Litter coverage-considered forest hydrothermal transmission comprehensive model construction method and system

Abstract

The invention provides a method for constructing a forest hydrothermal transmission comprehensive model considering litter coverage. The method comprises the following steps: step 1, establishing an energy balance equation of a forest ecosystem considering litter coverage; step 2, respectively calculating net radiation flux, latent heat flux, sensible heat flux and soil heat flux of the forest ecosystem considering litter coverage; 3, coupling the energy balance equation with the hydrothermal transmission process equation based on latent heat flux, sensible heat flux, net radiation flux and soil heat flux of the forest ecosystem considering litter coverage, and establishing a forest ecosystem hydrothermal transmission comprehensive model considering litter coverage. And determining model parameters and solving the forest ecosystem hydrothermal transmission comprehensive model considering litter coverage. According to the method, accurate simulation of the annual hydrothermal transmission flux of the forest containing the litters can be realized only through driving of conventional weather and vegetation growth data, and the blank of forest hydrothermal transmission simulation research under the influence of litter coverage is filled.

Description

Technical Field

[0001] This invention belongs to the field of micrometeorology and plant physiology, specifically relating to a method and system for constructing a comprehensive forest water and heat transfer model that takes into account litter cover. Background Technology

[0002] Forest litter, as a crucial transitional zone at the vegetation-soil interface, significantly influences ecosystem hydrothermal transport processes through physical barriers, water retention regulation, and thermal resistance effects. Litter cover significantly impacts forest ecosystem hydrothermal transport by altering surface reflectivity and surface resistance. Existing research indicates that dynamic changes in litter cover have a significant impact on soil evaporation and surface energy distribution. However, most evapotranspiration models based on the Penman-Monteith equation do not adequately consider the regulatory mechanisms of the litter layer on evaporation, and traditional forest hydrothermal transport models often simplify the litter layer as a static medium of fixed thickness, neglecting its seasonal dynamic characteristics. Establishing a comprehensive model of forest ecosystem hydrothermal transport that accurately describes the dynamic characteristics of litter cover is of great significance for a deeper understanding of forest ecosystem hydrothermal cycles, optimizing forest resource management, and predicting the impacts of climate change on forest ecosystems. Summary of the Invention

[0003] In view of the shortcomings of the prior art described above, the purpose of this invention is to overcome the deficiencies of the prior art and to propose a method and system for constructing a comprehensive model of water and heat transfer in forest ecosystems that takes into account litter cover.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for constructing a comprehensive forest hydrothermal transport model that considers litter cover includes the following steps: Step 1. Establish the energy balance equation for a forest ecosystem that takes into account litter cover; Step 2. Calculate the net radiation flux, latent heat flux, sensible heat flux, and soil heat flux of the forest ecosystem considering litter cover; Step 3. Based on the latent heat flux, sensible heat flux, net radiation flux, and soil heat flux of the forest ecosystem considering litter cover, couple the energy balance equation with the water and heat transport process equation to establish a comprehensive water and heat transport model of the forest ecosystem considering litter cover, determine the model parameters, and solve the comprehensive water and heat transport model of the forest ecosystem considering litter cover.

[0005] Furthermore, the energy balance equation for the forest ecosystem considering litter cover is:

[0006] in, This represents the net radiation flux received by the forest ecosystem. ; For the latent heat flux of forest ecosystems, ; For the sensible heat flux of the forest ecosystem, ; For soil heat flux in forest ecosystems, .

[0007] Furthermore, the net radiation flux received by the forest ecosystem for:

[0008] in, For solar shortwave radiation, ; Albedo; It is the Stefan-Boltzmann constant; For air temperature, ; The surface emissivity of the sky; For surface temperature, .

[0009] Furthermore, the latent heat flux of the forest ecosystem for:

[0010] in, Let be the slope of the saturated water vapor pressure versus temperature curve. ; air density; The specific heat of dry air; For saturated water vapor pressure difference, ; For effective aerodynamic drag, ; For effective surface resistance, ; This is the hygrometer constant. .

[0011] Furthermore, effective aerodynamic drag Calculate using the following formula:

[0012] in, For canopy aerodynamic drag, ; For soil aerodynamic drag, , ; For the aerodynamic drag of the falling debris, , ; For atmospheric aerodynamic drag, , ; For average boundary layer resistance, ; The effective leaf area index, ; The height of the canopy at the site is in meters (m), obtained from actual measurements at the site. It is the eddy current diffusion attenuation coefficient; The turbulence attenuation coefficient is the height of the canopy. Let Roughness be the momentum roughness length, in meters. It is the zero-plane displacement height, in meters. It is the maximum aerodynamic drag of falling debris, obtained through calibration; For litter coverage; Effective surface resistance Calculate using the following formula:

[0013] in, For canopy surface resistance, ; For surface resistance, ; To minimize air resistance, This is obtained through rate determination; Represents photosynthetically active radiation The effect; The effect represents the pressure difference of saturated water vapor; Represents air temperature The effect; For soil surface resistance; For the surface resistance of fallen debris.

[0014] Furthermore, the sensible heat flux of the forest ecosystem for:

[0015] in, air density; The specific heat of dry air.

[0016] Furthermore, soil heat flux in forest ecosystems for:

[0017] in, This is the soil heat flux at a reference soil depth; It is the soil heat capacity. ; To calculate the time interval; The soil depth, in meters, is the soil heat flux to be calculated. For reference soil depth, in meters (m); For depth place, The surface temperature at any given moment; For depth place, The surface temperature at any given moment; This is the step size for calculating the required soil depth.

[0018] Furthermore, in step 6, the energy balance equation is combined with the water and heat transfer process equation to obtain the energy balance equation for a forest ecosystem that takes into account litter cover:

[0019] The above energy balance equation is about surface temperature. The equation is expressed in the following form: .

[0020] Furthermore, the energy balance equations are obtained by solving the nonlinear equation system using Newton's method. medium surface temperature Then, the net radiation flux, latent heat flux, sensible heat flux, and soil heat flux of the forest ecosystem, taking into account litter cover, can be calculated.

[0021] On the other hand, the present invention provides a system for constructing an integrated model of water and heat transport in a forest ecosystem that considers litter cover, comprising: Energy balance equation building module. It is used to build energy balance equations for forest ecosystems that take into account litter cover; The calculation module is used to calculate the net radiation flux, latent heat flux, sensible heat flux, and soil heat flux of a forest ecosystem that takes into account litter cover. The solution module is used to couple the energy balance equation with the water and heat transport process equation based on the latent heat flux, sensible heat flux, net radiation flux and soil heat flux of the forest ecosystem considering litter cover, to establish a comprehensive water and heat transport model of the forest ecosystem considering litter cover, determine the model parameters and solve the comprehensive water and heat transport model of the forest ecosystem considering litter cover.

[0022] Compared with the prior art, the present invention has the following beneficial effects: This invention, based on energy balance and turbulent transport theory, fully considers the hindering effect of forest litter cover on water and heat transport processes, and creatively proposes a comprehensive forest water and heat transport model that takes into account litter cover. The change in leaf area index reflects the litter cover status, and the comprehensive water and heat transport model considers the ability of litter to impede surface water and heat transport processes by influencing surface drag and aerodynamic drag. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is the overall flowchart of the present invention.

[0025] Figure 2 This is a comparison chart of simulated and measured values ​​of net radiation in a forest ecosystem, based on a comprehensive forest hydrothermal transport model that considers litter cover, according to an embodiment of the present invention.

[0026] Figure 3 This is a comparison chart of simulated and measured values ​​of latent heat flux in a forest ecosystem, based on a comprehensive forest hydrothermal transport model that considers litter cover, according to an embodiment of the present invention.

[0027] Figure 4 This is a comparison chart of simulated and measured values ​​of sensible heat flux in a forest ecosystem, based on a comprehensive forest hydrothermal transport model that considers litter cover, according to an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] Example 1 The invention will now be further described with reference to the accompanying drawings.

[0030] like Figure 1 As shown, this invention provides a method for constructing an integrated model of water and heat transport in a forest ecosystem that considers litter cover, comprising the following steps: Step 1. Establish the energy balance equation for a forest ecosystem that takes into account litter cover; Step 2. Calculate the net radiation flux, latent heat flux, sensible heat flux, and soil heat flux of the forest ecosystem considering litter cover; Step 3. Based on the latent heat flux, sensible heat flux, net radiation flux, and soil heat flux of the forest ecosystem considering litter cover, couple the energy balance equation with the water and heat transport process equation to establish a comprehensive water and heat transport model of the forest ecosystem considering litter cover, determine the model parameters, and solve the comprehensive water and heat transport model of the forest ecosystem considering litter cover.

[0031] Furthermore, the energy balance equation is:

[0032] in, Net radiation received by the forest ecosystem ( ), For forest ecosystem latent heat flux ( ), Sensible heat flux in forest ecosystems ( ), For forest ecosystem soil heat flux ( ).

[0033] Furthermore, the net radiation received by the forest ecosystem Calculate using the following formula:

[0034] in, For solar shortwave radiation ( (), obtained from observation data; Albedo, obtained from observational data; This is the Stefan-Boltzmann constant, with a value of [value missing]. ; air temperature ( (This is) obtained from observational data; The sky surface radiance coefficient is obtained from observational data; For surface temperature ( Net radiation The simulation results are as follows Figure 2 As shown.

[0035] Furthermore, the latent heat flux of forest ecosystems Calculate using the following formula:

[0036] in, The slope of the saturated water vapor pressure versus temperature curve ( ); The density is the air density, taken at room temperature. ; For the specific heat of dry air, take ; The saturated water vapor pressure difference ( (), obtained from observation data; For effective aerodynamic drag ( ); For effective surface resistance ( ); Hygrometer constant ( );

[0037] in, The atmospheric pressure (Pa) is obtained from observational data.

[0038] Effective aerodynamic drag is calculated using the following formula:

[0039]

[0040] in, For canopy aerodynamic drag ( ); Soil aerodynamic drag ( ); For the aerodynamic drag of falling debris ( ); Atmospheric aerodynamic drag ( ); For the average boundary layer drag, ; Effective leaf area index ( ); The height of the canopy at the site (m) is obtained from actual measurements at the site. It is the eddy current diffusion attenuation coefficient; The turbulence attenuation coefficient is the height of the canopy. The momentum roughness length (m); It is the zero-plane displacement height (m). The maximum aerodynamic drag of falling debris is 500. ; This represents litter cover. The above variables are calculated using the following formula and can be estimated using the following formula:

[0041] in, Ecosystem leaf area index ( (), obtained from on-site measured data or remote sensing products; Frictional wind speed ( (), obtained from observation data; is the von Karman constant, with a value of 0.41; For reference height ( ), obtained from actual site measurements; Maximum leaf area index ( ).

[0042] Effective surface resistance is calculated using the following formula:

[0043]

[0044] in, For canopy surface resistance ( ); For surface resistance ( ); Minimum air resistance ( For deciduous broad-leaved forests, take 100 ; Represents photosynthetically active radiation The effect; The effect represents the pressure difference of saturated water vapor; Represents air temperature The effect; For soil surface resistance; The surface resistance of the debris is given. The above variables are calculated using the following formula:

[0045] in, The maximum blade drag is set to 5000. ; Represents the net radiation received by the canopy ( ); The extinction coefficient is 0.7 for deciduous broad-leaved forest ecosystems. This is an empirical parameter, and its value is the reciprocal of the 99th quantile saturated water vapor pressure difference; To minimize soil surface resistance ( The calibration result was 60. ; The effect of soil water SWC; This is the field water holding capacity, obtained through actual measurement; The maximum surface resistance of the debris ( The calibration result is 500. Latent heat flux The simulation results are as follows Figure 3 As shown.

[0046] Furthermore, the sensible heat flux of forest ecosystems Calculate using the following formula:

[0047] Inductive heat flux The simulation results are as follows Figure 4 As shown.

[0048] Furthermore, soil heat flux in forest ecosystems Calculate using the following formula:

[0049] in, The soil heat flux at the reference soil depth is considered as 0. Soil heat capacity .

[0050] Furthermore, in step 6, the energy balance equation is combined with the water and heat transfer process equation to obtain the energy balance equation for a forest ecosystem that takes into account litter cover:

[0051] The above energy balance equation is for surface temperature The equation can be expressed in the following form:

[0052] The number of unknowns is equal to the number of equations, therefore it can be solved.

[0053] Furthermore, the energy balance equations are obtained by solving the nonlinear equation system using Newton's method. medium surface temperature Then, the components of net radiation, latent heat flux, sensible heat flux, and soil heat flux can be calculated.

[0054] Example 2 This embodiment provides a system for constructing a comprehensive model of water and heat transfer in a forest ecosystem that considers litter cover, including: Energy balance equation building module. It is used to build energy balance equations for forest ecosystems that take into account litter cover; The calculation module is used to calculate the net radiation flux, latent heat flux, sensible heat flux, and soil heat flux of a forest ecosystem that takes into account litter cover. The solution module is used to couple the energy balance equation with the water and heat transfer process equation based on the latent heat flux, sensible heat flux, net radiation flux and soil heat flux of the forest ecosystem considering litter cover, to establish a comprehensive water and heat transfer model of the forest ecosystem considering litter cover, determine the model parameters and solve the comprehensive water and heat transfer model of the forest ecosystem considering litter cover. It should be understood that any parts not described in detail in this specification belong to the prior art.

[0055] It should be understood that the above description of the preferred embodiments is quite detailed, but this should not be construed as limiting the scope of protection of this invention. It is neither necessary nor possible to exhaustively describe all possible implementations. Those skilled in the art, guided by this invention, can make substitutions or modifications without departing from the scope of the claims, all of which fall within the scope of protection of this invention. The scope of protection of this invention should be determined by the appended claims.

Claims

1. A method for constructing a comprehensive forest water and heat transfer model considering litter cover, characterized in that, Includes the following steps: Step 1. Establish the energy balance equation for a forest ecosystem that takes into account litter cover; Step 2. Calculate the net radiation flux, latent heat flux, sensible heat flux, and soil heat flux of the forest ecosystem considering litter cover; Step 3. Based on the latent heat flux, sensible heat flux, net radiation flux, and soil heat flux of the forest ecosystem considering litter cover, couple the energy balance equation with the water and heat transport process equation to establish a comprehensive water and heat transport model of the forest ecosystem considering litter cover, determine the model parameters, and solve the comprehensive water and heat transport model of the forest ecosystem considering litter cover.

2. The method for constructing a comprehensive forest hydrothermal transfer model considering litter cover according to claim 1, characterized in that, The energy balance equation for the forest ecosystem that takes into account litter cover is: in, This represents the net radiation flux received by the forest ecosystem. ; For the latent heat flux of forest ecosystems, ; For the sensible heat flux of the forest ecosystem, ; For soil heat flux in forest ecosystems, .

3. The method for constructing a comprehensive forest hydrothermal transfer model considering litter cover according to claim 2, characterized in that, The net radiation flux received by the forest ecosystem for: in, For solar shortwave radiation, ; Albedo; It is the Stefan-Boltzmann constant; For air temperature, ; The surface emissivity of the sky; For surface temperature, .

4. The method for constructing a comprehensive forest hydrothermal transfer model considering litter cover according to claim 3, characterized in that, The latent heat flux of the forest ecosystem for: in, Let be the slope of the saturated water vapor pressure versus temperature curve. ; air density; The specific heat of dry air; For saturated water vapor pressure difference, ; For effective aerodynamic drag, ; For effective surface resistance, ; This is the hygrometer constant. .

5. The method for constructing a comprehensive forest hydrothermal transfer model considering litter cover according to claim 4, characterized in that, Effective aerodynamic drag Calculate using the following formula: in, For canopy aerodynamic drag, ; For soil aerodynamic drag, , ; For the aerodynamic drag of the falling debris, , ; For atmospheric aerodynamic drag, , ; For average boundary layer resistance, ; The effective leaf area index, ; The height of the canopy at the site is in meters (m), obtained from actual measurements at the site. It is the eddy current diffusion attenuation coefficient; The turbulence attenuation coefficient is the height of the canopy. Let Roughness be the momentum roughness length, in meters. It is the zero-plane displacement height, in meters. It is the maximum aerodynamic drag of falling debris, obtained through calibration; For litter coverage; Effective surface resistance Calculate using the following formula: in, For canopy surface resistance, ; For surface resistance, ; To minimize air resistance, This is obtained through rate determination; Represents photosynthetically active radiation The effect; The effect represents the pressure difference of saturated water vapor; Represents air temperature The effect; For soil surface resistance; For the surface resistance of fallen debris.

6. The method for constructing a comprehensive forest hydrothermal transfer model considering litter cover according to claim 5, characterized in that: The heat flux of the forest ecosystem for: in, air density; The specific heat of dry air.

7. The method for constructing a comprehensive forest hydrothermal transfer model considering litter cover according to claim 6, characterized in that: Forest ecosystem soil heat flux for: in, This is the soil heat flux at a reference soil depth; It is the soil heat capacity. ; To calculate the time interval; The soil depth, in meters, is the soil heat flux to be calculated. For reference soil depth, in meters (m); For depth Place, The surface temperature at any given moment; For depth Place, The surface temperature at any given moment; This is the step size for calculating the required soil depth.

8. The method for constructing a comprehensive forest hydrothermal transfer model considering litter cover according to claim 1, characterized in that: In step 6, the energy balance equation is combined with the water and heat transport process equation to obtain the energy balance equation for a forest ecosystem that takes into account litter cover: The above energy balance equation is about surface temperature. The equation is expressed in the following form: .

9. A method for constructing a comprehensive forest hydrothermal transfer model considering litter cover as described in claim 8, characterized in that: The energy balance equations are obtained by solving the nonlinear equation system using Newton's method. medium surface temperature Then, the net radiation flux, latent heat flux, sensible heat flux, and soil heat flux of the forest ecosystem, taking into account litter cover, can be calculated.

10. A system for constructing a comprehensive forest hydrothermal transport model considering litter cover, characterized in that, include: Energy balance equation building module. It is used to build energy balance equations for forest ecosystems that take into account litter cover; The calculation module is used to calculate the net radiation flux, latent heat flux, sensible heat flux, and soil heat flux of a forest ecosystem that takes into account litter cover. The solution module is used to couple the energy balance equation with the water and heat transfer process equation based on the latent heat flux, sensible heat flux, net radiation flux and soil heat flux of the forest ecosystem considering litter cover, to establish a comprehensive water and heat transfer model of the forest ecosystem considering litter cover, determine the model parameters and solve the comprehensive water and heat transfer model of the forest ecosystem considering litter cover. The forest hydrothermal transport integrated model construction system that takes into account litter cover is used to perform the steps in the forest hydrothermal transport integrated model construction method that takes into account litter cover as described in any one of claims 1-9.

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