Landfill Methane Emission Flux Measurement Method, Device and Medium

Abstract

The present invention relates to the field of remote sensing monitoring of landfill methane emissions, and discloses a method, device and medium for calculating the methane emission flux of landfills. The method includes: based on regional satellite TROPOMI observation data, qualitatively analyzing the annual average methane emission signal of the landfill, and determining the target landfill according to the qualitative analysis results; quantitatively calculating the methane emission flux of the target landfill and determining the location of the methane emission hot spot area inside the target landfill based on the spaceborne hyperspectral imager data; positioning the location of the emission source inside the target landfill through an active methane laser detection lens carried by a drone platform, and independently calculating the methane emission flux of the target landfill by using the up-and-down profile method. Based on this method, the present invention can relatively quickly and accurately evaluate the annual average methane emission situation of landfills, obtain the methane emission flux of the entire landfill and locate the methane emission hot spot area inside the landfill.

Description

Technical Field

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

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

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

[0004] In recent years, there has also been a part of the technology that uses drones equipped with active methane laser detection lenses to conduct top-down qualitative detection of landfill methane. For example, in the patent technical literature with the application number CN202210671233.9, a landfill methane flux measurement device and method based on air-ground dual-field coupling are provided. Generally speaking, the advantages of the drone platform include high spatial resolution of the obtained 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 internal leakage positions of landfills. However, its limitations are also relatively obvious, including limited monitoring range and difficulty in covering large-area landfills; being sensitive to weather conditions, and wind speed, humidity, etc. will affect the measurement accuracy; high operation cost and difficulty in realizing large-scale long-term monitoring.

[0005] In contrast, methane inversion technology based on satellite observations has the ability to comprehensively cover landfills. It can not only accurately locate methane emission hotspots but also support large-scale, long-term, and multi-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 globally. It provides an efficient and reliable solution for the comprehensive assessment of landfill methane emissions and shows great potential especially in global-scale applications.

[0006] Currently, spaceborne detection satellites can be divided into two categories: regional emission flux detection satellites and point-source hyperspectral imagers. A typical example of a regional emission satellite is TROPOMI. TROPOMI features excellent global coverage and a short revisit cycle, enabling daily global coverage. However, its resolution is relatively low (about 5 km) and the detection lower limit of methane emission flux is relatively high (about 5 t / h). Therefore, TROPOMI is suitable for inverting the total methane emission flux of a region but difficult to distinguish the emission signals of different methane emission sources within the region. Especially in urban areas where municipal landfills are located, the surface characteristics are complex, the background noise is high, and there are many potential emission sources. Currently, TROPOMI can only directly distinguish and capture the emission signals of dozens of the largest municipal solid waste landfills globally.

[0007] The other type of spaceborne point-source hyperspectral imager (such as EMIT, PRISMA, EnMAP, etc.) has a higher spatial resolution (30m / 60m) and a lower flux detection lower limit (~500 kg / h), and can image and quantify methane emission plumes at the facility scale within large emission sources (such as oil and gas factories, coal mine ventilation shafts, large municipal solid waste landfills). However, the revisit cycle of this type of instrument is relatively long (usually about one month), and it is affected by clouds in actual observations, resulting in fewer successful observations available for methane inversion. Therefore, it is difficult to comprehensively evaluate the dynamic changes of annual methane emissions from landfills. Summary of the Invention

[0008] The present invention proposes a method, device, and medium for calculating the methane emission flux of landfills, aiming to combine the respective advantages of regional satellites, spaceborne point-source hyperspectral imagers, unmanned aerial vehicles, ground monitoring, and other platforms in detecting landfill methane emissions, solve the existing problems in the current landfill methane emission signal evaluation technology of each single remote sensing platform, and provide technical support for methane control and emission reduction in municipal solid waste landfills.

[0009] According to the first aspect of the present invention, there is provided a method for calculating the methane emission flux of landfills, the method comprising:

[0010] Based on the regional satellite TROPOMI observation data, qualitatively analyze the annual average methane emission signal of the landfill, and determine the target landfill according to the results of the qualitative analysis;

[0011] Based on the spaceborne hyperspectral imager data, quantitatively measure the methane emission flux of the target landfill, and determine the location of the methane emission hot spot area inside the target landfill;

[0012] Through the active methane laser detection lens carried by the UAV platform, locate the emission source position inside the target landfill, and independently calculate the methane emission flux of the target landfill by using the up and down profile method.

[0013] Furthermore, based on the regional satellite TROPOMI observation data, qualitatively analyze the annual average methane emission signal of the landfill, and determine the target landfill, specifically including:

[0014] Obtain the TROPOMI observation data and preprocess the TROPOMI observation data;

[0015] Based on the angle between the actual wind direction on the day and the due north direction, rotate the corresponding angle, and perform a two-dimensional coordinate transformation on the preprocessed TROPOMI observation data. After the transformation, the plume emission signal of the landfill always faces the due north direction; among them, the calculation formula for performing a two-dimensional coordinate transformation on the preprocessed TROPOMI observation data is:

[0016] ,

[0017] In the formula, and are the longitude and latitude abscissa values and ordinate values before the wind direction rotation transformation respectively, and are the longitude and latitude abscissa values and ordinate values after the wind direction rotation transformation respectively, and are the longitude and latitude abscissa values and ordinate values of the landfill respectively, is the angle between the actual wind direction on the day and the due north direction;

[0018] Perform spatial overlapping area oversampling processing on the TROPOMI observation data before and after the wind direction rotation respectively, and obtain the annual average methane concentration increment map of the landfill area;

[0019] Based on the annual average methane concentration increment map of the landfill area, use the mass balance method to quantitatively evaluate the methane emission signal of the landfill;

[0020] Based on the results of spatial overlap area oversampling and wind direction rotation, determine whether there is methane emission in the landfill. In the case of methane emission, use the landfill as the target landfill.

[0021] Furthermore, perform spatial overlap area oversampling on the TROPOMI observation data before and after wind direction rotation respectively to obtain the annual average methane concentration increment map of the landfill area, specifically including:

[0022] Set up a grid centered on the longitude and latitude coordinates of the landfill; among them, the grid includes multiple grids;

[0023] Perform weighted averaging of the rotated TROPOMI daily observation data over the year on the grid; among them, the average weight uses the ratio of the actual overlapping area of the satellite's daily actual observed pixels to the preset pixels; traverse all grid points to obtain the annual average methane concentration increment map of the landfill area.

[0024] Furthermore, based on the spaceborne hyperspectral imager data, quantitatively measure the methane emission flux of the target landfill and determine the location of the methane emission hot spot area inside the target landfill, specifically including:

[0025] Obtain the original radiance data of the spaceborne hyperspectral imager of the target landfill, including remote sensing image data with shortwave infrared bands,

[0026] Calculate the methane unit absorption spectrum k of the set observation scenario in the atmospheric radiative transfer simulation environment according to the actual observation conditions; among them, the actual observation conditions include the satellite sensor altitude, the ground altitude of the target landfill, the solar zenith angle, and the observation azimuth angle;

[0027] Calculate the methane concentration increment of the target landfill according to the original radiance value of each pixel in the whole scene image and the methane unit absorption spectrum k ;

[0028] 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 through the following formula:

[0029] ,

[0030] In the formula, is the methane emission rate, is the effective wind speed of 10 m at the location of the landfill, is the j th pixel area, is the number of pixels within the plume after masking, is the jMethane mass increment within a pixel is the effective length of the plume, specifically defined as the square root of the plume area after masking.

[0031] Furthermore, the methane concentration increment in the target landfill is calculated by the formula:

[0032] ,

[0033] wherein, is the average radiance value of the entire scene image, is the original radiance value of each pixel in the entire scene image, is the covariance matrix of the selected calculation band of the entire scene image, and T represents the transpose of the matrix.

[0034] Furthermore, based on the original radiance value of each pixel in the entire scene image and the methane unit absorption spectrum k, the methane concentration increment in the target landfill is calculated, specifically including:

[0035] The methane concentration increment in the target landfill is calculated separately using the two channels of the weak methane absorption band of 1600 - 1900 nm and the strong methane absorption band of 2150 - 2500 nm in the short-wave infrared band. Taking the covariance value of the radiance values within the two-channel entire scene image range as the weight, the new weighted average methane concentration increment in the target landfill is calculated;

[0036] The methane concentration increment in the target landfill is iterated to further filter and remove background noise; among them, the calculation formula for iterating the methane concentration increment in the target landfill is:

[0037] ,

[0038] wherein, i is the number of iterations, is the simulated background value after removing the methane concentration increment in the target landfill, is the original radiance value of the image.

[0039] Furthermore, through the active methane laser detection lens carried by the UAV platform, the position of the emission source inside the target landfill is located, and the methane emission flux of the target landfill is independently calculated using the up and down profile method, including:

[0040] Using the active methane laser detection lens and the wind speed and direction sensor carried by the UAV, regional inspections are carried out on the position of the hot spot emission area of the target landfill obtained by satellite monitoring to obtain monitoring concentration data; among them, the monitoring concentration data includes methane concentration data and site wind speed and direction data;

[0041] Import the monitored concentration data into a geographic information system, generate a spatial distribution map of the methane concentration on the landfill surface using an interpolation algorithm, identify hotspots with abnormally elevated methane concentrations, and clarify their distribution ranges and locations; combine time series analysis to evaluate the dynamic change trends of the hotspots, and screen out persistent hotspots to locate the specific positions of the methane emission sources inside the landfill;

[0042] According to the spatial distribution map of the methane concentration obtained from the drone inspection, adopt the up and down profile method to calculate the methane emission flux of the hotspot area, and verify the consistency and reliability of the flux calculation results through repeated calculations.

[0043] Furthermore, according to the spatial distribution map of the methane concentration obtained from the drone inspection, adopt the up and down profile method to calculate the methane emission flux of the hotspot area, and verify the consistency and reliability of the flux calculation results through repeated calculations, specifically including:

[0044] Conduct a comparative analysis by combining the satellite and drone concentration distribution monitoring results, divide to obtain the emission source area, and plan multiple profiles in the upwind and downwind areas of the emission source area;

[0045] Based on the concentration difference detected between the upwind and downwind of the emission source, obtain the emission rate of the emission source by integrating the concentration difference in the wind direction vertical profile and the wind speed. The calculation process is expressed as:

[0046] ,

[0047] In the formula, is the emission flux of the emission source; is the integration height of the plane perpendicular to the wind direction; is the integration width of the plane perpendicular to the wind direction; is the wind speed of the vertical aerial survey plane; is the enhanced value of the CH4 concentration signal, 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;

[0048] Take multiple groups of up and down wind profiles for repeated calculations and take the average value to verify the consistency and reliability of the flux calculation results between the drone platform and the satellite platform.

[0049] According to the second aspect of the present invention, there is provided a device for measuring the methane emission flux of a landfill, and the device includes:

[0050] A signal evaluation module, configured to qualitatively analyze 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 result;

[0051] The first flux measurement module is configured to quantitatively measure the methane emission flux of the target landfill based on the spaceborne hyperspectral imager data and determine the location of the methane emission hot spot area inside the target landfill;

[0052] The second flux measurement module is configured to locate the position of the emission source inside the target landfill through an active methane laser detection lens carried by a drone platform and independently calculate the methane emission flux of the target landfill using the up-and-down profile method.

[0053] According to a third aspect of the present invention, there is provided a readable storage medium storing one or more programs, and the one or more programs can be executed by one or more processors to implement the method described above.

[0054] The present invention has at least the following beneficial effects:

[0055] 1. The present invention sacrifices the temporal resolution of TROPOMI observation data in exchange for higher spatial resolution, enabling it to evaluate the methane emission signal of landfill point sources in urban complex background areas.

[0056] 2. Based on the spaceborne hyperspectral imager data, the present invention quantitatively measures the methane emission flux of the target landfill and determines the location of the methane emission hot spot area inside the target landfill, which can more accurately quantitatively measure the overall methane emission rate of the landfill at the moment of satellite overpass and locate the methane emission hot spot 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 background covariance matrix through an iterative process.

[0057] 3. According to the methane emission hot spot area of the target landfill obtained by satellite monitoring, the present invention can further use a drone platform to accurately locate the position of the emission source inside the landfill and independently measure the methane emission flux of the hot spot emission area of the landfill. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Shows a flowchart of a method for measuring the methane emission flux of a landfill according to an embodiment of the present invention.

[0059] Figure 2 Shows a comparison diagram of the wind direction rotation of TROPOMI data of a landfill before and after according to an embodiment of the present invention.

[0060] Figure 3 Shows a schematic diagram of the processing result of directly oversampling the spatial overlap area of the TROPOMI observation signal of the case landfill in 2021 according to an embodiment of the present invention.

[0061] Figure 4 Shows 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; wherein, a is a schematic diagram of the effect of the original matched filtering algorithm; b is a schematic diagram of the effect of the optimized matched filtering algorithm.

[0062] Figure 5 Shows a schematic diagram of the methane concentration distribution result of the landfill measured by the UAV aerial survey according to an embodiment of the present invention.

[0063] Figure 6 Shows a structural diagram of a device for measuring the methane emission flux of a landfill according to an embodiment of the present invention. Detailed implementation manners

[0064] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation manners. The embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, but it is not a limitation to the present invention. For the steps described herein, if there is no necessity for the front-back relationship between them, the order in which they are described as examples herein should not be regarded as a limitation. Those skilled in the art should know that they can be adjusted in order as long as the logic between them is not destroyed and the entire process cannot be realized.

[0065] An embodiment of the present invention provides a method for measuring the methane emission flux of a landfill. As Figure 1 shown, it is a flowchart of this method, and this method includes the following steps S100 to S300, which are introduced in detail as follows:

[0066] S100: Based on the regional satellite TROPOMI observation data, qualitatively analyze the annual average methane emission signal of the landfill, and determine the target landfill according to the qualitative analysis result.

[0067] In step S100, a rapid evaluation and quantification method for the methane emission signal of the landfill for the regional satellite TROPOMI observation data based on the wind direction rotation and spatial overlap area oversampling technology will help to quickly judge the comprehensive methane emission situation of the landfill within a certain time range. If the average methane concentration value near the location of the landfill after the spatial overlap area processing is significantly increased compared with the surrounding background value, and a northward plume signal appears after the wind direction rotation processing, it can prove that there is an obvious methane emission signal in this landfill; then the landfill analyzed qualitatively currently is used as the target landfill to execute the subsequent step S200 and step S300.

[0068] In some embodiments, step S100 includes the following steps S101 to S104.

[0069] S101: Obtain TROPOMI observation data and preprocess the TROPOMI observation data.

[0070] Specifically, in step S101, the original data of each TROPOMI daily observation orbit can be merged and data filtering can be performed according to the quality index QA ≥ 0.4, shortwave infrared (SWIR) aerosol optical thickness < 0.13, and SWIR surface albedo > 0.02. Considering that municipal solid waste landfills are usually located in suburban areas with complex land cover types or valleys with large topographic undulations, compared with the conventional understanding in the art where QA = 1, this relaxed filtering standard can significantly improve the data coverage rate. Only as an example, the way to merge the original data of each TROPOMI daily observation orbit can be to download the original methane column concentration observation products of all observation orbits daily from the Copernicus data center of the European Space Agency and merge the original data of each daily observation orbit.

[0071] S102: Perform wind direction rotation processing on the preprocessed TROPOMI observation data. Calculate the angle between the actual wind direction of the day and the due north direction, rotate the corresponding angle, and perform two-dimensional coordinate transformation on the TROPOMI observation data. So that regardless of the actual wind direction of the day, the plume emission signal of the landfill after transformation always faces the due north direction.

[0072] In this embodiment, the specific calculation formula for performing two-dimensional coordinate transformation on the TROPOMI observation data is as follows:

[0073] ,

[0074] In the formula, and are the longitude and latitude abscissa values before the wind direction rotation transformation and the ordinate value respectively, and are the longitude and latitude abscissa values and the ordinate value after the wind direction rotation transformation respectively, and are the longitude and latitude abscissa values and the ordinate value of the landfill respectively, is the angle between the actual wind direction of the day and the due north direction.

[0075] S103: Perform spatial overlap area oversampling processing on the TROPOMI observation data before and after the wind direction rotation respectively, and obtain the annual average methane concentration increment map of the landfill area with high spatial resolution.

[0076] In some embodiments, step S103 includes the following steps S1031 to S1033.

[0077] S1031: Pre-define a grid centered at the landfill's longitude and latitude coordinates, with a size of 0.5° × 0.5° and a resolution of 0.01°× 0.01°; the grid includes a number of grids.

[0078] S1032: Perform weighted averaging on the rotated TROPOMI daily observation data for a year on a 0.5° × 0.5° grid. The average weight is the ratio of the actual overlapping area of the satellite's daily actual observed pixels to the pre-defined 0.01° × 0.01° pixels in step S1031. Traverse all grids to obtain an annual average methane concentration increment map of the landfill area with a high spatial resolution of 0.01° × 0.01°;

[0079] S1033: Crop the above 0.5° × 0.5° grid to a range centered at the landfill's longitude and latitude coordinates, with a size of 0.25° × 0.25°. The actual length of the landfill methane emission plume is usually within a range of 20 km. Regional cropping can effectively avoid interference from other potential emission sources near the landfill while maintaining the continuity of the image boundary.

[0080] S104: Based on the annual average methane concentration increment map of the landfill area obtained in step S103, use the mass balance method to preliminarily quantitatively evaluate the landfill methane emission signal.

[0081] Exemplarily, as Figures 2 to 3 shown. After performing spatial overlapping area over-sampling processing, Figure 2 it can be observed that the methane concentration value near the center coordinates has a significant increase compared to the surrounding background values. After further performing wind direction rotation processing, Figure 3 it can be clearly observed that there is a methane plume signal towards the due north direction at the marked position of the landfill. Combining the results of spatial overlapping area over-sampling and wind direction rotation, it can be qualitatively determined that there is obvious methane emission from the target landfill.

[0082] It should be noted that currently, the minimum detectable limit for the TROPOMI single-day observation to detect point-source methane emissions is approximately 5 t / h, and the actual methane emission rate values of many small and medium-sized landfills are lower than this detection limit. Even though this method enhances the methane emission signal of the target landfill based on long-term sequence data, generally, this method is only a sufficient but unnecessary condition for judging whether there is obvious methane emission from the landfill. It is necessary to further determine the location of the internal emission hotspots and the specific methane emission rate of the target landfill with satellite-borne hyperspectral and unmanned aerial vehicle platforms with lower detection limits in the future.

[0083] S200: Based on the satellite-borne hyperspectral imager data, quantitatively measure the methane emission flux of the target landfill and determine the location of the internal methane emission hotspots of the target landfill.

[0084] In some embodiments, a scheme of iterative matching filtering for a specific scenario based on hyperspectral data is proposed to perform step S200, thereby enabling a relatively accurate quantitative estimation of the overall methane emission rate of the landfill and locating the methane emission hotspots inside the landfill. This algorithm fully considers the influence of observation conditions (such as solar zenith angle, ground elevation, and sensor operating altitude), and more accurately estimates the background average radiation intensity value and background covariance matrix through an iterative process. Compared with traditional matching filtering algorithms, the proposed scheme of the present invention has significant advantages in retrieving the methane emission plume of the landfill.

[0085] Specifically, step S200 is executed by the following steps S201 to S204.

[0086] S201: Obtain the original radiance data of the spaceborne hyperspectral imager for the target landfill, including but not limited to remote sensing image data with shortwave infrared bands (1000 - 2500 nm) such as (EMIT, PRISMA, EnMap, GF5, GF5B, ZY1 - 02D), etc. The original radiance value of each pixel in the entire scene image is denoted as .

[0087] S202: Calculate the methane unit absorption spectrum k under a specific observation scenario in the atmospheric radiation transfer simulation software modtran according to the actual observation conditions of the specific scenario (including satellite sensor altitude, ground elevation of the target landfill, solar zenith angle, and observation azimuth angle).

[0088] S203: Initially calculate the methane concentration increment of the target landfill (in ppm*m); the specific calculation formula is:

[0089] ,

[0090] wherein, is the average radiance value of the entire scene image, is the original radiance value of each pixel in the entire scene image, is the covariance matrix of the selected calculation band of the entire scene image, and T represents the transpose of the matrix.

[0091] In some embodiments, step S203 includes the following steps S2031 and S2032.

[0092] S2031: Calculate the methane concentration increment of the target landfill Then, using the covariance value of the radiance values within the entire scene images of the two as the weight, calculate the new incremental methane concentration of the target landfill after weighted averaging. 。

[0093] The principle of step S2031 is that the methane strong absorption band of 2150 - 2500 nm has a high absorption sensitivity to methane gas, but the signal-to-noise ratio of the radiation spectrum is low; while the methane weak absorption band of 1600 - 1900 nm has a low absorption sensitivity to methane gas, but the signal-to-noise ratio of the radiation spectrum is high. Under the inversion background of complex surface characteristics, high background noise, and many potential emission sources in the urban area where the domestic landfill is located, dual-channel processing can effectively suppress the background noise of the methane concentration increment map obtained in this step.

[0094] S2032: Iterate on the incremental methane concentration of the target landfill to further filter and remove background noise.

[0095] The principle of step S2032 is that the calculation of the incremental methane concentration of the target landfill according to the least squares method is based on the assumption that the original radiance values of the entire scene image follow a normal distribution under normal circumstances. However, the presence of the methane plume signal near the target landfill will affect the correct estimation of as well as . Therefore, it is necessary to eliminate the influence of potential methane emission sources in the original radiance data, so as to more accurately evaluate as well as . The specific calculation formula is as follows:

[0096] ,

[0097] where i is the number of iterations, and the entire iterative process usually converges after 15 - 30 iterations; is the simulated background value after removing the incremental methane concentration of the target landfill, is the original radiance value of the image.

[0098] S204: Based on the annual average incremental methane concentration map of the target landfill area 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.

[0099] In some embodiments, step S204 includes the following steps S2041 and S2042.

[0100] S2041: Select an 80% confidence interval, perform a student t-test and Gaussian filtering on the incremental methane concentration map of the target landfill obtained in step S203 to obtain the masked methane plume of the target landfill.

[0101] S2042: Estimate the annual average methane emission rate of the target landfill using the mass balance method. The specific calculation formula is as follows:

[0102] ,

[0103] In the formula, is the methane emission rate, is the effective wind speed at 10 m at the location of the landfill, is the j th pixel area (0.01° × 0.01°), is the number of pixels within the plume after masking, is the j th methane mass increment within a pixel, which can be obtained by converting the methane column concentration increment using the ideal gas state equation. is the effective length of the plume, specifically defined as the square root of the area of the plume after masking.

[0104] Exemplarily, Figure 4 is a schematic diagram comparing the effects of inverting methane concentration increments using the original and specific scenario iterative matching filtering algorithms for the EMIT 30 m spatial resolution data of a certain domestic waste landfill (87.85E, 44.04N) on August 18, 2022, provided by an embodiment of the present invention. It can be seen that the inversion result of the specific scenario iterative matching filtering algorithm has less background noise, a smoother gradient descent structure inside the plume, and a more obvious hot spot area range compared to the original matching filtering algorithm. The internal methane hot spot emission area of the landfill can be obtained through visual interpretation as shown in b of Figure 4 to provide key target observation positions for subsequent unmanned aerial vehicle platforms and ground static chambers. Finally, the measured result of the methane emission flux of this landfill on August 18, 2022, is 9.4 ± 0.8 t / h.

[0105] It should be noted that currently, the revisit period of the spaceborne hyperspectral observation platform is relatively long, with an average revisit time of one month. Considering the influence of clouds in actual observations, the possible number of successful observations is even less. Therefore, it is difficult to conduct long-term sequence monitoring of the target landfill. Although actual landfill sites are continuous emission sources, their emission rates are comprehensively affected by atmospheric factors such as humidity, rainfall, temperature, and landfill operation management measures (such as landfill surface covering conditions, landfill waste quantity and composition, and the use of landfill gas collection systems), showing significant dynamic fluctuations. Therefore, the analysis results of TROPOMI data in step S100 and the measurement data of subsequent unmanned aerial vehicle platforms and ground static chambers can be combined to conduct a more comprehensive and integrated assessment of the methane emissions of the target landfill within a certain time range.

[0106] S300: Use the active methane laser detection lens carried by the drone platform to locate the emission source inside the target landfill, and independently calculate the methane emission flux of the target landfill using the up-and-down cross-section method.

[0107] The purpose of step S300 is to further accurately locate the emission source inside the landfill using the drone platform based on the methane emission hotspot area obtained from satellite monitoring, and independently measure the methane emission flux in the hotspot emission area of the landfill.

[0108] In some embodiments, step S300 is implemented by the following steps S301 to S303.

[0109] S301: Data collection. Use the drone to carry an active methane laser detection lens and a wind speed and direction sensor to conduct area inspections on the location of the hotspot emission area of the target landfill obtained from satellite monitoring, and collect methane concentration and site wind speed and direction data.

[0110] S302: Hotspot location. Import the collected monitoring concentration data into the geographic information system, use the interpolation algorithm to generate the spatial distribution map of the methane concentration on the landfill surface, identify the hotspot areas where the methane concentration abnormally increases, and clarify their distribution ranges and locations; combine time series analysis to evaluate the dynamic change trend of the hotspot areas, and screen out the persistent hotspot areas to accurately locate the specific locations of the methane emission sources inside the landfill.

[0111] In some embodiments, step S302 includes the following steps S3021 to S3023.

[0112] S3021: Input the methane concentration data of each discrete point in the methane emission hotspot area collected into the geographic information system, and generate the spatial distribution map of the methane concentration on the landfill surface through the interpolation algorithm (such as ordinary Kriging interpolation);

[0113] S3022: Based on the generated concentration distribution map, use the clustering algorithm to identify the areas where the methane concentration abnormally increases, and clarify the distribution range and specific locations of the hotspots;

[0114] S3023: Combine the time series analysis of the concentration data to evaluate the dynamic change trend of the hotspot areas, and screen out the persistent hotspot areas.

[0115] S303: Flux quantification. According to the methane concentration distribution map obtained from the drone inspection, use the up-and-down cross-section method to calculate the methane emission flux in the hotspot area. Through repeated calculations, verify the consistency and reliability of the flux calculation results.

[0116] In some embodiments, step S303 includes the following steps S3031 to S3033.

[0117] S3031: Conduct a comparative analysis by combining the monitoring results of satellite and drone concentration distributions, and divide to obtain the emission source areas. Plan multiple profiles in the upwind and downwind areas of the emission sources.

[0118] S3032: Based on the detected concentration difference between the upwind and downwind of the emission source, obtain the emission rate of the emission source by integrating the concentration difference in the wind direction vertical profile and the wind speed. The calculation process is expressed as:

[0119] ,

[0120] In the formula, is the emission flux of the emission source, g / s; is the section emission flux, g / s; is the integration height of the plane perpendicular to the wind direction, m; is the integration width of the plane perpendicular to the wind direction, m; is the wind speed of the vertical aerial survey plane, m / s; is the enhanced value of the CH4 concentration signal, ppm. Usually, the upwind test value is used as the background value, and the difference between the downwind test value and the background value is recorded as the enhanced value of the methane concentration signal. is the CH4 concentration signal value measured by the drone, is the background methane concentration value, is the down-section emission flux, is the up-section emission flux.

[0121] S3033: Take multiple groups of upwind and downwind profiles for repeated calculations and take the average value to verify the consistency and reliability of the flux calculation results of the drone platform and the satellite platform.

[0122] Exemplarily, Figure 5 is a schematic diagram of the methane concentration distribution obtained by aerial surveying a certain landfill with a drone equipped with a laser methane detection device. Through dense sampling with the laser methane detection device, high-resolution site methane concentration data is obtained. 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 an obvious aggregation trend in the methane emissions in, and the area where the methane emission source is located can be significantly observed on the right side of the image. After determining the emission source location, static boxes can be arranged on the ground to monitor its methane emission rate and compare and verify it with the quantitative results of the satellite drone and the platform.

[0123] It should be noted that when conducting aerial surveys of landfills using drones equipped with laser methane detection equipment, key factors such as flight planning, equipment calibration, data collection, and post - analysis need to be comprehensively considered. The flight altitude, speed, and flight path overlap need to be reasonably designed. At the same time, attention should be paid to equipment calibration, sampling frequency matching, and the influence of meteorological conditions such as wind speed, wind direction, temperature, and humidity. During the aerial survey, the equipment status should be monitored in real - time, abnormal data should be excluded, and the methane concentration distribution should be visualized using GIS technology, and abnormal areas should be marked to provide a basis for subsequent management and control of methane emissions.

[0124] In some embodiments, after step S300, the landfill methane emission flux measurement method further includes step S400, where ground static chambers and weather stations are arranged in the hot - spot areas inside the landfill obtained from the above - mentioned satellite and drone monitoring platforms to conduct long - term monitoring of the methane emission flux in the hot - spot areas.

[0125] In step S400, the ground weather station can obtain the actual wind speed and wind direction of the site, providing more accurate input parameters for the satellite and drone platforms to invert the methane emission flux of the landfill. At the same time, the weather station can also record important atmospheric factors affecting methane emissions such as atmospheric pressure, humidity, and rainfall. By further analyzing the correlation between the landfill methane emission flux and these atmospheric factors, it can provide a scientific basis and theoretical support for controlling landfill methane emissions.

[0126] An embodiment of the present invention also provides a landfill methane emission flux measurement device, as Figure 6 shown. The device includes:

[0127] A signal evaluation module 601, configured to qualitatively analyze 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 result;

[0128] A first flux measurement module 602, configured to quantitatively measure the methane emission flux of the target landfill based on space - borne hyperspectral imager data, and determine the location of the methane emission hot - spot areas inside the target landfill;

[0129] A second flux measurement module 603, configured to locate the emission source positions inside the target landfill through an active methane laser detection lens carried by a drone platform, and independently calculate the methane emission flux of the target landfill using the up - and - down profile method.

[0130] In some embodiments, the signal evaluation module is further configured to:

[0131] Obtain TROPOMI observation data and pre - process the TROPOMI observation data;

[0132] Based on the angle between the actual wind direction of the day and the due north direction, rotate the corresponding angle, and perform a two-dimensional coordinate transformation on the preprocessed TROPOMI observation data. After the transformation, the plume emission signal of the landfill always faces the due north direction; among them, the calculation formula for performing the two-dimensional coordinate transformation on the preprocessed TROPOMI observation data is:

[0133] ,

[0134] In the formula, and are the longitude and latitude abscissa values and ordinate values before the wind direction rotation transformation respectively, and are the longitude and latitude abscissa values and ordinate values after the wind direction rotation transformation respectively, and are the longitude and latitude abscissa values and ordinate values of the landfill respectively, is the angle between the actual wind direction of the day and the due north direction;

[0135] Perform spatial overlapping area oversampling processing on the TROPOMI observation data before and after the wind direction rotation respectively to obtain the annual average methane concentration increment map of the landfill area;

[0136] Based on the annual average methane concentration increment map of the landfill area, use the mass balance method to quantitatively evaluate the methane emission signal of the landfill;

[0137] According to the results of the spatial overlapping area oversampling and the wind direction rotation, determine whether there is methane emission in the landfill. In the case of methane emission, use the landfill as the target landfill.

[0138] In some embodiments, the signal evaluation module is further configured to:

[0139] Set up a grid centered on the longitude and latitude coordinates of the landfill; among them, the grid includes a plurality of meshes;

[0140] Perform weighted averaging of the rotated TROPOMI daily observation data of a year on the grid; among them, the average weight uses the ratio of the actual overlapping area of the satellite daily actual observation pixels to the preset pixels; traverse all grid points to obtain the annual average methane concentration increment map of the landfill area.

[0141] In some embodiments, the first flux measurement module is further configured to:

[0142] Obtain the original radiance data of the spaceborne hyperspectral imager of the target landfill, including remote sensing image data with shortwave infrared bands,

[0143] Calculate the methane unit absorption spectrum k of the set observation scenario in the atmospheric radiation transfer simulation environment according to the actual observation conditions; wherein, the actual observation conditions include the satellite sensor altitude, the ground altitude of the target landfill, the solar zenith angle, and the observation azimuth angle.

[0144] Calculate the methane concentration increment of the target landfill according to the original radiation brightness value of each pixel in the whole scene image and the methane unit absorption spectrum k. ;

[0145] 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 through the following formula:

[0146] ,

[0147] In the formula, is the methane emission rate, is the effective wind speed of 10m at the location of the landfill, is the j th pixel area, is the number of pixels in the plume after masking, is the j th methane mass increment in the pixel, is the effective length of the plume, specifically defined as the square root of the area of the plume after masking.

[0148] In some embodiments, the methane concentration increment of the target landfill is calculated by the formula:

[0149] ,

[0150] In the formula, is the average radiation brightness value of the whole scene image, is the original radiation brightness value of each pixel in the whole scene image, is the covariance matrix of the selected calculation band of the whole scene image, and T represents the transpose of the matrix.

[0151] In some embodiments, the first flux measurement module is further configured to:

[0152] Calculate the methane concentration increment of the target landfill by using the dual channels of the weak methane absorption band of 1600 - 1900nm and the strong methane absorption band of 2150 - 2500nm in the short-wave infrared band respectively, and calculate the new weighted average methane concentration increment of the target landfill with the covariance value of the radiation brightness values within the range of the dual-channel whole scene image as the weight.

[0153] Iterate the methane concentration increment of the target landfill to further filter and remove background noise. The calculation formula for iterating the methane concentration increment of the target landfill is as follows:

[0154] ,

[0155] In the formula, i is the number of iterations, is the simulated background value after removing the methane concentration increment of the target landfill, is the original radiance value of the image.

[0156] In some embodiments, the second flux measurement module is further configured to:

[0157] Use a drone equipped with an active methane laser detection lens and a wind speed and direction sensor to conduct area inspections on the location of the hot spot emission area of the target landfill obtained by satellite monitoring, and obtain monitoring concentration data. The monitoring concentration data includes methane concentration data and site wind speed and direction data;

[0158] 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 hot spot areas with abnormally increased methane concentration, and clarify their distribution ranges and locations; combine time series analysis to evaluate the dynamic change trend of the hot spot areas, and screen out persistent hot spot areas to locate the specific locations of the methane emission sources inside the landfill;

[0159] According to the spatial distribution map of the methane concentration obtained by drone inspection, use the up and down section method to calculate the methane emission flux of the hot spot area, and verify the consistency and reliability of the flux calculation results through repeated calculations.

[0160] In some embodiments, the second flux measurement module is further configured to:

[0161] Combine the comparison and analysis of the satellite and drone concentration distribution monitoring results, divide the emission source area, and plan multiple sections in the upwind and downwind areas of the emission source area;

[0162] Based on the concentration difference detected in the upwind and downwind directions of the emission source, integrate the concentration difference in the wind direction vertical section and the wind speed to obtain the emission rate of the emission source. The calculation process is expressed as:

[0163] ,

[0164] In the formula, is the emission flux of the emission source; is the integration height of the plane perpendicular to the wind direction; is the integration width of the plane perpendicular to the wind direction; is the wind speed of the vertical aerial survey plane; is the enhanced value of the CH4 concentration signal, is the CH4 concentration signal value measured by the drone, is the background methane concentration value, is the lower-profile emission flux, is the upper-profile emission flux;

[0165] Take multiple sets of upwind and downwind profiles for repeated calculations and take the average value to verify the consistency and reliability of the flux calculation results between the drone platform and the satellite platform.

[0166] It should be noted that the various device structures described in this embodiment belong to the same inventive concept as the method described above, and achieve the same technical effects through the same principle, which will not be elaborated here.

[0167] The embodiment of the present invention also provides a readable storage medium, and the readable storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the method described in any of the above embodiments.

[0168] In addition, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present invention having equivalent elements, modifications, omissions, combinations (e.g., schemes that cross various embodiments), adaptations or changes. The elements in the claims will be broadly interpreted based on the language used in the claims and are not limited to the examples described in this specification or during the implementation of this application, and the examples will be interpreted as non-exclusive. Therefore, this specification and the examples are intended to be considered only as examples, and the true scope and spirit are indicated by the full scope of the following claims and their equivalents.

[0169] The above description is intended to be illustrative rather than restrictive. For example, the above examples (or one or more of their schemes) can be used in combination with each other. For example, those of ordinary skill in the art can use other embodiments when reading the above description. Additionally, in the above specific embodiments, the various features can be grouped together to simplify the present invention. This should not be construed as an intention that the features of an invention not claimed are necessary for any claim. On the contrary, the subject matter of the present invention can be less than all the features of a particular embodiment of the invention. Thus, the following claims are incorporated herein as examples or embodiments into the specific embodiments, where each claim independently serves as a separate embodiment, and considering these embodiments, they can be combined with each other in various combinations or arrangements. The scope of the present invention should be determined with reference to the appended claims and the full scope of the equivalents empowered by these claims.

Claims

1. A method for measuring the methane emission flux of a landfill, characterized in that The method includes: Based on the regional satellite TROPOMI observation data, qualitatively analyze the annual average methane emission signal of the landfill, and determine the target landfill according to the results of the qualitative analysis; Based on the spaceborne hyperspectral imager data, quantitatively measure the methane emission flux of the target landfill and determine the location of the methane emission hotspot area inside the target landfill; Through the active methane laser detection lens carried by the UAV platform, locate the emission source position inside the target landfill, and independently calculate the methane emission flux of the target landfill using the up and down profile method; Based on the regional satellite TROPOMI observation data, qualitatively analyze the annual average methane emission signal of the landfill, and determine the target landfill according to the results of the qualitative analysis, specifically including: Obtain the TROPOMI observation data and preprocess the TROPOMI observation data; Based on the angle between the actual wind direction and the due north direction on the current day, rotate the corresponding angle, and perform two-dimensional coordinate transformation on the preprocessed TROPOMI observation data. After the transformation, the plume emission signal of the landfill always faces the due north direction; among them, the calculation formula for performing two-dimensional coordinate transformation on the preprocessed TROPOMI observation data is: ， In the formula, and are the longitude and latitude abscissa value and ordinate value before the wind direction rotation transformation respectively, and are the longitude and latitude abscissa value and ordinate value after the wind direction rotation transformation respectively, and are the longitude and latitude abscissa value and ordinate value of the landfill respectively, is the angle between the actual wind direction of the day and the due north direction; Perform spatial overlap area oversampling processing on the TROPOMI observation data before and after wind direction rotation respectively to obtain the annual average methane concentration increment map of the landfill area; Based on the annual average methane concentration increment map of the landfill area, use the mass balance method to quantitatively evaluate the methane emission signal of the landfill; According to the results of spatial overlap area oversampling and wind direction rotation, determine whether there is methane emission in the landfill. In the case of methane emission, use the landfill as the target landfill.

2. The method according to claim 1, wherein Perform spatial overlap area oversampling processing on the TROPOMI observation data before and after wind direction rotation respectively to obtain the annual average methane concentration increment map of the landfill area, specifically including: Set a grid centered on the longitude and latitude coordinates of the landfill; among them, the grid includes multiple grids; Perform weighted averaging of the rotated TROPOMI daily observation data over the year on the grid; among them, the average weight is the ratio of the actual overlapping area of the satellite's daily actual observation pixels to the preset pixels; traverse all grid points to obtain the annual average methane concentration increment map of the landfill area.

3. The method according to claim 1, characterized in that, Based on the spaceborne hyperspectral imager data, quantitatively measure the methane emission flux of the target landfill and determine the location of the methane emission hotspot area inside the target landfill, specifically including: Obtain the original radiance data of the spaceborne hyperspectral imager of the target landfill, including remote sensing image data with shortwave infrared bands; Calculate the methane unit absorption spectrum k of the set observation scenario in the atmospheric radiative transfer simulation environment according to the actual observation conditions; among them, the actual observation conditions include the satellite sensor altitude, the ground altitude of the target landfill, the solar zenith angle, and the observation azimuth angle; Calculate the methane concentration increment of the target landfill according to the original radiance value of each pixel in the whole scene image and the methane unit absorption spectrum k ; Based on the incremental methane concentration of the target landfill, determine the annual average incremental methane concentration 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 through the following formula: ， In the formula, is the methane emission rate, is the effective wind speed at 10 m at the location of the landfill, is the j pixel area of the is the number of pixels within the plume after masking, is the j methane mass increment within the is the effective length of the plume, specifically defined as the square root of the area of the plume after masking.

4. The method according to claim 3, wherein Target landfill methane concentration increment The calculation formula is as follows: ， In the formula, is the average radiance value of the entire scene image, is the original radiance value of each pixel in the entire scene image, is the covariance matrix of the selected calculation band of the entire scene image, and T represents the transpose of the matrix.

5. The method according to claim 3 or 4, characterized in that, Calculate the methane concentration increment of the target landfill according to the original radiance value of each pixel in the whole scene image and the methane unit absorption spectrum k , which specifically includes: Use the dual channels of the weak methane absorption band of 1600 - 1900 nm and the strong methane absorption band of 2150 - 2500 nm in the short-wave infrared band to calculate the incremental methane concentration of the target landfill respectively. Take the covariance value of the radiance values within the entire scene image of the dual channels as the weight, and calculate the new incremental methane concentration of the target landfill after weighted average; Iterate the incremental methane concentration of the target landfill to further filter and remove background noise; among them, the calculation formula for iterating the incremental methane concentration of the target landfill is: ， where i is the number of iterations, is the simulated background value after removing the methane concentration increment of the target landfill, is the original radiance value of the image.

6. The method according to claim 1, wherein Through the active methane laser detection lens carried by the UAV platform, locate the position of the emission source inside the target landfill, and independently calculate the methane emission flux of the target landfill using the up and down profile method, including: Use the UAV carrying an active methane laser detection lens and a wind speed and direction sensor to conduct area inspections on the position of the hot spot emission area of the target landfill obtained by satellite monitoring, and obtain monitoring concentration data; among them, the monitoring concentration data includes methane concentration data and site wind speed and direction data; Import the monitoring concentration data into the geographic information system, use the interpolation algorithm to generate the spatial distribution map of the methane concentration on the landfill surface, identify the hot spot areas with abnormally increased methane concentration, and clarify their distribution range and location; combine time series analysis to evaluate the dynamic change trend of the hot spot areas, and screen out the persistent hot spot areas to locate the specific position of the methane emission source inside the landfill; According to the spatial distribution map of the methane concentration obtained by UAV inspection, use the up and down profile method to calculate the methane emission flux of the hot spot area, and verify the consistency and reliability of the flux calculation results through repeated calculations.

7. The method according to claim 6, wherein According to the spatial distribution map of the methane concentration obtained by UAV inspection, use the up and down profile method to calculate the methane emission flux of the hot spot area, and verify the consistency and reliability of the flux calculation results through repeated calculations, specifically including: Combine the satellite and UAV concentration distribution monitoring results for comparative analysis, divide the emission source area, and plan multiple profiles in the upwind and downwind areas of the emission source area; Based on the detected concentration difference between the upwind and downwind of the emission source, integrate the concentration difference in the wind direction vertical profile and the wind speed to obtain the emission rate of the emission source, and the calculation process is expressed as: ， Wherein, is the emission flux of the emission source; is the integration height of the plane perpendicular to the wind direction; is the integration width of the plane perpendicular to the wind direction; is the wind speed of the vertical aerial survey plane; is the enhanced value of the CH4 concentration signal, is the CH4 concentration signal value measured by the UAV, is the background methane concentration value, is the emission flux of the lower profile, is the emission flux of the upper profile; Take multiple groups of up and down wind profiles for repeated calculations and take the average value to verify the consistency and reliability of the flux calculation results between the UAV platform and the satellite platform.

8. A landfill methane emission flux measurement device for implementing the method according to any one of claims 1 to 7, characterized in that, The device includes: A signal evaluation module, configured to qualitatively analyze 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 measurement module, configured to quantitatively measure the methane emission flux of the target landfill based on the spaceborne hyperspectral imager data, and determine the location of the methane emission hot spot area inside the target landfill; The second flux measurement module is configured to locate the position of 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 by using the up-and-down profile method.

9. A non-transitory computer-readable storage medium storing instructions that, when executed by a processor, perform the method according to any one of claims 1 to 7.

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