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

Abstract

The present invention discloses a tower base red light chlorophyll fluorescence inversion method, device, system, and storage medium, comprising: step S1, obtaining irradiance measured by a tower base sensor; step S2, using an improved 3FLD algorithm, correcting the tower base observed irradiance to the actual irradiance reaching the canopy top from different directions, and performing SIF inversion. The technical solution of the present invention can accurately obtain the actual incident radiation received by the top of the tower base vegetation observation canopy, while simultaneously improving the accuracy of tower base red light chlorophyll fluorescence inversion.

Description

Technical Field

[0001] The present 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 downward 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 the following problems exist:

[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 solutions:

[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 observation 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 method, 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, f 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.

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

[0018] The 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 observation 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 method, 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, f 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.

[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 the 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. 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 at 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any 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 the observed solar leaf LAI as a function of the observation zenith angle and the observation azimuth angle (relative to the solar azimuth angle); where the solar zenith angle is (A, D) 20°, (B, E) 48°, and (C, F) 60°, respectively. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall 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] Example 1:

[0039] like Figure 1 As shown, an embodiment of the present invention further 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 observation 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 the different ratios of direct light and scattered light when inverting RSIF. According to the standard 3FLD method, the irradiance is replaced by the actual irradiance reaching the top of the canopy at 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, f sun is the observed sun 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 observed sun leaf LAI for different SZA conditions and the observed sun leaf LAI ratio. 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 account for multiple scattering of radiation within the canopy, which is negligible in the red band.

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

[0053] Example 2:

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

[0055] The 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 observation 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 an 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, f 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.

[0064] Example 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 the tower base red light chlorophyll fluorescence inversion method when run by the processor.

[0066] Example 4:

[0067] An embodiment of the present invention provides a storage medium having a computer program stored thereon. When the computer program is run, the computer program executes a tower-based red light chlorophyll fluorescence inversion method.

[0068] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined 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 chlorophyll fluorescence extraction 3FLD algorithm, the tower base observed irradiance is corrected to the real irradiance reaching the top of the canopy in different directions to perform solar induced chlorophyll fluorescence (SIF) inversion; The irradiance measured by the tower base sensor includes: direct light and diffuse light; The calculation process of the improved chlorophyll fluorescence extraction 3FLD algorithm is as follows: E=f sun ×(E dir +E diff )+(1-f sun )×E diff f sun =L' sun_v / L v ×exp(-ξ / π) 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, f sun is the observed sun leaf L' sun_v As a percentage of the total observed LAIL v The product of the ratio and exp(-ξ / π), F(ξ) is the hotspot kernel function, ξ is the phase angle, and C controls the width of the hotspot.

2. A tower-based red light chlorophyll fluorescence inversion device, characterized in that: include: The acquisition module is used to obtain the irradiance measured by the tower base sensor; The inversion module is used to use the improved chlorophyll fluorescence extraction 3FLD algorithm to correct the tower base observation irradiance to the real irradiance reaching the top of the canopy in different directions for solar induced chlorophyll fluorescence SIF inversion; The irradiance measured by the tower base sensor includes: direct light and diffuse light; The calculation process of the improved chlorophyll fluorescence extraction 3FLD algorithm is as follows: E=f sun ×(E dir +E diff )+(1-f sun )×E diff f sun =L′ sun_v / L v ×exp(-ξ / π) 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, f sun is the observed sun leaf L' sun_v As a percentage of the total observed LAIL v The product of the ratio and exp(-ξ / π), F(ξ) is the hotspot kernel function, ξ is the phase angle, and C controls the width of the hotspot.

3. A tower-based 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 claimed in claim 1 is executed.

4. A storage medium, characterized in that The storage medium stores a computer program, which executes the tower base red light chlorophyll fluorescence inversion method according to claim 1 when running.

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