Tower footing red chlorophyll fluorescence inversion method, device and system and storage medium

Abstract

The invention discloses a tower footing red light chlorophyll fluorescence inversion method, device and system and a storage medium. The method comprises the following steps: S1, acquiring irradiance measured by a tower footing sensor; and S2, correcting the observation irradiance of the tower footing to real irradiance reaching the top of the canopy in different directions by using an improved 3FLD algorithm, and carrying out SIF inversion. By adopting the technical scheme of the invention, the incident radiation actually received by the top of the tower footing vegetation observation canopy can be accurately obtained, and meanwhile, the chlorophyll fluorescence inversion precision of the red light band of the tower footing is improved.

Description

Technical Field

[0001] The invention belongs to the field of SIF inversion, and in particular relates to a tower base red light chlorophyll fluorescence inversion method and device, system and storage medium. Background Art

[0002] When inverting SIF, the irradiance measured by the tower-based sensor should match the irradiance reaching the top of the canopy. The total downlink radiation observed by the sensor is the sum of direct light and diffuse light. However, the proportion of direct light or diffuse light reaching the top of the canopy depends on the observation direction. For example, the canopy in the direction of the hot spot receives direct light and diffuse light, but the canopy in the direction of the dark spot mainly receives diffuse light. Therefore, the irradiance observed by the sensor matches the irradiance in the direction of the hot spot, but does not match that in the direction of the dark spot. The different proportions of direct light and diffuse light will cause obvious directional errors in the inversion of SIF, especially in the red light band, and there are the following problems:

[0003] (1) It is impossible to accurately obtain the incident radiation actually received by the top of the vegetation observation canopy at the base of the tower;

[0004] (2) The accuracy of chlorophyll fluorescence inversion in the red light band of the tower base is low. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a tower base red light chlorophyll fluorescence inversion method and device, system and storage medium.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] A tower base red light chlorophyll fluorescence inversion method, comprising:

[0008] Step S1, obtaining the irradiance measured by the tower base sensor;

[0009] Step S2: Using the improved 3FLD algorithm, the tower base observed irradiance is corrected to the real irradiance reaching the top of the canopy in different directions for SIF inversion.

[0010] Preferably, the irradiance measured by the tower base sensor includes direct light and diffuse light.

[0011] As a preferred embodiment, the calculation process of the improved 3FLD algorithm is:

[0012] E=f sun ×(E dir +E diff )+(1-f sun )×E diff

[0013]

[0014] L′ sun_v =L sun_v +(L sun -L sun_v )×F(ξ)

[0015] F(ξ)=exp(-(ξ / π)×C)

[0016] Among them, E dir and E diff are direct light and diffuse light, respectively, sun is the observed positive leaf (L′ sun_v ) accounts for the total observed LAI (L v ), F(ξ) is the hotspot kernel function, ξ is the phase angle, and C controls the width of the hotspot.

[0017] The present invention also provides a tower base red light chlorophyll fluorescence inversion device, comprising:

[0018] An acquisition module is used to obtain the irradiance measured by the tower base sensor;

[0019] The inversion module is used to use the improved 3FLD algorithm to correct the tower base observed irradiance to the real irradiance reaching the top of the canopy in different directions for SIF inversion.

[0020] Preferably, the irradiance measured by the tower base sensor includes direct light and diffuse light.

[0021] As a preferred embodiment, the calculation process of the improved 3FLD algorithm is:

[0022] E=f sun ×(E dir +E diff )+(1-f sun )×E diff

[0023]

[0024] L′ sun_v =L sun_v +(L sun -L sun_v )×F(ξ)

[0025] F(ξ)=exp(-(ξ / π)×C)

[0026] Among them, E dir and E diff are direct light and diffuse light, respectively, sun is the observed positive leaf (L′ sun_v ) accounts for the total observed LAI (L v ), F(ξ) is the hotspot kernel function, ξ is the phase angle, and C controls the width of the hotspot.

[0027] The present invention also provides a tower base red light chlorophyll fluorescence inversion system, comprising: a memory and a processor, wherein the memory stores a computer program run by the processor, and the computer program executes a tower base red light chlorophyll fluorescence inversion method when run by the processor.

[0028] The present invention also provides a storage medium, on which a computer program is stored, and when the computer program is run, the tower base red light chlorophyll fluorescence inversion method is executed.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1. Accurately obtain the solar radiation actually received by the top of the vegetation canopy

[0031] 2. Achieve high-precision inversion of chlorophyll fluorescence in the red light band of the tower base

[0032] 3. Eliminate the influence of directional effect on radiation BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0034] Figure 1 This is a flow chart of a tower base red light chlorophyll fluorescence inversion method according to an embodiment of the present invention;

[0035] Figure 2 Hemispheric distribution of observed solar leaf LAI as a function of observation zenith angle and observation azimuth angle (relative to the solar azimuth angle); where the solar zenith angles are (A, D) 20°, (B, E) 48°, and (C, F) 60°, respectively. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Embodiment 1:

[0039] like Figure 1 As shown, the embodiment of the present invention also provides a tower base red light chlorophyll fluorescence inversion method, comprising:

[0040] Step S1, obtaining the irradiance measured by the tower base sensor;

[0041] Step S2: Using the improved 3FLD algorithm, the tower base observed irradiance is corrected to the real irradiance reaching the top of the canopy in different directions for SIF inversion.

[0042] As an implementation manner of the embodiment of the present invention, the irradiance measured by the tower base sensor includes: direct light and diffuse light.

[0043] As an implementation of an embodiment of the present invention, in step S2, an improved 3FLD algorithm is used to consider the changes in different proportions of direct light and scattered light when inverting RSIF. According to the standard 3FLD method, the irradiance is replaced by the real irradiance reaching the top of the canopy in different observation directions, as shown below:

[0044] E=f sun ×(E dir +E diff )+(1-f sun )×E diff (1)

[0045] f sun =L′ sun_v / L v (2)

[0046] L′ sun_v =L sun_v +(L sun -L sun_v )×F(ξ) (3)

[0047] F(ξ)=exp(-(ξ / π)×C) (4)

[0048] Among them, E dir and E diff are direct light and diffuse light, respectively, sun is the observed positive leaf (L′ sun_v ) accounts for the total observed LAI (L v ), F(ξ) is the hotspot kernel function used to resolve the correlation between the observation direction and the solar direction, ξ is the phase angle, and C controls the width of the hotspot.

[0049] f sun Based on formula (2), the observed solar leaf LAI ratio at high observation zenith angle is overestimated, such as Figure 2To solve this problem, the exponential function is introduced into equation (5) as follows:

[0050]

[0051] Figure 2 Figure 5 shows the hemispheric distribution of the observed sun leaf LAI for different SZA conditions and the proportion of the observed sun leaf LAI. In general, fsun is highest in the direction of the hotspot and decreases away from the hotspot. It should be noted that equation (5) does take into account multiple scattering of radiation within the canopy, which can be ignored in the red band.

[0052] The problem of red light SIF inversion that needs to be considered is that the incident radiation E measured by the sensor cannot represent the real E that actually reaches the canopy position. Therefore, the method of obtaining the real E by combining the four-scale model is as shown in formula (1). The calculated real E is substituted into the 3FLD algorithm to invert the red light SIF. In the red light band (ignoring the multiple scattering effect), for the sun leaves, direct radiation and diffuse radiation are received, and the incident radiation E measured by the sensor is approximately the same as the real E that actually reaches the canopy position. However, for the shade leaves, they only receive diffuse radiation, and the incident radiation E (direct + diffuse) measured by the sensor is different from the real E (diffuse) that actually reaches the canopy position. Therefore, formula 1 expresses: the real incident radiation E received by the canopy is the sum of the radiation received by the shade leaves and the sun leaves respectively. For the sun leaves, the real radiation received is the observed sun leaf ratio multiplied by the sum of the direct radiation and diffuse radiation received by the sun leaves, while for the shade leaves, they only receive diffuse radiation, so it is expressed as the observed shade leaf ratio multiplied by the received diffuse radiation.

[0053] Embodiment 2:

[0054] The embodiment of the present invention further provides a tower base red light chlorophyll fluorescence inversion device, comprising:

[0055] An acquisition module is used to obtain the irradiance measured by the tower base sensor;

[0056] The inversion module is used to use the improved 3FLD algorithm to correct the tower base observed irradiance to the real irradiance reaching the top of the canopy in different directions for SIF inversion.

[0057] As an implementation manner of the embodiment of the present invention, the irradiance measured by the tower base sensor includes: direct light and diffuse light.

[0058] As an implementation method of the embodiment of the present invention, the calculation process of the improved 3FLD algorithm is:

[0059] E=f sun ×(E dir +E diff )+(1-f sum )×Ediff

[0060]

[0061] L′ sun_v =L sun_v +(L sun -L sum_v )×F(ξ)

[0062] F(ξ)=exp(-(ξ / π)×C)

[0063] Among them, E dir and E diff are direct light and diffuse light, respectively, sun is the observed positive leaf (L′ sun_v ) accounts for the total observed LAI (L v ), F(ξ) is the hotspot kernel function, ξ is the phase angle, and C controls the width of the hotspot.

[0064] Embodiment 3:

[0065] An embodiment of the present invention also provides a tower base red light chlorophyll fluorescence inversion system, comprising: a memory and a processor, wherein the memory stores a computer program run by the processor, and the computer program executes a tower base red light chlorophyll fluorescence inversion method when run by the processor.

[0066] Embodiment 4:

[0067] An embodiment of the present invention provides a storage medium, on which a computer program is stored. When the computer program is run, a tower base red light chlorophyll fluorescence inversion method is executed.

[0068] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A tower base red light chlorophyll fluorescence inversion method, characterized in that: include: Step S1, obtaining the irradiance measured by the tower base sensor; Step S2: Using the improved 3FLD algorithm, the tower base observed irradiance is corrected to the real irradiance reaching the top of the canopy in different directions for SIF inversion.

2. The tower base red light chlorophyll fluorescence inversion method as claimed in claim 1, characterized in that: The irradiance measured by the tower base sensor includes: direct light and diffuse light.

3. The tower base red light chlorophyll fluorescence inversion method as claimed in claim 2, characterized in that: The calculation process of the improved 3FLD algorithm is: E=f sun ×(E dir +E diff )+(1-f sun )×E diff L' sun_v l sun_v +(L sun -L sun_v )×F(ξ) F(ξ)=exp(-(ξ / π)×C) Among them, E dir and E diff are direct light and diffuse light, respectively, sun is the observed sun leaf (L' sum_v ) accounts for the total observed LAI (L v ), F(ξ) is the hotspot kernel function, ξ is the phase angle, and C controls the width of the hotspot.

4. A tower-based red light chlorophyll fluorescence inversion device, characterized in that: include: An acquisition module is used to obtain the irradiance measured by the tower base sensor; The inversion module is used to use the improved 3FLD algorithm to correct the tower base observed irradiance to the real irradiance reaching the top of the canopy in different directions for SIF inversion.

5. The tower base red light chlorophyll fluorescence inversion device as claimed in claim 4, characterized in that: The irradiance measured by the tower base sensor includes: direct light and diffuse light.

6. The tower base red light chlorophyll fluorescence inversion device as claimed in claim 5, characterized in that: The calculation process of the improved 3FLD algorithm is: E=f sun ×(E dir +E diff )+(1-f sum )×E diff L' sun_v =L sun_v +(L sun -L sum_v )×F(ξ) F(ξ)=exp(-(ξ / π)×C) Among them, E dir and E diff are direct light and diffuse light, respectively, sun is the observed sun leaf (L' sun_v ) accounts for the total observed LAI (L v ), F(ξ) is the hotspot kernel function, ξ is the phase angle, and C controls the width of the hotspot.

7. A tower base red light chlorophyll fluorescence inversion system, characterized in that: include: A memory and a processor, wherein the memory stores a computer program executed by the processor, and when the computer program is executed by the processor, the tower base red light chlorophyll fluorescence inversion method as described in any one of claims 1 to 3 is executed.

8. A storage medium, characterized in that: The storage medium stores a computer program, which, when running, executes the tower base red light chlorophyll fluorescence inversion method as described in any one of claims 1 to 3.

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