Geological body radiation energy information extraction method for removing solar radiation effect

Abstract

The invention discloses a geologic body radiation energy information extraction method for removing a solar radiation effect, and relates to the technical field of satellite remote sensing. The vertical radiation flux density of the atmosphere top sun is calculated according to the thermal infrared remote sensing image data, and the direct radiation flux of the earth surface sun is calculated according to the vertical radiation flux density of the atmosphere top sun; calculating to obtain an earth surface albedo; calculating solar radiation energy absorbed by the earth surface according to the earth surface albedo; solar radiation energy absorbed by the earth surface is removed from thermal infrared remote sensing image data of the earth surface in the daytime, and geologic body radiation heat information is obtained through calculation. The remote sensing image is obtained by obtaining the accurate thermal infrared data in the daytime and utilizing the geologic body radiation value algorithm for removing the solar radiation effect, the heat information of the geologic body can be reflected, and the method has very good reference value for searching hidden heat information.

Description

Technical Field

[0001] The invention relates to the field of satellite remote sensing technology, and more specifically, to a method for extracting radiation energy information of a geological body by removing solar radiation effects. Background Art

[0002] Surface temperature is an important indicator for analyzing the earth's environment, and remote sensing technology is an important modern means of earth observation. As a result, more and more studies have been conducted on surface temperature inversion based on remote sensing images. In recent years, with the continuous development of remote sensing technology and the widespread application of satellite remote sensing data, surface temperature inversion from remote sensing satellites has become an important research topic in the field of earth science and environmental monitoring. Surface temperature inversion refers to the process of inferring surface temperature using remote sensing satellite data. Its principle is based on the relationship between the radiation characteristics of the surface of the object and the temperature.

[0003] The inventors conducted surface temperature inversion on thermal infrared data in winter, summer and night, and found that the final results were not ideal. The night data was not obvious because the known hot springs or geothermal fields were next to residential areas or in the shade, and they were medium- and low-temperature hot springs without particularly high temperatures, so the temperature anomalies of hot springs, geothermal wells and geothermal fields were not obvious. The influence of solar radiation still exists at night, so the temperature of water bodies with large thermal inertia and vegetation-covered areas is relatively high, which affects the extraction results.

[0004] Therefore, the present invention aims to provide a method for extracting radiation energy information of geological bodies by removing the solar radiation effect. The method utilizes the abundant thermal infrared data on the earth's surface during the day, removes the solar radiation effect, observes the thermal radiation of geological bodies, and finds abnormal areas therein. Summary of the invention

[0005] The purpose of the present invention is to provide a method for extracting radiation energy information of geological bodies by removing the solar radiation effect. The present invention obtains accurate thermal infrared data during the day and obtains remote sensing images using a geological body radiation value algorithm that removes the solar radiation effect. The remote sensing images can reflect the thermal information of the geological bodies and have a very good reference value for finding hidden heat information.

[0006] The above technical purpose of the present invention is achieved through the following technical scheme: a method for extracting radiation energy information of a geological body by removing the solar radiation effect, comprising the following steps:

[0007] S1. Use satellites to obtain thermal infrared remote sensing image data of the earth's surface during the day, calculate the vertical radiation flux density of the sun at the top of the atmosphere based on the thermal infrared remote sensing image data, and calculate the direct radiation flux of the sun on the surface based on the vertical radiation flux density of the sun at the top of the atmosphere;

[0008] S2, calculate the surface albedo;

[0009] S3, calculate the solar radiation energy absorbed by the surface according to the surface albedo;

[0010] S4. Remove the solar radiation energy absorbed by the surface from the thermal infrared remote sensing image data of the surface during the day, and calculate the radiation heat information of the geological body.

[0011] The present invention is further configured as follows: the calculation formula of the vertical radiation flux density of the sun at the top of the atmosphere in step S1 is:

[0012]

[0013] Among them, I0 is the vertical radiation flux density of the sun at the top of the atmosphere, S0 is the solar constant, and DOY is the Galilean calendar time of remote sensing image formation.

[0014] The calculation formula for the direct solar radiation flux on the earth's surface is:

[0015] I b =I0×τ b ×cos(θ)

[0016] cos(θ)=cos Z S cos S+sin Z S sin S cos(A S -A)

[0017] Among them, I b is the direct solar radiation flux on the surface, τ b is the beam radiation transmittance, θ is the solar altitude angle, Z S is the solar zenith angle, A S is the solar azimuth, A is the slope direction of the ground, and S is the slope of the ground.

[0018] The present invention is further configured as follows: the calculation formula of the surface albedo in step S2 is:

[0019] α=0.356α1+0.130α3+0.373α4+0.085α5+0.072α7-0.0018

[0020] Among them, α is the surface albedo, α1 is the reflectivity of sensor 1 band, α3 is the reflectivity of sensor 3 band, α5 is the reflectivity of sensor 5 band, and α7 is the reflectivity of sensor 7 band.

[0021] The present invention is further configured as follows: the calculation formula of the solar radiation energy absorbed by the ground surface in step S3 is:

[0022] I a =I b *(1-α)*(1-ε)

[0023] Among them, I a is the solar radiation energy absorbed by the surface, and ε is the emissivity.

[0024] The present invention is further configured as follows: the calculation formula for the radiant heat information of the geological body in step S4 is:

[0025] I -S =LI a

[0026] Among them, I -S It is the radiation energy value of the geological body in the remote sensing image after removing the solar radiation, L is: the radiation value on the satellite, and the value after the remote sensing image thermal infrared band radiation calibration.

[0027] In summary, the present invention has the following beneficial effects:

[0028] 1. The energy obtained by the thermal infrared remote sensing image during the day is greatly affected by the solar radiation energy. The thermal infrared data of the earth's surface during the day is relatively large. By removing the solar radiation effect to observe the thermal radiation of the geological body, the energy radiated by the earth itself can be more accurately reflected, and the abnormal area can be found from it;

[0029] 2. The present invention obtains the heat radiation information of geological bodies by removing the solar radiation energy absorbed by the earth's surface with the relatively easy-to-obtain daytime thermal infrared data, and finds a method to use the daytime thermal infrared remote sensing data to reflect the energy value radiated outward by the earth itself, thereby avoiding the difficulty in obtaining thermal infrared remote sensing image data of the earth's surface at night and the reduction in data validity due to clouds. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a slope aspect map of the ground in the study area in the embodiment of the present invention;

[0031] Figure 2 is a slope map of the ground in the study area in the embodiment of the present invention;

[0032] Figure 3 is a surface temperature inversion map inverted based on the radiation transfer equation method in an embodiment of the present invention;

[0033] Figure 4 This is a thermal infrared remote sensing image after removing the solar radiation effect in the embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following is combined with Figure 1-4 The present invention is described in further detail.

[0035] Embodiment: A method for extracting radiation energy information of a geological body by removing the solar radiation effect comprises the following steps:

[0036] S1. Use the Landsat7 satellite ETM+ remote sensor to obtain the thermal infrared remote sensing image data of the earth's surface during the day. Calculate the vertical radiation flux density of the sun at the top of the atmosphere based on the thermal infrared remote sensing image data. The calculation formula for the vertical radiation flux density of the sun at the top of the atmosphere is:

[0037]

[0038] Where I0 is the vertical radiation flux density of the sun at the top of the atmosphere, S0 is the solar constant (1367W / m 2 ), DOY is the Galilean time of remote sensing image formation.

[0039] The direct radiation flux of the sun on the surface is calculated based on the vertical radiation flux density of the sun at the top of the atmosphere. The calculation formula for the direct radiation flux of the sun on the surface is:

[0040] I b =I0×τ b ×cos(θ)

[0041] cos(θ)=cos Z S cos S+sin Z S sin S cos(A S -A)

[0042] Among them, I b is the direct solar radiation flux on the surface, τ b is the beam radiation transmittance, θ is the solar altitude angle, Z S is the solar zenith angle, A S is the solar azimuth, A is the slope of the ground ( Figure 1 ), S is the slope of the ground ( Figure 2 ).

[0043] Z S =90°-θ

[0044] S2. Calculate the surface albedo. The surface albedo calculation formula is:

[0045] α=0.356α1+0.130α3+0.373α4+0.085α5+0.072α7-0.0018

[0046] Among them, α is the surface albedo, α1 is the ETM+1 band reflectivity, α3 is the ETM+3 band reflectivity, α5 is the ETM+5 band reflectivity, and α7 is the ETM+7 band reflectivity.

[0047] Surface albedo refers to the ratio of the surface's reflected flux of incident solar radiation to the incident solar radiation flux. It determines how much radiation energy is absorbed by the underlying surface and is therefore an important parameter in the study of surface energy balance.

[0048] S3. According to Kirchhoff's law, absorptivity = emissivity, that is, the greater the absorptivity of the ground object, the greater the emissivity; the solar radiation energy absorbed by the ground surface is calculated based on the ground surface albedo. The calculation formula for the solar radiation energy absorbed by the ground surface is:

[0049] I a =I b *(1-α)*(1-ε)

[0050] Among them, I a is the solar radiation energy absorbed by the surface, and ε is the emissivity.

[0051] The higher the emissivity, the longer the time required and the less heat received, so the absorbed heat is calculated by subtracting (1-ε).

[0052] The NDVI value calculation formula is:

[0053]

[0054] Among them, band4 is the remote sensing data of the 4th band of TM and ETM+ remote sensors carried by the US satellites Landsat 5 and Landsat 7 respectively, or it can be extended to the remote sensing data of the near-infrared band; band3 is the remote sensing data of the 3rd band of TM and ETM+ remote sensors carried by the US satellites Landsat 5 and Landsat 7 respectively, and it can also be extended to the remote sensing data of the red light band.

[0055] Vegetation coverage calculation: NDVI values ​​greater than 0.7 are assigned a value of 1, those less than 0.05 are assigned a value of 0, and those between 0.05 and 0.7 are assigned a value of ((b1-0.05) / (0.7-0.05)).

[0056] Emissivity calculation:

[0057] The emissivity of NDVI values ​​less than or equal to 0 is assigned to 0.995, and the emissivity of NDVI values ​​greater than 0 and less than 0.7 is assigned to (0.9589+0.086×b2-0.0671×b2 2 ), the emissivity greater than or equal to 0.7 is assigned as (0.9625+0.0614×b2-0.0461×b2 2 ), where b1 is NDVI and b2 is vegetation coverage.

[0058] S4. Remove the solar radiation energy absorbed by the surface from the thermal infrared remote sensing image data of the surface during the day, and calculate the radiation heat information of the geological body. The calculation formula of the radiation heat information of the geological body is:

[0059] I -S =LI a

[0060] Among them, I -S It is the radiation energy value of the geological body in the remote sensing image after removing the solar radiation, L is: the radiation value on the satellite, and the value after the remote sensing image thermal infrared band radiation calibration.

[0061] The thermal infrared remote sensing image after removing the solar radiation effect is shown in the figure below. Figure 4 As shown; Figure 4 The numerical unit is W / m 2 , is the radiation energy value, which reflects the energy radiated by the geological body after removing the solar radiation energy. By comparing and analyzing the extracted thermal radiation anomaly map after removing solar radiation with remote sensing maps, geological maps, and linear structural maps, it is found that its distribution has no obvious relationship with vegetation coverage, geological lithology, and structural information. To a certain extent, the interference of solar radiation, lithology, and vegetation coverage is eliminated, indicating that it reflects the energy radiated outward by the geological body and can reflect the deep heat situation.

[0062] In this embodiment, a thermal infrared temperature inversion control experiment based on the radiation transfer equation algorithm was conducted on the same data. The surface temperature inverted by the radiation transfer equation method is as follows: Figure 3 As shown in the figure, the overall temperature difference is small, and it is difficult to distinguish whether the high-value area is caused by geothermal resources or solar radiation. The temperature change of the surface is generally believed to be related to solar radiation and surface vegetation coverage. Compared with the thermal infrared remote sensing image after removing the solar radiation effect ( Figure 4 ) has obvious spatial distribution differences, which shows that the heat information after removing the solar radiation is not mainly caused by solar radiation and surface vegetation cover, but is the heat radiated outward by the earth itself.

[0063] Conclusion: Data at night is more difficult to obtain, and there are often clouds, so good data is even more difficult to obtain. This embodiment uses relatively easy-to-obtain daytime thermal infrared data to remove the solar radiation energy absorbed by the surface, thereby obtaining the radiation heat information of the geological body and finding a method to use daytime thermal infrared remote sensing data to reflect the energy value radiated outward by the earth itself; in general, the remote sensing image obtained by the geological body radiation value algorithm that removes the solar radiation effect can reflect the thermal information of the geological body, and has a very good reference value for finding hidden heat information.

[0064] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A method for extracting radiation energy information of a geological body by removing the solar radiation effect, characterized in that: The following steps are involved: S1. Use satellites to obtain thermal infrared remote sensing image data of the earth's surface during the day, calculate the vertical radiation flux density of the sun at the top of the atmosphere based on the thermal infrared remote sensing image data, and calculate the direct radiation flux of the sun on the surface based on the vertical radiation flux density of the sun at the top of the atmosphere; S2, calculate the surface albedo; S3, calculate the solar radiation energy absorbed by the surface according to the surface albedo; S4. Remove the solar radiation energy absorbed by the surface from the thermal infrared remote sensing image data of the surface during the day, and calculate the radiation heat information of the geological body.

2. The method for extracting radiation energy information of a geological body by removing solar radiation effect according to claim 1, characterized in that: The calculation formula of the vertical radiation flux density of the sun at the top of the atmosphere in step S1 is: Among them, I0 is the vertical radiation flux density of the sun at the top of the atmosphere, S0 is the solar constant, and DOY is the Galilean calendar time of remote sensing image formation. The calculation formula for the direct solar radiation flux on the earth's surface is: I b =I0×τ b ×cos(θ) cos(θ)=cosZ S cosS+sinZ S sinScos(A S -TO) Among them, I b is the direct solar radiation flux on the surface, τ b is the beam radiation transmittance, θ is the solar altitude angle, Z S is the solar zenith angle, A S is the solar azimuth, A is the slope direction of the ground, and S is the slope of the ground.

3. The method for extracting radiation energy information of a geological body by removing solar radiation effect according to claim 1, characterized in that: The calculation formula of the surface albedo in step S2 is: α＝0.356α1+0.130α3+0.373α4+0.085α5+0.072α7-0.0018 Among them, α is the surface albedo, α1 is the reflectivity of sensor 1 band, α3 is the reflectivity of sensor 3 band, α5 is the reflectivity of sensor 5 band, and α7 is the reflectivity of sensor 7 band.

4. The method for extracting geological body radiation energy information by removing solar radiation effect according to claim 1, characterized in that: The calculation formula of the solar radiation energy absorbed by the ground surface in step S3 is: I a =I b *(1-a)*(1-e) Among them, I a is the solar radiation energy absorbed by the surface, and ε is the emissivity.

5. The method for extracting geological body radiation energy information by removing solar radiation effect according to claim 1, characterized in that: The calculation formula of the radiant heat information of the geological body in step S4 is: I -S =L-I a Among them, I -S It is the radiation energy value of the geological body in the remote sensing image after removing the solar radiation, L is: the radiation value on the satellite, and the value after the remote sensing image thermal infrared band radiation calibration.

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