Presumption method

Abstract

To improve the accuracy of estimating the amount of gas emitted from the object being measured. [Solution] In this disclosure, the gas concentration is measured at a predetermined measurement height on the object to be measured, and the amount of gas released from the object to be measured is estimated from the measured gas concentration based on a predetermined correlation between the amount of gas released from the object to be measured and the gas concentration at the predetermined measurement height.

Description

Technical Field

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[0001] The present disclosure relates to an estimation method.

Background Art

[0002] [[ID=)12]]The gas concentration flux measuring device of Patent Document 1 includes a laser light source, a laser output control device, a wavelength modulation control device, a first light receiving device, a first direct current component detector, a first wavelength modulation demodulator, an optical system, a reference cell, a second light receiving device, a second direct current component detector, a second wavelength modulation demodulator, a third wavelength modulation demodulator, an analysis device, an adder, a temperature measuring means, a pressure measuring means, and a flow velocity measuring means that directly measures the horizontal two-directional flow velocity components and the vertical flow velocity component of the gas flow in the measurement region and outputs these measurement signals to the analysis device. In the gas concentration flux measuring device of Patent Document 1, the analysis device performs analysis based on the eddy correlation rule using the signal input from the flow velocity measuring means, and calculates the momentum flux and concentration of the gas to be measured using the analysis result.

[0003] Non-Patent Document 1 and Non-Patent Document 2 disclose a method for estimating the amount of methane generated from paddy fields using a laser methane detector. In the methods of Non-Patent Document 1 and Non-Patent Document 2, for example, two laser methane detectors are used to measure the methane concentration at two locations with different altitudes, and the gradient method is used to estimate the amount of methane generated from the paddy fields.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Non-Patent Documents

[0005]

Non-Patent Document 1

[0006] In contrast, the prior art described in Non-Patent Documents 1 and 2 does not provide an estimate of the actual amount of methane produced and the methane concentration. Therefore, it is not possible to verify the accuracy of the estimate, and there are issues with the estimation accuracy.

[0007] This disclosure aims to improve the accuracy of estimating the amount of gas emitted from the object being measured. [Means for solving the problem]

[0008] In the first embodiment, the gas concentration is measured at a predetermined measurement height on the object to be measured, and the amount of gas released from the object to be measured is estimated from the measured gas concentration based on a predetermined correlation between the amount of gas released from the object to be measured and the gas concentration at the predetermined measurement height.

[0009] Thus, in the first embodiment, the amount of gas emitted is estimated from the gas concentration measured at the target of measurement based on a pre-determined correlation, making it possible to improve the accuracy of estimating the amount of gas emitted from the target of measurement compared to the conventional technology.

[0010] In the second embodiment, in the first embodiment, a test gas is released in a predetermined amount under conditions that simulate the environment of the object to be measured, the gas concentration of the test gas is measured at the predetermined measurement height, and the correlation is determined.

[0011] Thus, in the second embodiment, a test gas is released in a predetermined amount under conditions that simulate the environment of the object being measured, and the gas concentration is measured at a predetermined measurement height to determine the correlation. As a result, data showing a highly accurate correlation can be obtained.

[0012] In the third embodiment, as in the second embodiment, the gas concentration of the test gas at the predetermined measurement height is measured until it reaches a steady state, and the correlation is determined.

[0013] Thus, in the third embodiment, the gas concentration of the test gas at a predetermined measurement height is measured until it reaches a steady state, so that data showing a highly accurate correlation can be obtained. As a result, the accuracy of estimating the amount of gas emitted from the measurement target can be improved.

[0014] In the fourth embodiment, a test gas is released from below a cylindrical body with an open top, according to the second embodiment, in a predetermined amount, and the gas concentration of the test gas is measured at the predetermined measurement height to determine the correlation.

[0015] Thus, in the fourth embodiment, a test gas at a preset rate is released from the bottom of a cylindrical body with an open top, creating an environment that closely resembles the environment of the object being measured. As a result, data showing a highly accurate correlation can be obtained. Consequently, the accuracy of estimating the amount of gas released from the object being measured can be improved.

[0016] In the fifth embodiment, as in the fourth embodiment, a predetermined amount of test gas is released through a dispersion unit provided at the lower part of the cylindrical body for dispersing the test gas.

[0017] Thus, in the fifth embodiment, a predetermined amount of test gas is released through a dispersion unit that disperses the test gas, creating an environment that approximates the environment of the object being measured. As a result, data showing a highly accurate correlation can be obtained. Consequently, the accuracy of estimating the amount of gas released from the object being measured can be improved.

[0018] In the sixth aspect, in the fourth aspect, the cylindrical body has a height equal to or greater than the predetermined measurement height, and is formed of a material that transmits a laser that is absorbed by the test gas. The laser is irradiated at the predetermined measurement height so that the laser passes through the cylindrical body from the outside of the cylindrical body, and the gas concentration of the test gas is measured.

[0019] Thus, in the sixth aspect, since the cylindrical body has a height equal to or greater than the predetermined measurement height, an environment approximating the environment of the measurement target can be created. Further, the laser is irradiated at the predetermined measurement height so that the laser passes through the cylindrical body from the outside of the cylindrical body, and the gas concentration of the test gas is measured. For this reason, data showing a highly accurate correlation can be obtained. As a result, the estimation accuracy of the gas emission amount from the measurement target can be improved.

Advantages of the Invention

[0020] Since the present disclosure has the above-described configuration, the estimation accuracy of the gas emission amount from the measurement target can be improved.

Brief Description of the Drawings

[0021] [Figure 1] It is a schematic diagram showing an example of the measuring device according to the present embodiment. [Figure 2] It is a schematic diagram showing an example of the test device according to the present embodiment. [Figure 3] It is a block diagram showing an example of the processing device according to the present embodiment. [Figure 4] It is a block diagram showing an example of the functional configuration of the processor in the processing device according to the present embodiment. [Figure 5] It is a graph showing the correlation according to the present embodiment.

Embodiments for Carrying Out the Invention

[0023] <Method for estimating gas emission amount> The method for estimating the amount of gas released according to this embodiment will be described below.

[0024] The method for estimating the amount of gas released according to this embodiment, as shown in Figure 1, involves measuring the gas concentration at a predetermined measurement height H on the measurement target 100, and estimating the amount of gas released from the measurement target 100 from the measured gas concentration based on a pre-determined correlation between the amount of gas released from the measurement target 100 and the gas concentration at the predetermined measurement height H. The measurement target 100, gas 110, specific estimation method, effects of this embodiment, and modified examples will be described below.

[0025] <Measurement target 100> The measurement target 100 is the object whose gas concentration is measured. The measurement target 100 can be, for example, the ground or water surface that emits gas 110. In other words, the measurement target 100 can be, for example, an object that has an upward-facing surface and emits gas into an open space upward from that surface. Specifically, examples of measurement targets 100 include rice paddies and landfills. However, the measurement targets in this disclosure are not limited to those mentioned above; any object that emits gas can be the measurement target.

[0026] <Gas 110> Gas 110 is a gas emitted from the object to be measured 100, and its concentration is measured at a predetermined measurement height H within the object to be measured 100. Examples of gas 110 include greenhouse gases. Examples of greenhouse gases include methane gas. However, the gases of this disclosure are not limited to those mentioned above, and any gas emitted from the object to be measured that can be measured is applicable.

[0027] <Specific estimation method> The estimation method specifically comprises a preparation step, a measurement step, and an estimation step. Each step will be described below.

[0028] <Preparation process> In the preparation step, the correlation (hereinafter sometimes referred to as correlation S) between the amount of gas released from the measurement target 100 and the gas concentration at a predetermined measurement height H is determined in advance. In this embodiment, for example, the correlation S is determined using the test apparatus 20 shown in Figure 2.

[0029] The test apparatus 20 includes a discharge device 21 for releasing a test gas and a measuring device 30 for measuring the gas concentration of the test gas. The test gas used has the same components as gas 110. Therefore, if the type of gas 110 released from the object to be measured 100 changes, the test gas will also change accordingly.

[0030] The discharge device 21 discharges a preset amount of test gas under conditions that simulate the environment of the measurement target 100. Specifically, the discharge device 21 includes a cylindrical body 22, a dispersion unit 28, a gas discharge unit 23, and a flow meter 26.

[0031] The cylindrical body 22 is formed in a cylindrical shape (for example, a cylindrical shape) with both ends in the axial direction open. The cylindrical body 22 is positioned with the vertical direction as its axial direction. The cylindrical body 22 has a height of at least a predetermined measurement height H.

[0032] The cylindrical body 22 is made of a transparent material that transmits the laser from the measuring device 30. The transparent material used has a transmittance of, for example, 90% or more. Specific examples of transparent materials include acrylic and glass. A reflective material 27 that reflects the laser from the measuring device 30 is attached to the inner wall of the cylindrical body 22. This reflective material 27 is positioned along the axial direction on a portion of the circumferential direction of the cylindrical body 22. The reflective material 27 has a reflective surface 27A facing the inner circumference (radially inward) of the cylindrical body 22.

[0033] The internal space of the cylindrical body 22 is closed on the sides by side walls 22A arranged around the axial direction of the cylindrical body 22, and is open at the top.

[0034] The gas discharge section 23 discharges test gas into the cylindrical body 22 from below. Specifically, the gas discharge section 23 has a containment section 24 for containing the test gas and a connecting section 25 for connecting the containment section 24 and the cylindrical body 22.

[0035] The containment section 24 is, for example, composed of a gas cylinder and contains compressed test gas. The containment section 24 has an outlet 24A for releasing the test gas inside, and an on / off valve 24B is provided at the outlet 24A.

[0036] The connecting portion 25 is, for example, a connecting pipe that connects the housing portion 24 and the cylindrical body 22. One end of the connecting portion 25 is connected to the discharge port 24A via the on / off valve 24B of the housing portion 24. The other end of the connecting portion 25 is connected to the lower end of the cylindrical body 22.

[0037] The flow meter 26 is installed in the connection section 25 and measures the flow rate of the gas released from the containment section 24 to the cylindrical body 22. In the gas discharge section 23, a preset amount of test gas is released by adjusting the opening of the on-off valve 24B based on the flow meter 26.

[0038] The dispersion section 28 has the function of dispersing the test gas released from the connection section 25 into the cylindrical body 22. The dispersion section 28 is located at the bottom of the cylindrical body 22. In the discharge device 21, the test gas from the gas discharge section 23 is released into the interior of the cylindrical body 22 via the dispersion section 28. Specifically, the dispersion section 28 is attached to the lower end inside the cylindrical body 22 so as to close the lower opening of the cylindrical body 22. The dispersion section 28 is made of a porous material such as a sponge. When a porous material is used as the dispersion section 28, materials with different opening ratios and pore diameters may be stacked in the axial direction of the cylindrical body 22.

[0039] The measuring device 30 is a device for measuring the gas concentration of a test gas released into the cylindrical body 22 at a predetermined measuring height H. The measuring device 30 includes, for example, an irradiation unit 31, a light receiving unit 32, and a processing device 40.

[0040] The irradiating unit 31 and the light-receiving unit 32 are provided on the outer circumference of the cylindrical body 22, facing the reflective surface 27A of the reflecting material 27. The irradiating unit 31 and the light-receiving unit 32 are positioned at a predetermined measurement height H.

[0041] The irradiation unit 31 irradiates the cylindrical body 22 from the outside of the cylindrical body 22 at a predetermined measurement height H so that the laser passes through the cylindrical body 22. Specifically, the irradiation unit 31 irradiates the cylindrical body 22 radially (for example, horizontally) toward the reflective surface 27A of the reflective material 27. In this embodiment, the irradiation unit 31 irradiates with a laser having a wavelength in the region in which absorption by the test gas occurs.

[0042] For example, in the case of methane, the optical absorption spectrum shows relatively high absorption rates around wavelengths of approximately 1.6 μm and 3.3 μm in the infrared region, within the wavelength range of 1 μm to 5 μm. When methane is used as the test gas, the irradiation unit 31 can be configured to irradiate with a laser having a wavelength of approximately 1.6 μm or 3.3 μm, as an example.

[0043] The laser emitted from the irradiation unit 31 passes through the side wall of the cylindrical body 22 and the internal space of the cylindrical body 22 in that order, is reflected by the reflector 22R, passes through the internal space of the cylindrical body 22 and the side wall of the cylindrical body 22 in that order, and reaches the light receiving unit 32. The measuring device 30 then measures the gas concentration based on the light intensity received by the light receiving unit 32. The measuring device 30 continues measuring until the gas concentration of the test gas at a predetermined measurement height H reaches a steady state.

[0044] The irradiation unit 31 and the light receiving unit 32 may be arranged at multiple heights, each with a predetermined measurement height H, as shown in Figure 2.

[0045] Here, the processing unit 40 has the functionality of a computer and, as shown in Figure 3, includes a processor 41, memory 42, storage 43, input unit 44, communication unit 45, and display unit 46.

[0046] For example, a general-purpose processor such as a CPU (Central Processing Unit) can be used as the processor 41. Alternatively, the processor 41 may be a dedicated processor composed of circuits specifically designed to perform a particular task. Furthermore, the processor 41 is not limited to a single processor, but may consist of multiple processors physically separated from each other.

[0047] Storage 43 stores various programs and various data. Specifically, storage 43 is implemented by recording devices such as HDDs (Hard Disk Drives), SSDs (Solid State Drives), and flash memory.

[0048] Memory 42 is a workspace for the processor 41 to execute various programs, and it temporarily stores various programs or data when the processor 41 is executing processing. The processor 41 reads various programs from storage 43 into memory 42 and executes the programs using memory 42 as a workspace.

[0049] The input unit 44 is a component into which various information and instructions are input by the user. Specifically, the input unit 44 is composed of, for example, a pointing device such as a mouse and input keys such as a keyboard.

[0050] The input unit 44 is not limited to a pointing device and input keys, but may also consist of a touch panel or the like, as long as it is capable of receiving various types of information and instructions.

[0051] The communication unit 45 is a connection unit (communication interface) for communicating with other devices. Specifically, the communication unit 45 communicates with other devices through a communication line using at least one of wired and wireless communication.

[0052] The display unit 46 notifies the user of the information to be presented by displaying the information to be presented to the user. This display unit 46 is composed of, for example, a liquid crystal display and an organic EL (Electro Luminescence) display.

[0053] The processing unit 40 acquires concentration data indicating the gas concentration measured by the measuring device 30. Based on the concentration data, the processing unit 40 pre-determines the correlation S between the amount of gas released from the measurement target 100 and the gas concentration at a predetermined measurement height H. The processing unit 40 stores the correlation data indicating this correlation S in the storage device 34.

[0054] In the processing unit 40, the processor 41 executes the processing program 43A to realize various functions. The functional configuration realized through the cooperation of the processor 41 as a hardware resource and the processing program 43A as a software resource will be described below. Figure 4 is a block diagram showing the functional configuration of the processor 41.

[0055] As shown in Figure 4, in the processing unit 40, the processor 41 functions as an acquisition unit 41A and a processing unit 41B by executing the processing program 43A.

[0056] The acquisition unit 41A acquires concentration data indicating the gas concentration measured by the measuring device 30. Based on the concentration data, the processing unit 41B pre-determines the correlation S between the amount of gas released from the measurement target 100 and the gas concentration at a predetermined measurement height H. For example, correlation data showing the correlation S as shown in Figure 5 is obtained. The processing unit 41B stores the correlation data showing the correlation S in the storage unit 43.

[0057] <Measurement Process> The measurement process involves measuring the gas concentration at a predetermined measurement height H on the object to be measured 100. In the measurement process, the gas concentration is measured using a measuring device 50. As shown in Figure 1, the measuring device 50 includes a laser irradiation unit 14, a laser light receiving unit 16, and a processing unit 19.

[0058] The predetermined measurement height H is set, for example, at a position higher than any obstacles on the measurement target 100 that obstruct laser irradiation, and close to the surface of the measurement target 100 from which the gas 110 is emitted. If the measurement target 100 is a paddy field, for example, the predetermined measurement height H is set at a position higher than the rice plants acting as obstacles, and close to the surface of the paddy field. If the measurement target 100 is a paddy field, the measurement height H may be changed or multiple measurement heights H may be set depending on the presence or absence of rice plants and the growth of the rice plants.

[0059] <Laser irradiation section 14> The laser irradiation unit 14 has the function of irradiating a measurement laser. Specifically, the laser irradiation unit 14 irradiates a laser into the space above the object to be measured 100 at a predetermined measurement height H. In this embodiment, the laser irradiation unit 14 irradiates a detection laser with a wavelength corresponding to the optical absorption spectrum of the gas to be irradiated.

[0060] For example, in the case of methane, the optical absorption spectrum shows relatively high absorption rates around wavelengths of approximately 1.6 μm and 3.3 μm in the infrared region, within the wavelength range of 1 μm to 5 μm. Therefore, when the gas to be measured is methane, the irradiation unit 31 can be configured to irradiate with a laser having a wavelength of approximately 1.6 μm or 3.3 μm, as an example.

[0061] Thus, the laser irradiation unit 14 irradiates with a detection laser of a wavelength corresponding to the optical absorption spectrum of the gas to be measured. Therefore, when a gas other than methane is used as the measurement target 100, the unit is configured to irradiate with a measurement laser of a wavelength with a relatively high absorption rate in the optical absorption spectrum of that gas.

[0062] <Laser light receiving unit 16, processing unit 19> The laser receiving unit 16 shown in Figure 2 receives the reflected light reflected by the reflector 18. The processing unit 19 calculates the total amount of methane between the laser irradiation unit 14 and the reflector 18 based on the laser intensity of the measurement laser received by the laser receiving unit 16. Specifically, the processing unit 19 calculates the gas concentration (ppm) based on the laser intensity.

[0063] The processing unit 19 is configured with a control unit (control board) which includes a recording unit consisting of a storage device on which the program is recorded, and a processor that operates according to the program. The processing unit 19 transmits the calculated gas concentration data to the processing unit 40.

[0064] <Estimated process> The estimation process is a process of estimating the amount of gas released from the measurement target 100 from the measured gas concentration, based on a predetermined correlation S between the amount of gas released from the measurement target 100 and the gas concentration at a predetermined measurement height H. In the estimation process, the processing device 40 estimates the amount of gas released based on the gas concentration measured by the measuring device 50 in the measurement process.

[0065] As shown in the figure, in the processing unit 40, the processor 41 functions as an acquisition unit 41A and an estimation unit 41C by executing the estimation program 43B.

[0066] The acquisition unit 41A acquires concentration data indicating the gas concentration measured by the measuring device 50. The estimation unit 41C estimates the amount of gas released from the measurement target 100 based on the concentration data, using the correlation S between the amount of gas released from the measurement target 100 and the gas concentration at a predetermined measurement height H.

[0067] The display unit 46 displays the gas emission amount estimated by the estimation unit 41C. This presents the estimation results from the processing device 40 to the outside (specifically, the user).

[0068] <Effects and Effects According to This Embodiment> According to this embodiment, the gas concentration is measured at a predetermined measurement height H in the object to be measured 100, and the amount of gas released from the object to be measured 100 is estimated from the measured gas concentration based on a predetermined correlation S between the amount of gas released from the object to be measured 100 and the gas concentration at the predetermined measurement height H.

[0069] Thus, in this embodiment, the amount of gas released is estimated from the gas concentration measured at the measurement target 100 based on a predetermined correlation S, thereby improving the accuracy of estimating the amount of gas released from the measurement target 100 compared to the conventional technology.

[0070] Furthermore, in this embodiment, a test gas is released in a predetermined amount under conditions that simulate the environment of the measurement target 100, the gas concentration of the test gas is measured at the predetermined measurement height, and the correlation S is determined. As a result, data showing a highly accurate correlation S can be obtained. This improves the accuracy of estimating the amount of gas released from the measurement target 100.

[0071] Furthermore, in this embodiment, the gas concentration of the test gas at a predetermined measurement height H is measured until it reaches a steady state. Therefore, data showing a highly accurate correlation S can be obtained. As a result, the accuracy of estimating the amount of gas emitted from the measurement target 100 can be improved.

[0072] Furthermore, in this embodiment, a test gas at a preset gas release rate is released from below the cylindrical body 22, which has an open top, and the gas concentration of the test gas is measured at a predetermined measurement height H. This makes it possible to create an environment that approximates the environment of the measurement target 100. As a result, data showing a highly accurate correlation S can be obtained. Consequently, the accuracy of estimating the amount of gas released from the measurement target 100 can be improved.

[0073] Furthermore, in this embodiment, a predetermined amount of test gas is released through a dispersion unit that disperses the test gas, and the gas concentration of the test gas is measured at a predetermined measurement height H. This makes it possible to create an environment that approximates the environment of the measurement target 100. As a result, data showing a highly accurate correlation S can be obtained. Consequently, the accuracy of estimating the amount of gas released from the measurement target 100 can be improved.

[0074] Furthermore, in this embodiment, since the cylindrical body 22 has a height of at least a predetermined measurement height H, an environment approximating the environment of the measurement target 100 can be created. In addition, the laser is irradiated from the outside of the cylindrical body 22 at a predetermined measurement height H so that the laser passes through the cylindrical body 22, and the gas concentration of the test gas is measured. As a result, data showing a highly accurate correlation S can be obtained. As a result, the accuracy of estimating the amount of gas emitted from the measurement target 100 can be improved.

[0075] <Variation> In this embodiment, the correlation S was determined using the test apparatus 20, but this is not limited to this. For example, the correlation S may be determined based on the measurement results of the actual measurement target 100. Furthermore, the configuration of the test apparatus 20 is not limited to the one described above, and various forms can be applied.

[0076] The present invention is not limited to the embodiments described above, and various modifications, changes, and improvements are possible without departing from the spirit of the invention. For example, the modified forms shown above may be combined in any way.

[0077] <Note> [Aspect 1] The gas concentration is measured at a predetermined measurement height at the target of measurement. Based on a predetermined correlation between the amount of gas emitted from the object being measured and the gas concentration at the predetermined measurement height, the amount of gas emitted from the object being measured is estimated from the measured gas concentration. Estimation method. [Aspect 2] Under conditions that simulate the environment of the object to be measured, a test gas is released at a predetermined gas release rate. The gas concentration of the test gas is measured at the predetermined measurement height. The correlation is determined The estimation method described in Embodiment 1. [Aspect 3] The gas concentration of the test gas at the predetermined measurement height is measured until it reaches a steady state. The correlation is determined The estimation method described in Embodiment 2. [Aspect 4] A test gas is released from the bottom of a cylindrical body with an open top, at a predetermined rate. The gas concentration of the test gas is measured at the predetermined measurement height. The correlation is determined The estimation method described in Embodiment 2 or Embodiment 3. [Aspect 5] A predetermined amount of test gas is released through a dispersion unit located at the lower part of the cylindrical body, which disperses the test gas. The estimation method described in Embodiment 4. [Aspect 6] The cylindrical body has a height greater than or equal to the predetermined measurement height and is made of a material that transmits the laser that is absorbed by the test gas. The laser is irradiated from the outside of the cylindrical body at a predetermined measurement height so that the laser passes through the cylindrical body, and the gas concentration of the test gas is measured. The estimation method described in Embodiment 4 or Embodiment 5. [Explanation of Symbols]

[0078] 14 Laser irradiation area 16 Laser light receiving section 18 Reflector 19 Processing Unit 20 Test equipment 21 Release device 22 Cylinder 22A side wall 22R reflective material 23 Gas discharge section 24 Storage Unit 24A outlet 24B Shut-off valve 25 Connection part 26 Flow meter 27 Reflective material 27A reflective surface 28 Dispersion section 30 Measuring devices 31 Irradiation area 32 Light receiving section 34 Storage device 40 Processing Unit 41 processors 41A Acquisition Department 41B Processing Unit 41C Estimation part 42 memory 43 Storage 43A Processing Program 43B Estimation Program 44 Input section 45 Communications Department 46 Display section 50 Measuring devices 100 items to be measured 110 Gas

Claims

1. The gas concentration is measured at a predetermined measurement height at the target of measurement. Based on a predetermined correlation between the amount of gas emitted from the object being measured and the gas concentration at the predetermined measurement height, the amount of gas emitted from the object being measured is estimated from the measured gas concentration. Estimation method.

2. Under conditions that simulate the environment of the object to be measured, a test gas is released at a predetermined gas release rate. The gas concentration of the test gas is measured at the predetermined measurement height. The correlation is determined The estimation method according to claim 1.

3. The gas concentration of the test gas at the predetermined measurement height is measured until it reaches a steady state. The correlation is determined The estimation method according to claim 2.

4. A test gas is released from the bottom of a cylindrical body with an open top, at a predetermined rate. The gas concentration of the test gas is measured at the predetermined measurement height. The correlation is determined The estimation method according to claim 3.

5. A predetermined amount of test gas is released through a dispersion unit located at the lower part of the cylindrical body, which disperses the test gas. The estimation method according to claim 4.

6. The cylindrical body has a height greater than or equal to the predetermined measurement height and is made of a material that transmits the laser that is absorbed by the test gas. The laser is irradiated from the outside of the cylindrical body at a predetermined measurement height so that the laser passes through the cylindrical body, and the gas concentration of the test gas is measured. The estimation method according to claim 4.

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