane emission signal of landfills was qualitatively analyzed, and target landfills were identified based on the qualitative analysis results; Based on the satellite-borne hyperspectral imager data, quantitatively calculate the methane emission flux of the target landfill and determine the location of the methane emission hotspot area inside the target landfill; The active methane laser detection lens carried by the UAV platform is used to locate the emission source inside the target landfill, and the upper and lower profile method is used to independently calculate the methane emission flux of the target landfill.

[0010] Furthermore, based on regional satellite TROPOMI observation data, the annual average methane emission signal of landfills was qualitatively analyzed, and the target landfills were determined based on the qualitative analysis results, including: Obtain TROPOMI observation data and preprocess the TROPOMI observation data; Based on the angle between the actual wind direction and the north direction on that day, the pre-processed TROPOMI observation data was rotated by the corresponding angle to perform a two-dimensional coordinate transformation. After the transformation, the smoke plume emission signal of the landfill is always facing the north direction. The calculation formula for the two-dimensional coordinate transformation of the pre-processed TROPOMI observation data is: , In the formula, and are the horizontal and vertical coordinate values ​​of longitude and latitude before wind direction rotation transformation, and They are the horizontal and vertical coordinate values ​​of longitude and latitude after wind direction rotation transformation, and are the latitude and longitude abscissa and ordinate values ​​of the landfill, respectively. It is the angle between the actual wind direction on that day and the true north direction; The spatial overlap area oversampling process was performed on the TROPOMI observation data before and after wind direction rotation, and the annual average methane concentration increment map of the landfill area was obtained. Based on the annual average methane concentration increment map of the landfill area, the mass balance method is used to quantitatively evaluate the methane emission signal of the landfill; Based on the results of spatial overlapping area oversampling and wind direction rotation, it is determined whether there is methane emission in the landfill. If there is methane emission, the landfill is taken as the target landfill.

[0011] Furthermore, the spatial overlapping area oversampling processing was performed on the TROPOMI observation data before and after the wind direction rotation, and the annual average methane concentration increment map of the landfill area was obtained, including: Setting a square grid centered on the longitude and latitude coordinates of the landfill; wherein the square grid includes a plurality of grids; The rotated TROPOMI daily observation data of the year are weighted averaged on the grid; the average weight adopts the ratio of the actual overlapping area of ​​the satellite's actual daily observation pixels and the preset pixels; all grid points are traversed to obtain the annual average methane concentration increment map of the landfill area.

[0012] Furthermore, based on the satellite-borne hyperspectral imager data, the methane emission flux of the target landfill is quantitatively calculated, and the location of the methane emission hotspot area inside the target landfill is determined, specifically including: Obtain the original radiation brightness data of the target landfill from the satellite-borne hyperspectral imager, including remote sensing image data with short-wave infrared bands. Calculate the methane unit absorption spectrum k under the set observation scene in the atmospheric radiation transmission simulation environment according to the actual observation conditions; wherein the actual observation conditions include the satellite sensor height, the ground elevation of the target landfill, the solar zenith angle, and the observation azimuth; Calculate the methane concentration increment of the target landfill based on the original radiance value of each pixel in the whole scene image and the methane unit absorption spectrum k ; Based on the methane concentration increment of the target landfill, determine the annual average methane concentration increment map of the target landfill area, visually interpret the location of the hot spot emission area inside the target landfill, and quantitatively calculate the methane emission rate of the target landfill using the following formula: , In the formula, is the methane emission rate, is the effective wind speed at 10m at the landfill site, For the j Pixel area, is the number of pixels in the smoke plume after masking, For the j The methane mass increment in each pixel is is the effective length of the plume, specifically defined as the power of half the area of ​​the plume behind the mask.

[0013] Furthermore, the target landfill methane concentration increment The calculation formula is: , In the formula, is the average radiance value of the entire scene image, is the original radiation brightness value of each pixel in the whole scene image, The covariance matrix of the band selected for calculation of the whole scene image, T represents the transpose of the matrix.

[0014] Furthermore, the methane concentration increment of the target landfill is calculated based on the original radiance value of each pixel in the whole scene image and the methane unit absorption spectrum k. , specifically including: The methane concentration increment of the target landfill is calculated using the dual channels of the 1600-1900nm methane weak absorption band and the 2150-2500nm methane strong absorption band in the short-wave infrared band. The covariance value of the radiation brightness value within the dual-channel full-scene image is used as the weight to calculate the new methane concentration increment of the target landfill after weighted average. The methane concentration increment of the target landfill is iterated to further filter and remove background noise; wherein, the calculation formula for iterating the methane concentration increment of the target landfill is: , In the formula, i is the number of iterations, To remove the simulated background value of the target landfill after methane concentration increment is removed, is the original radiance value of the image.

[0015] Furthermore, the emission source position inside the target landfill is located by using the active methane laser detection lens carried by the UAV platform, and the methane emission flux of the target landfill is independently calculated using the upper and lower profile method, including: Using drones equipped with active methane laser detection lenses and wind speed and direction sensors, regional inspections are carried out on the hotspot emission areas of target landfills obtained through satellite monitoring to obtain monitoring concentration data; wherein the monitoring concentration data includes methane concentration data and site wind speed and direction data; Import the monitoring concentration data into a geographic information system, use an interpolation algorithm to generate a spatial distribution map of the methane concentration on the landfill surface, identify hotspot areas with abnormally elevated methane concentrations, and clarify their distribution range and location; combine time series analysis to evaluate the dynamic change trend of hotspot areas, screen out persistent hotspot areas, and locate the specific location of methane emission sources inside the landfill; Based on the spatial distribution map of methane concentration obtained by drone inspection, the upper and lower profile method was used to calculate the methane emission flux in the hot spot area. The consistency and reliability of the flux calculation results were verified through repeated calculations.

[0016] Furthermore, based on the spatial distribution map of methane concentration obtained by drone inspection, the upper and lower profile method was used to calculate the methane emission flux in the hot spot area. The consistency and reliability of the flux calculation results were verified through repeated calculations, including: Comparative analysis was conducted on the concentration distribution monitoring results from satellites and drones to divide the emission source area. Multiple profiles were planned in the upwind and downwind areas of the emission source area. Based on the concentration difference detected upwind and downwind of the emission source, the emission rate of the emission source is obtained by integrating the concentration difference in the vertical section of wind direction with the wind speed. The calculation process is expressed as: , In the formula, is the emission flux of the emission source; is the integrated height of the plane perpendicular to the wind direction; is the integrated width of the plane perpendicular to the wind direction; is the wind speed vertical to the aerial survey plane; CH 4 Concentration signal enhancement value, CH measured by drone 4 Concentration signal value, is the background methane concentration value, is the emission flux of the lower profile, is the emission flux of the upper profile; Multiple groups of up and down wind direction profiles were taken for repeated calculation and averaged to verify the consistency and reliability of the flux calculation results between the UAV platform and the satellite platform.

[0017] According to a second aspect of the present invention, a landfill methane emission flux measurement device is provided, the device comprising: A signal evaluation module is configured to perform a qualitative analysis on the annual average methane emission signal of the landfill based on regional satellite TROPOMI observation data, and determine the target landfill according to the qualitative analysis results; A first flux calculation module is configured to quantitatively calculate the methane emission flux of the target landfill based on the satellite-borne hyperspectral imager data, and determine the location of the methane emission hotspot area inside the target landfill; The second flux measurement module is configured to locate the emission source inside the target landfill through the active methane laser detection lens carried by the UAV platform, and independently calculate the methane emission flux of the target landfill using the upper and lower profile method.

[0018] According to a third aspect of the present invention, there is provided a readable storage medium storing one or more programs, wherein the one or more programs can be executed by one or more processors to implement the method as described above.

[0019] The present invention has at least the following beneficial effects: 1. The present invention sacrifices the temporal resolution of TROPOMI observation data in exchange for higher spatial resolution, so that it has the ability to evaluate the point source methane emission signals of landfills in complex urban background areas.

[0020] 2. The present invention quantitatively measures the methane emission flux of the target landfill and determines the position of the methane emission hotspot area inside the target landfill based on the satellite-borne hyperspectral imager data. It can more accurately quantify the overall methane emission rate of the landfill at the time of satellite transit and locate the methane emission hotspot area inside the landfill. It fully considers the influence of observation conditions (such as solar zenith angle, ground altitude and sensor operating altitude), and more accurately estimates the background average radiation intensity value and the background covariance matrix through an iterative process.

[0021] 3. The present invention can further use an unmanned aerial vehicle platform to accurately locate the internal emission source position of the landfill based on the methane emission hotspot area of ​​the target landfill obtained by satellite monitoring, and independently calculate the methane emission flux in the hotspot emission area of ​​the landfill. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A flow chart of a method for calculating methane emission flux from a landfill according to an embodiment of the present invention is shown.

[0023] Figure 2 A schematic diagram showing comparison of landfill TROPOMI data before and after wind direction rotation according to an embodiment of the present invention is shown.

[0024] Figure 3 A schematic diagram shows the results of directly performing spatial overlapping area oversampling processing on the TROPOMI observation signals of the case landfill in 2021 according to an embodiment of the present invention.

[0025] Figure 4 A schematic diagram comparing the recognition results of the original matched filtering algorithm and the optimized matched filtering algorithm according to an embodiment of the present invention is shown; wherein a is a schematic diagram of the effect of the original matched filtering algorithm; and b is a schematic diagram of the effect of the optimized matched filtering algorithm.

[0026] Figure 5 A schematic diagram of the methane concentration distribution results of a landfill surveyed by a drone according to an embodiment of the present invention is shown.

[0027] Figure 6 A structural diagram of a landfill methane emission flux measurement device according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments, but are not intended to limit the present invention. For the various steps described herein, if there is no necessity for a causal relationship between each other, the order in which they are described as examples herein should not be regarded as a limitation, and those skilled in the art should know that they can be adjusted in order, as long as the logic between them is not destroyed, resulting in the inability to implement the entire process.

[0029] The embodiment of the present invention provides a method for calculating the methane emission flux of a landfill. Figure 1 As shown, it is a flow chart of the method, which includes the following steps S100 to S300, which are described in detail as follows: S100: Based on regional satellite TROPOMI observation data, qualitative analysis of the annual average methane emission signal of landfills is carried out, and target landfills are determined based on the qualitative analysis results.

[0030] In step S100, the rapid evaluation and quantitative method of landfill methane emission signals based on regional satellite TROPOMI observation data based on wind direction rotation and spatial overlap area oversampling technology will help to quickly determine the comprehensive methane emission of landfills within a certain time range. If the average methane concentration value near the location of the landfill after spatial overlap area processing is significantly increased compared with the surrounding background value, and a northward plume signal appears after wind direction rotation processing, it can be proved that the landfill has an obvious methane emission signal; the landfill currently under qualitative analysis is used as the target landfill to perform subsequent steps S200 and S300.

[0031] In some embodiments, step S100 includes the following steps S101 to S104.

[0032] S101: Acquire TROPOMI observation data and preprocess the TROPOMI observation data.

[0033] Specifically, in step S101, the raw data of each daily observation orbit of TROPOMI can be merged and filtered according to the quality index QA ≥ 0.4, short-wave infrared (SWIR) aerosol optical thickness < 0.13, and SWIR surface albedo > 0.02. Considering that urban domestic waste landfills are usually located in urban suburbs with complex landforms or in valleys with large terrain undulations, this relaxed filtering standard can significantly improve data coverage compared to the conventional QA=1 in this field. As an example only, the way to merge the raw data of each daily observation orbit of TROPOMI can be to download the raw methane column concentration observation products of all daily observation orbits from the Copernicus Data Center of the European Space Agency, and merge the raw data of each daily observation orbit.

[0034] S102: Perform wind direction rotation processing on the pre-processed TROPOMI observation data. Calculate the angle between the actual wind direction of the day and the north direction, rotate the corresponding angle, and perform two-dimensional coordinate transformation on the TROPOMI observation data. This ensures that no matter what the actual wind direction is on the day, the smoke plume emission signal of the landfill is always facing the north direction after the transformation.

[0035] In this embodiment, the specific calculation formula for performing two-dimensional coordinate transformation on TROPOMI observation data is as follows: , In the formula, and are the horizontal and vertical coordinate values ​​of longitude and latitude before wind direction rotation transformation, and They are the horizontal and vertical coordinate values ​​of longitude and latitude after wind direction rotation transformation, and are the latitude and longitude abscissa and ordinate values ​​of the landfill, respectively. It is the angle between the actual wind direction on that day and due north.

[0036] S103: Perform spatial overlapping area oversampling processing on the TROPOMI observation data before and after wind direction rotation processing, respectively, to obtain an annual average methane concentration increment map of the landfill area with a high spatial resolution.

[0037] In some embodiments, step S103 includes the following steps S1031 to S1033.

[0038] S1031: predefine a square grid with the latitude and longitude coordinates of the landfill as the center, a size of 0.5° × 0.5°, and a resolution of 0.01° × 0.01°; the square grid includes a plurality of grids.

[0039] S1032: Perform weighted averaging of the rotated TROPOMI daily observation data over a year on a 0.5° × 0.5° grid. The average weight is the ratio of the actual overlap area between the actual daily satellite observation pixels and the predefined 0.01° × 0.01° pixels in step S1031. Traverse all grids to obtain a 0.01° × 0.01° high spatial resolution annual average methane concentration increment map of the landfill area; S1033: Clip the above 0.5° × 0.5° grid to a range of 0.25° × 0.25° centered on the longitude and latitude coordinates of the landfill. The actual length of the methane emission plume from the landfill is usually within a length range of 20 km. Regional clipping can effectively avoid interference from other potential emission sources near the landfill while retaining the continuity of the image boundary.

[0040] S104: Based on the annual average methane concentration increment map of the landfill area obtained in step S103, a mass balance method is used to perform a preliminary quantitative assessment of the landfill methane emission signal.

[0041] For example, Figures 2 to 3 As shown. After the spatial overlap area oversampling process, Figure 2 It can be observed that the methane concentration value near the central coordinate is significantly higher than the surrounding background value. After further wind direction rotation processing, Figure 3 It can be clearly observed that there is a methane plume signal facing due north at the marked location of the landfill. Combining the results of spatial overlapping area oversampling and wind direction rotation, it can be qualitatively determined that the target landfill has obvious methane emissions.

[0042] It should be noted that the current minimum detection limit of TROPOMI single-day observation of point source methane emissions is about 5 t / h, and the actual methane emission rate values ​​of many small and medium-sized landfills are lower than this detection limit. Even if this method enhances the image of the methane emission signal of the target landfill based on long-term series data, in general, this method is only sufficient but not necessary to determine whether there is obvious methane emission in the landfill. Subsequent use of satellite-borne hyperspectral and drone platforms with lower detection limits is required to further determine the location of the emission hotspot area and the specific methane emission rate of the target landfill.

[0043] S200: Based on the satellite-borne hyperspectral imager data, quantitatively calculate the methane emission flux of the target landfill, and determine the location of the methane emission hotspot area inside the target landfill.

[0044] In some embodiments, a scenario-specific iterative matched filtering scheme based on hyperspectral data is proposed to perform step S200, so that the overall methane emission rate of the landfill can be more accurately and quantitatively estimated, and the methane emission hotspots inside the landfill can be located. The algorithm fully considers the influence of observation conditions (such as solar zenith angle, ground altitude, and sensor operating altitude), and estimates the background average radiation intensity value and background covariance matrix more accurately through an iterative process. Compared with the traditional matched filtering algorithm, the scheme proposed in the present invention has significant advantages in inverting the methane emission plume of the landfill.

[0045] Specifically, step S200 is executed by the following steps S201 to S204.

[0046] S201: Obtain the original radiation brightness data of the target landfill from the satellite-borne hyperspectral imager, including but not limited to remote sensing image data with short-wave infrared band (1000-2500nm) such as (EMIT, PRISMA, EnMap, GF5, GF5B, ZY1-02D). The original radiation brightness value of each pixel in the whole scene image is recorded as .

[0047] S202: Calculate the methane unit absorption spectrum k under the specific observation scenario in the atmospheric radiation transmission simulation software modtran according to the actual observation conditions of the specific scenario (including the satellite sensor height, the ground elevation of the target landfill, the solar zenith angle, and the observation azimuth).

[0048] S203: Preliminary calculation of the methane concentration increment of the target landfill using the least squares method (Unit: ppm*m); the specific calculation formula is: , In the formula, is the average radiance value of the entire scene image, is the original radiation brightness value of each pixel in the whole scene image, The covariance matrix of the band selected for calculation of the whole scene image, T represents the transpose of the matrix.

[0049] In some embodiments, step S203 includes the following steps S2031 and S2032.

[0050] S2031: Use the short-wave infrared band of 1600-1900nm methane weak absorption band and 2150-2500nm methane strong absorption band to calculate the methane concentration increment of the target landfill site Then, the covariance value of the radiation brightness values ​​within the entire image range of the two scenes is used as the weight to calculate the new target landfill methane concentration increment after weighted average. .

[0051] The principle of step S2031 is that the 2150-2500nm methane strong absorption band is highly sensitive to methane gas absorption, but the radiation spectrum signal-to-noise ratio is low; while the 1600-1900nm methane weak absorption band is less sensitive to methane gas absorption, but the radiation spectrum signal-to-noise ratio is high. In the inversion background of urban areas where domestic landfills are located, where the surface characteristics are complex, the background noise is high, and there are many potential emission sources, dual-channel processing can effectively suppress the background noise of the methane concentration increment map obtained in this step; S2032: Increase in methane concentration at target landfills Iterate and further filter to remove background noise.

[0052] The principle of step S2032 is to calculate the methane concentration increment of the target landfill according to the least squares method. The process is based on the original radiance value of the whole scene image under normal circumstances Normal distribution However, the presence of methane plume signals near the target landfill will affect the as well as Therefore, it is necessary to eliminate the impact of potential methane emission sources in the original radiance data in order to more accurately assess as well as , the specific calculation formula is as follows: , Where i is the number of iterations, and the entire iterative process usually converges after 15-30 iterations; To remove the simulated background value of the target landfill after methane concentration increment is removed, is the original radiance value of the image.

[0053] S204: Based on the target landfill area annual average methane concentration increment map obtained in step S203, visually interpret the location of the hot spot emission area inside the landfill, and use the mass balance method to quantitatively calculate the methane emission rate of the target landfill.

[0054] In some embodiments, step S204 includes the following steps S2041 and S2042.

[0055] S2041: Selecting an 80% confidence interval, performing a Student's t-test and Gaussian filtering on the target landfill methane concentration increment map obtained in step S203, and obtaining a masked target landfill methane plume; S2042: Use the mass balance method to estimate the annual average methane emission rate of the target landfill. The specific calculation formula is: , In the formula, is the methane emission rate, is the effective wind speed at 10m at the landfill site, For the j pixel area (0.01° × 0.01°), is the number of pixels in the smoke plume after masking, For the j The methane mass increment in each pixel can be converted from the ideal gas state equation through the methane column concentration increment. is the effective length of the plume, specifically defined as the power of half the area of ​​the plume behind the mask.

[0056] For example, Figure 4 The EMIT 30m spatial resolution data of a domestic waste landfill (87.85E, 44.04N) on August 18, 2022 provided by the embodiment of the present invention is a schematic diagram comparing the effects of inverting the methane concentration increment using the original and specific scenario iterative matched filtering algorithms. It can be seen that the inversion result of the specific scenario iterative matched filtering algorithm has less background noise than the original matched filtering algorithm, the internal gradient descent structure of the plume is smoother, and the hot spot area is more obvious. Figure 4 The visual interpretation shown in b obtained the methane hotspot emission area inside the landfill, providing key target observation locations for subsequent drone platforms and ground static boxes. The final calculation result of the methane emission flux of the landfill on August 18, 2022 was 9.4±0.8t / h.

[0057] It should be noted that the current revisit period of the satellite-borne hyperspectral observation platform is relatively long, with an average revisit time of one month. Considering the influence of clouds in actual observations, the number of possible successful observations is even less. Therefore, it is difficult to conduct long-term series monitoring of the target landfill. Although the actual landfill is a continuous emission source, its emission rate is affected by atmospheric factors such as humidity, rainfall, temperature, and landfill operation and management measures (such as landfill surface coverage, landfill garbage volume and composition, and landfill gas collection system usage), showing large dynamic fluctuations. Therefore, the analysis results of the TROPOMI data in step S100 and the subsequent measurement data of the UAV platform and the ground static box can be combined to conduct a more comprehensive comprehensive evaluation of the methane emissions of the target landfill within a certain time range.

[0058] S300: Using the active methane laser detection lens carried by the UAV platform, the emission source position inside the target landfill is located, and the methane emission flux of the target landfill is independently calculated using the upper and lower profile method.

[0059] The purpose of step S300 is to further use the drone platform to accurately locate the internal emission source of the landfill based on the methane emission hotspot area of ​​the target landfill obtained by satellite monitoring, and independently calculate the methane emission flux in the hotspot emission area of ​​the landfill.

[0060] In some embodiments, step S300 is implemented by the following steps S301 to S303.

[0061] S301: Data collection. Use drones equipped with active methane laser detection lenses and wind speed and direction sensors to conduct regional inspections of the target landfill hotspot emission areas obtained through satellite monitoring, and collect data on methane concentration and site wind speed and direction.

[0062] S302: Hotspot location. The collected monitoring concentration data is imported into the geographic information system, and the spatial distribution map of the methane concentration on the landfill surface is generated using the interpolation algorithm. The hotspot areas with abnormally high methane concentrations are identified, and their distribution range and location are clarified. Combined with time series analysis, the dynamic change trend of the hotspot areas is evaluated, and persistent hotspot areas are screened out to accurately locate the specific location of the methane emission source inside the landfill.

[0063] In some embodiments, step S302 includes the following steps S3021 to S3023.

[0064] S3021: Input the collected methane concentration data of each discrete point in the methane emission hotspot area into the geographic information system, and generate a spatial distribution map of the methane concentration on the landfill surface through an interpolation algorithm (such as ordinary Kriging interpolation); S3022: Based on the generated concentration distribution map, use a clustering algorithm to identify areas with abnormally elevated methane concentrations and clarify the distribution range and specific locations of hot spots; S3023: Combined with the time series analysis of concentration data, the dynamic trend of hotspot areas is evaluated to screen out persistent hotspot areas.

[0065] S303: Flux quantification. Based on the methane concentration distribution map obtained by drone inspection, the upper and lower profile method is used to calculate the methane emission flux in the hot spot area. The consistency and reliability of the flux calculation results are verified through repeated calculations.

[0066] In some embodiments, step S303 includes the following steps S3031 to S3033.

[0067] S3031: Compare and analyze the satellite and drone concentration distribution monitoring results to divide the emission source area. Plan multiple profiles in the upwind and downwind areas of the emission source.

[0068] S3032: Based on the concentration difference detected upwind and downwind of the emission source, the concentration difference is integrated with the wind speed in the vertical section of the wind direction to obtain the emission rate of the emission source. The calculation process is expressed as: , In the formula, is the emission flux of the emission source, g / s; is the profile emission flux, g / s; is the integrated height of the plane perpendicular to the wind direction, m; is the integrated width of the plane perpendicular to the wind direction, m; is the wind speed vertical to the aerial survey plane, m / s; CH 4 Concentration signal enhancement value, ppm. Usually, the upper wind direction test value is the background value, and the difference between the lower wind direction test value and the background value is recorded as the methane concentration signal enhancement value. CH measured by drone 4 Concentration signal value, is the background methane concentration value, is the emission flux of the lower profile, is the emission flux of the upper profile.

[0069] S3033: Take multiple groups of up and down wind direction profiles for repeated calculations and take the average value to verify the consistency and reliability of the flux calculation results of the UAV platform and the satellite platform.

[0070] For example, Figure 5 This is a schematic diagram of the methane concentration distribution obtained by aerial surveying a landfill using a drone equipped with a laser methane detection device. The laser methane detection device densely samples the site to obtain high-resolution methane concentration data. Based on geostatistical analysis in geographic information processing software, Kriging interpolation is performed on the aerial survey methane concentration data. It can be observed that Figure 6 There is a clear trend of methane emissions gathering in the image, and the area where the methane emission source is located can be clearly observed on the right side of the image. After the emission source is located, a static box can be deployed on the ground to monitor its methane emission rate and compare and verify it with the quantitative results of satellite drones and platforms.

[0071] It should be noted that when using drones equipped with laser methane detection equipment to conduct aerial surveys of landfills, key factors such as flight planning, equipment calibration, data collection, and post-analysis need to be comprehensively considered. The flight altitude, speed, and route overlap must be reasonably designed, and attention should be paid to the influence of equipment calibration, sampling frequency matching, and meteorological conditions, such as wind speed, wind direction, temperature, and humidity. During aerial surveys, the equipment status should be monitored in real time, abnormal data should be eliminated, and GIS technology should be used to visualize the distribution of methane concentrations and mark abnormal areas to provide a basis for subsequent management and control of methane emissions.

[0072] In some embodiments, after step S300, the landfill methane emission flux calculation method further includes step S400, deploying ground static boxes and meteorological stations in the hot spots inside the landfill obtained by the above-mentioned satellite and UAV monitoring platforms to conduct long-term monitoring of the methane emission flux in the hot spots.

[0073] In step S400, the ground weather station can obtain the actual wind speed and direction of the site, providing more accurate input parameters for satellite and UAV platforms to invert the landfill methane emission flux. At the same time, the weather station can also record important atmospheric factors that affect methane emissions, such as atmospheric pressure, humidity, and rainfall. By further analyzing the correlation between the landfill methane emission flux and these atmospheric factors, a scientific basis and theoretical support can be provided for controlling landfill methane emissions.

[0074] The embodiment of the present invention also provides a landfill methane emission flux measurement device, such as Figure 6 As shown, the device comprises: The signal evaluation module 601 is configured to perform a qualitative analysis on the annual average methane emission signal of the landfill based on the regional satellite TROPOMI observation data, and determine the target landfill according to the qualitative analysis results; The first flux calculation module 602 is configured to quantitatively calculate the methane emission flux of the target landfill based on the satellite-borne hyperspectral imager data, and determine the location of the methane emission hotspot area inside the target landfill; The second flux measurement module 603 is configured to locate the emission source inside the target landfill through the active methane laser detection lens carried by the UAV platform, and independently calculate the methane emission flux of the target landfill using the upper and lower profile method.

[0075] In some embodiments, the signal evaluation module is further configured to: Obtain TROPOMI observation data and preprocess the TROPOMI observation data; Based on the angle between the actual wind direction and the north direction on that day, the pre-processed TROPOMI observation data was rotated by the corresponding angle to perform a two-dimensional coordinate transformation. After the transformation, the smoke plume emission signal of the landfill is always facing the north direction. The calculation formula for the two-dimensional coordinate transformation of the pre-processed TROPOMI observation data is: , In the formula, and are the horizontal and vertical coordinate values ​​of longitude and latitude before wind direction rotation transformation, and are the horizontal and vertical coordinate values ​​of longitude and latitude after wind direction rotation transformation, and are the latitude and longitude abscissa and ordinate values ​​of the landfill, respectively. It is the angle between the actual wind direction on that day and the true north direction; The spatial overlap area oversampling process was performed on the TROPOMI observation data before and after wind direction rotation, and the annual average methane concentration increment map of the landfill area was obtained. Based on the annual average methane concentration increment map of the landfill area, the mass balance method is used to quantitatively evaluate the methane emission signal of the landfill; Based on the results of spatial overlapping area oversampling and wind direction rotation, it is determined whether there is methane emission in the landfill. If there is methane emission, the landfill is taken as the target landfill.

[0076] In some embodiments, the signal evaluation module is further configured to: Setting a square grid centered on the longitude and latitude coordinates of the landfill; wherein the square grid includes a plurality of grids; The rotated TROPOMI daily observation data of the year are weighted averaged on the grid; the average weight adopts the ratio of the actual overlapping area of ​​the satellite's actual daily observation pixels and the preset pixels; all grid points are traversed to obtain the annual average methane concentration increment map of the landfill area.

[0077] In some embodiments, the first flux calculation module is further configured to: Obtain the original radiation brightness data of the target landfill from the satellite-borne hyperspectral imager, including remote sensing image data with short-wave infrared bands. Calculate the methane unit absorption spectrum k under the set observation scene in the atmospheric radiation transmission simulation environment according to the actual observation conditions; wherein the actual observation conditions include the satellite sensor height, the ground elevation of the target landfill, the solar zenith angle, and the observation azimuth; Calculate the methane concentration increment of the target landfill based on the original radiance value of each pixel in the whole scene image and the methane unit absorption spectrum k ; Based on the methane concentration increment of the target landfill, determine the annual average methane concentration increment map of the target landfill area, visually interpret the location of the hot spot emission area inside the target landfill, and quantitatively calculate the methane emission rate of the target landfill using the following formula: , In the formula, is the methane emission rate, is the effective wind speed at 10m at the landfill site, For the j Pixel area, is the number of pixels in the smoke plume after masking, For the j The methane mass increment in each pixel is is the effective length of the plume, specifically defined as the power of half the area of ​​the plume behind the mask.

[0078] In some embodiments, the target landfill methane concentration increment The calculation formula is: , In the formula, is the average radiance value of the entire scene image, is the original radiation brightness value of each pixel in the whole scene image, The covariance matrix of the band selected for calculation of the whole scene image, T represents the transpose of the matrix.

[0079] In some embodiments, the first flux calculation module is further configured to: The methane concentration increment of the target landfill is calculated using the dual channels of the 1600-1900nm methane weak absorption band and the 2150-2500nm methane strong absorption band in the short-wave infrared band. The covariance value of the radiation brightness value within the dual-channel full-scene image is used as the weight to calculate the new methane concentration increment of the target landfill after weighted average. The methane concentration increment of the target landfill is iterated to further filter and remove background noise; wherein, the calculation formula for iterating the methane concentration increment of the target landfill is: , In the formula, i is the number of iterations, To remove the simulated background value of the target landfill after methane concentration increment is removed, is the original radiance value of the image.

[0080] In some embodiments, the second flux calculation module is further configured to: Using drones equipped with active methane laser detection lenses and wind speed and direction sensors, regional inspections are carried out on the hotspot emission areas of target landfills obtained through satellite monitoring to obtain monitoring concentration data; wherein the monitoring concentration data includes methane concentration data and site wind speed and direction data; Import the monitoring concentration data into a geographic information system, use an interpolation algorithm to generate a spatial distribution map of the methane concentration on the landfill surface, identify hotspot areas with abnormally elevated methane concentrations, and clarify their distribution range and location; combine time series analysis to evaluate the dynamic change trend of hotspot areas, screen out persistent hotspot areas, and locate the specific location of methane emission sources inside the landfill; Based on the spatial distribution map of methane concentration obtained by drone inspection, the upper and lower profile method was used to calculate the methane emission flux in the hot spot area. The consistency and reliability of the flux calculation results were verified through repeated calculations.

[0081] In some embodiments, the second flux calculation module is further configured to: Comparative analysis was conducted on the concentration distribution monitoring results from satellites and drones to divide the emission source area. Multiple profiles were planned in the upwind and downwind areas of the emission source area. Based on the concentration difference detected upwind and downwind of the emission source, the emission rate of the emission source is obtained by integrating the concentration difference in the vertical section of wind direction with the wind speed. The calculation process is expressed as: , In the formula, is the emission flux of the emission source; is the integrated height of the plane perpendicular to the wind direction; is the integrated width of the plane perpendicular to the wind direction; is the wind speed vertical to the aerial survey plane; CH 4 Concentration signal enhancement value, CH measured by drone 4 Concentration signal value, is the background methane concentration value, is the emission flux of the lower profile, is the emission flux of the upper profile; Multiple groups of up and down wind direction profiles were taken for repeated calculation and averaged to verify the consistency and reliability of the flux calculation results between the UAV platform and the satellite platform.

[0082] It should be noted that the various device structures described in this embodiment belong to the same technical concept as the previously described method, and achieve the same technical effect through the same principle, which will not be repeated here.

[0083] An embodiment of the present invention further provides a readable storage medium, which stores one or more programs. The one or more programs can be executed by one or more processors to implement the method described in any of the above embodiments.

[0084] In addition, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present invention with equivalent elements, modifications, omissions, combinations (e.g., various embodiments intersecting schemes), adaptations or changes. The elements in the claims are to be interpreted broadly based on the language adopted in the claims, and are not limited to the examples described in this specification or during the prosecution of this application, and the examples are to be interpreted as non-exclusive. Therefore, this specification and examples are intended to be considered as examples only, and the true scope and spirit are indicated by the following claims and the full scope of their equivalents.

[0085] The foregoing description is intended to be illustrative and not restrictive. For example, the above examples (or one or more aspects thereof) may be used in combination with each other. For instance, other embodiments may be utilized by those of ordinary skill in the art upon reading the above description. Additionally, in the above detailed description, various features may be grouped together to simplify the present invention. This should not be construed as an intention that the features of an unclaimed invention are necessary for any claim. On the contrary, the subject matter of the present invention may be less than all of the features of a particular embodiment of the invention. Thus, the following claims are hereby incorporated into the detailed description by way of example or embodiment, where each claim stands on its own as a separate embodiment, and it is contemplated that these embodiments may be combined with each other in various combinations or permutations. The scope of the present invention should be determined with reference to the appended claims and the full scope of equivalents to which those claims are entitled.

Claims

1. A method for calculating the methane emission flux of a landfill, characterized in that: The method comprises: Based on regional satellite TROPOMI observation data, the annual average methane emission signal of landfills was qualitatively analyzed, and target landfills were identified based on the qualitative analysis results; Based on the satellite-borne hyperspectral imager data, quantitatively calculate the methane emission flux of the target landfill and determine the location of the methane emission hotspot area inside the target landfill; The active methane laser detection lens carried by the UAV platform is used to locate the emission source inside the target landfill, and the upper and lower profile method is used to independently calculate the methane emission flux of the target landfill.

2. The method according to claim 1, characterized in that Based on regional satellite TROPOMI observation data, the annual average methane emission signal of landfills was qualitatively analyzed, and the target landfills were determined based on the qualitative analysis results, including: Obtain TROPOMI observation data and preprocess the TROPOMI observation data; Based on the angle between the actual wind direction and the north direction on that day, the pre-processed TROPOMI observation data was rotated by the corresponding angle to perform a two-dimensional coordinate transformation. After the transformation, the smoke plume emission signal of the landfill is always facing the north direction. The calculation formula for the two-dimensional coordinate transformation of the pre-processed TROPOMI observation data is: ， In the formula, and are the horizontal and vertical coordinate values ​​of longitude and latitude before wind direction rotation transformation, and They are the horizontal and vertical coordinate values ​​of longitude and latitude after wind direction rotation transformation, and are the latitude and longitude abscissa and ordinate values ​​of the landfill, respectively. It is the angle between the actual wind direction on that day and the true north direction; The spatial overlap area oversampling process was performed on the TROPOMI observation data before and after wind direction rotation, and the annual average methane concentration increment map of the landfill area was obtained. Based on the annual average methane concentration increment map of the landfill area, the mass balance method is used to quantitatively evaluate the methane emission signal of the landfill; Based on the results of spatial overlapping area oversampling and wind direction rotation, it is determined whether there is methane emission in the landfill. If there is methane emission, the landfill is taken as the target landfill.

3. The method according to claim 2, characterized in that The spatial overlapping area oversampling processing was performed on the TROPOMI observation data before and after wind direction rotation, and the annual average methane concentration increment map of the landfill area was obtained, including: Setting a square grid centered on the longitude and latitude coordinates of the landfill; wherein the square grid includes a plurality of grids; The rotated TROPOMI daily observation data of the year are weighted averaged on the grid; the average weight adopts the ratio of the actual overlapping area of ​​the satellite's actual daily observation pixels and the preset pixels; all grid points are traversed to obtain the annual average methane concentration increment map of the landfill area.

4. The method according to claim 1, characterized in that Based on the satellite-borne hyperspectral imager data, the methane emission flux of the target landfill is quantitatively calculated, and the location of the methane emission hotspot area inside the target landfill is determined, specifically including: Obtain the original radiation brightness data of the target landfill from the satellite-borne hyperspectral imager, including remote sensing image data with short-wave infrared bands. Calculate the methane unit absorption spectrum k under the set observation scene in the atmospheric radiation transmission simulation environment according to the actual observation conditions; wherein the actual observation conditions include the satellite sensor height, the ground elevation of the target landfill, the solar zenith angle, and the observation azimuth; Calculate the methane concentration increment of the target landfill based on the original radiance value of each pixel in the whole scene image and the methane unit absorption spectrum k ; Based on the methane concentration increment of the target landfill, determine the annual average methane concentration increment map of the target landfill area, visually interpret the location of the hot spot emission area inside the target landfill, and quantitatively calculate the methane emission rate of the target landfill using the following formula: ， In the formula, is the methane emission rate, is the effective wind speed at 10m at the landfill site, For the j Pixel area, is the number of pixels in the smoke plume after masking, For the j The methane mass increment in each pixel is is the effective length of the plume, specifically defined as the power of half the area of ​​the plume behind the mask.

5. The method according to claim 4, characterized in that Target landfill methane concentration increase The calculation formula is: ， In the formula, is the average radiance value of the entire scene image, is the original radiation brightness value of each pixel in the whole scene image, The covariance matrix of the band selected for calculation of the whole scene image, T represents the transpose of the matrix.

6. The method according to claim 4 or 5, characterized in that: Calculate the methane concentration increment of the target landfill based on the original radiance value of each pixel in the whole scene image and the methane unit absorption spectrum k , including: The methane concentration increment of the target landfill is calculated using the dual channels of the 1600-1900nm methane weak absorption band and the 2150-2500nm methane strong absorption band in the short-wave infrared band. The covariance value of the radiation brightness value within the dual-channel full-scene image is used as the weight to calculate the new methane concentration increment of the target landfill after weighted average. The methane concentration increment of the target landfill is iterated to further filter and remove background noise; wherein, the calculation formula for iterating the methane concentration increment of the target landfill is: ， In the formula, i is the number of iterations, To remove the simulated background value of the target landfill after methane concentration increment is removed, is the original radiance value of the image.

7. The method according to claim 1, characterized in that The active methane laser detection lens carried by the UAV platform is used to locate the emission source inside the target landfill, and the upper and lower profile method is used to independently calculate the methane emission flux of the target landfill, including: Using drones equipped with active methane laser detection lenses and wind speed and direction sensors, regional inspections are carried out on the hotspot emission areas of target landfills obtained through satellite monitoring to obtain monitoring concentration data; wherein the monitoring concentration data includes methane concentration data and site wind speed and direction data; Import the monitoring concentration data into a geographic information system, use an interpolation algorithm to generate a spatial distribution map of the methane concentration on the landfill surface, identify hotspot areas with abnormally elevated methane concentrations, and clarify their distribution range and location; combine time series analysis to evaluate the dynamic change trend of hotspot areas, screen out persistent hotspot areas, and locate the specific location of methane emission sources inside the landfill; Based on the spatial distribution map of methane concentration obtained by drone inspection, the upper and lower profile method was used to calculate the methane emission flux in the hot spot area. The consistency and reliability of the flux calculation results were verified through repeated calculations.

8. The method according to claim 7, characterized in that Based on the spatial distribution map of methane concentration obtained by drone inspection, the upper and lower profile method is used to calculate the methane emission flux in the hot spot area. The consistency and reliability of the flux calculation results are verified through repeated calculations, including: Comparative analysis was conducted on the concentration distribution monitoring results from satellites and drones to divide the emission source area. Multiple profiles were planned in the upwind and downwind areas of the emission source area. Based on the concentration difference detected upwind and downwind of the emission source, the emission rate of the emission source is obtained by integrating the concentration difference in the vertical section of wind direction with the wind speed. The calculation process is expressed as: ， In the formula, is the emission flux of the emission source; is the integrated height of the plane perpendicular to the wind direction; is the integrated width of the plane perpendicular to the wind direction; is the wind speed vertical to the aerial survey plane; is the CH4 concentration signal enhancement value, is the CH4 concentration signal value measured by the drone, is the background methane concentration value, is the emission flux of the lower profile, is the emission flux of the upper profile; Multiple groups of up and down wind direction profiles were taken for repeated calculation and averaged to verify the consistency and reliability of the flux calculation results between the UAV platform and the satellite platform.

9. A landfill methane emission flux measurement device, characterized in that: The device comprises: A signal evaluation module is configured to perform a qualitative analysis on the annual average methane emission signal of the landfill based on regional satellite TROPOMI observation data, and determine the target landfill according to the qualitative analysis results; A first flux calculation module is configured to quantitatively calculate the methane emission flux of the target landfill based on the satellite-borne hyperspectral imager data, and determine the location of the methane emission hotspot area inside the target landfill; The second flux measurement module is configured to locate the emission source inside the target landfill through the active methane laser detection lens carried by the UAV platform, and independently calculate the methane emission flux of the target landfill using the upper and lower profile method. 10 . A non-transitory computer-readable storage medium storing instructions, which, when executed by a processor, perform the method according to claim 1 .

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