Surface evapotranspiration estimation method

Abstract

A surface evapotranspiration estimation method, comprising: constructing a time continuity equation for the temperature and the specific humidity in a boundary layer of a land-atmosphere coupling system (S1); in combination with the relationships between a saturated water vapor deficit and the temperature and the specific humidity, determining a time continuity equation for the saturated water vapor deficit in the boundary layer (S2); constructing a first-order non-homogeneous ordinary differential equation for the saturated water vapor deficit in the boundary layer, so as to calculate the relationships between the saturated water vapor deficit in the boundary layer and a saturated water vapor deficit in an entrainment layer, a saturated water vapor deficit on the surface and a land-atmosphere coupling factor, respectively (S3); in combination with a surface energy balance equation and a water vapor transmission equation, obtaining a surface evapotranspiration representation equation under a land-atmosphere coupling effect (S4); and deriving equations representing the contributions of a radiation term, a surface term, an atmospheric term, and a land-atmosphere coupling term to the surface evapotranspiration, thereby quantifying the magnitude of the influence of land-atmosphere coupling on the surface evapotranspiration (S5).

Description

Methods for estimating surface evapotranspiration

[0001] This application claims priority to Chinese Patent Application No. 202411469942.4, filed with the Chinese Patent Office on October 21, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of surface evapotranspiration estimation, and for example relates to a method for estimating surface evapotranspiration. Background Technology

[0003] Evapotranspiration is a crucial process in the water and energy cycle of the land-atmosphere system, and a key indicator for meteorological and hydrological simulation and crop water requirement forecasting. Exploring the mechanisms of surface evapotranspiration changes under land-atmosphere interactions is of great significance for improving the accuracy of surface evapotranspiration estimation, rationally optimizing crop irrigation regimes, and accurately guiding agricultural water demand management.

[0004] Surface evapotranspiration refers to the process by which water vapor from the soil / vegetation surface and free water surface escapes into the free atmosphere within the land-near-surface atmosphere, driven by solar radiation. It includes water (land) surface evaporation, vegetation transpiration, and canopy interception. Currently, the most widely used evapotranspiration estimation models are primarily based on Penman's theory. This theory assumes a constant water vapor content within the atmospheric boundary layer and focuses on describing the response of surface moisture supply and near-surface atmospheric conditions to the evapotranspiration process. By considering different aspects of the heterogeneity of underlying surface moisture-energy-vegetation characteristics, single-source, dual-source, multi-source, and sparse vegetation evapotranspiration models have been successively developed. However, evapotranspiration models based on a land surface perspective do not adequately consider the impact of atmospheric state changes on the evapotranspiration process. Summary of the Invention

[0005] This application provides a method for estimating surface evapotranspiration, which solves the problem that methods in related technologies cannot characterize the land-atmosphere coupling effect, such as the influence of the atmospheric boundary layer top entrainment effect on the surface evapotranspiration process. At the same time, it proposes a contribution rate expression to quantify the contributions of radiation, land surface, atmosphere and land-atmosphere coupling terms to the evapotranspiration process.

[0006] The technical solution adopted in this application is:

[0007] A method for estimating surface evapotranspiration includes:

[0008] Based on the boundary layer water and heat transfer theory, the functional relationship between temperature and specific humidity and water and heat fluxes at the top of the surface and atmospheric boundary layer in the land-atmosphere coupled system is derived, and the time continuity equations for temperature and specific humidity are constructed.

[0009] Based on the time continuity equations for temperature and specific humidity, and combined with the relationship between the saturated water vapor deficit D and temperature and specific humidity, the saturated water vapor deficit within the boundary layer is derived. The time continuity equation;

[0010] Constructing the saturated water vapor deficit within the boundary layer The first-order nonhomogeneous ordinary differential equation was solved, and the saturated water vapor deficit in the boundary layer was obtained. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit And the relationship between land-atmosphere coupling factors;

[0011] Based on the saturated water vapor deficit in the boundary layer The time continuity equation is used to derive the relationship between surface evapotranspiration and the saturated water vapor deficit in the boundary layer. The functional relationship, combined with the surface energy balance equation and water vapor transport equation, as well as the saturated water vapor deficit within the boundary layer. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit Based on the relationship between the land-atmosphere coupling factor and the land-atmosphere coupling factor, the surface evapotranspiration characterization equation under the land-atmosphere coupling effect is obtained;

[0012] Based on the surface evapotranspiration characterization equation under land-atmosphere coupling, equations for the contributions of radiation, surface, atmospheric, and land-atmosphere coupling terms to surface evapotranspiration are derived to quantify the magnitude of the impact of land-atmosphere coupling on surface evapotranspiration.

[0013] In one embodiment, the time continuity equations for temperature and specific humidity are as follows:

[0014] ;

[0015] ;

[0016] in, and These represent the potential temperature and specific humidity inside the boundary layer, respectively. and They represent sensible heat flux and latent heat energy at the Earth's surface, respectively. This represents the air density inside the boundary layer. Indicates specific heat at constant pressure. Indicates the height of the atmospheric boundary layer. This represents the average flow velocity at the top of the boundary layer. and These represent the temperature and specific humidity of the roll layer, respectively. Indicates a time period. It represents the latent heat of vaporization.

[0017] In one embodiment, the saturated water vapor deficit within the boundary layer The time continuity equation is as follows:

[0018] ;

[0019] in, Indicates time, This represents the slope of the saturated specific humidity-potential temperature curve. and They represent sensible heat flux and latent heat energy at the Earth's surface, respectively. This represents the air density inside the boundary layer. Indicates the height of the atmospheric boundary layer. Indicates the latent heat of vaporization. This represents the average flow velocity at the top of the boundary layer. Indicates specific heat at constant pressure. Indicates the temperature of the sandwich layer. This represents the potential temperature inside the boundary layer. Indicates the specific humidity of the sandwich layer. This indicates the specific humidity within the boundary layer.

[0020] In one embodiment, the saturated water vapor deficit within the boundary layer With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit The expression for the relationship between the land-atmosphere coupling factor is as follows:

[0021] ;

[0022] ;

[0023] ;

[0024] in, This indicates the relative transport rate of land-atmosphere coupling. Indicates the land-atmosphere coupling time ratio. Indicates the initial saturation water vapor deficit within the atmospheric boundary layer. Indicates the winding rate, Indicates the surface transmission rate. Indicates the duration of land-atmosphere coupling. Indicates a time period.

[0025] In one embodiment, the surface evapotranspiration characterization equation is as follows:

[0026] ;

[0027] in, This represents the latent heat flux at the Earth's surface. and These represent net surface radiation and soil heat flux, respectively. This represents the air density inside the boundary layer. Indicates the latent heat of vaporization. This represents the hygrometer constant within the boundary layer. Indicates the surface transmission rate. Indicates the land-atmosphere coupling time ratio. This indicates the relative transport rate of land-atmosphere coupling. and These represent the sensible heat flux and the latent heat energy at the Earth's surface, respectively.

[0028] In one embodiment, the equation for the contribution of the radiation term to surface evapotranspiration is as follows:

[0029]

[0030] ;

[0031] in, This represents the contribution rate of the radiation term to surface evapotranspiration. Indicates the latent heat of vaporization. This represents the radiation term that affects evapotranspiration. Indicates surface evaporation. Indicates net radiation at the Earth's surface. Indicates soil heat flux. This represents the hygrometer constant within the boundary layer. This indicates the air density within the boundary layer. Indicates the latent heat of vaporization. Indicates the surface transmission rate. Indicates the land-atmosphere coupling time ratio. This indicates the relative transport rate of land-air coupling.

[0032] In one embodiment, the equation for the contribution of the surface term to surface evapotranspiration is as follows:

[0033]

[0034] ;

[0035] in, This represents the contribution rate of surface terms to surface evapotranspiration. This refers to surface parameters that affect evapotranspiration.

[0036] In one embodiment, the equation for the contribution of the atmospheric term to surface evapotranspiration is as follows:

[0037]

[0038] ;

[0039] in, This represents the contribution rate of atmospheric terms to surface evapotranspiration. This indicates atmospheric terms that affect evaporation.

[0040] In one embodiment, the equation for the contribution of the land-atmosphere coupling term to surface evapotranspiration is as follows:

[0041]

[0042] ;

[0043] in, This represents the contribution rate of the land-atmosphere coupling term to surface evapotranspiration. This indicates the land-atmosphere coupling term.

[0044] This application also provides a surface evapotranspiration estimation device, comprising:

[0045] The first equation construction module is set to derive the functional relationship between temperature and specific humidity and surface and atmospheric boundary layer top water and heat fluxes based on the boundary layer water and heat transfer theory, and construct the time continuity equation of temperature and specific humidity.

[0046] The second equation construction module is set up to be based on the time continuity equation of temperature and specific humidity. Combining the relationship between saturated water vapor deficit D and temperature and specific humidity, the saturated water vapor deficit in the boundary layer is derived. The time continuity equation;

[0047] The third equation construction module is set up to construct the saturated water vapor deficit within the boundary layer. The first-order nonhomogeneous ordinary differential equation was solved, and the saturated water vapor deficit in the boundary layer was obtained. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit And the relationship between land-atmosphere coupling factors;

[0048] The fourth equation construction module is set to be based on the saturated water vapor deficit within the boundary layer. The time continuity equation is used to derive the relationship between surface evapotranspiration and the saturated water vapor deficit in the boundary layer. The functional relationship, combined with the surface energy balance equation and water vapor transport equation, as well as the saturated water vapor deficit within the boundary layer. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit Based on the relationship between the land-atmosphere coupling factor and the land-atmosphere coupling factor, the surface evapotranspiration characterization equation under the land-atmosphere coupling effect is obtained;

[0049] The fifth equation construction module is set up as a characterization equation for surface evapotranspiration based on land-atmosphere coupling. It derives equations for the contributions of radiation, surface, atmospheric, and land-atmosphere coupling terms to surface evapotranspiration, and quantifies the magnitude of the influence of land-atmosphere coupling on evapotranspiration.

[0050] This application also provides an electronic device, including:

[0051] At least one processor; and

[0052] A memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform any of the surface evapotranspiration estimation methods described above. Attached Figure Description

[0053] Figure 1 is a flowchart of a surface evapotranspiration estimation method that considers land-atmosphere coupling in this embodiment.

[0054] Figure 2 is a schematic diagram of water and heat transfer in the boundary layer of the land-atmosphere coupling system in this embodiment.

[0055] Figure 3 is a schematic diagram of the method for estimating surface evapotranspiration under the interaction of land and air in this embodiment.

[0056] Figure 4 is a schematic diagram of the surface evapotranspiration estimation device considering the land-atmosphere coupling effect in this embodiment.

[0057] Figure 5 is a schematic diagram of an electronic device in this embodiment. Detailed Implementation

[0058] Example

[0059] As shown in Figure 1, this application provides a method for estimating surface evapotranspiration that considers land-atmosphere coupling, and its implementation method is as follows:

[0060] S1. Based on the boundary layer water and heat transfer theory, the functional relationship between temperature and specific humidity and water and heat flux at the top of the surface and atmospheric boundary layer in the land-atmosphere coupled system is derived, and the time continuity equation of temperature and specific humidity is constructed.

[0061] As shown in Figures 2 and 3, in this embodiment, the hydrothermal factors of the surface layer, the atmospheric boundary layer, and the atmospheric entrainment layer interact and constrain each other under the land-atmosphere coupling effect. It is assumed that the atmospheric elements (potential temperature and specific humidity) within the boundary layer are approximately in a steady state over a time period (dt), while the changes in the state of these atmospheric elements are influenced by both land surface processes (surface layer) and atmospheric processes (entrainment layer). The research object is generalized as a volume R with a boundary surface of... A well-mixed column of air. To determine the mass of air entering R, assume that the boundary layer top (above R) passes through... The average flow velocity is The mass flow of air into R is ,in, Let represent the air density. For a fully mixed R, the equations for the conservation of internal potential temperature and specific humidity are as follows:

[0062] (1)

[0063] (2)

[0064] Where R represents the volume of the air column ( ), ρ represents the air density inside the boundary layer ( ), Indicates specific heat at constant pressure ( )), and These represent the rates of change of potential temperature within the boundary layer ( ) and specific humidity change rate (g / kg / s). and These represent the areas of the water-heat exchange interfaces between the Earth's surface and the top of the atmosphere and the interior of the boundary layer, respectively. ), and They represent the sensible heat flux and the latent heat flux at the surface, respectively. , It represents the latent heat of vaporization (kJ / kg). and These represent the potential temperatures inside the boundary layer ( ) and specific humidity (g / kg), and These represent the potential temperatures of the roll layers ( ) and specific humidity (g / kg); This represents the average flow velocity at the top of the boundary layer, or the entrainment rate (m / s).

[0065] Assuming the three-dimensional air column R is regular, then approximately: ,in, The height of the atmospheric boundary layer is represented by . Substituting equations (1) and (2), the conservation equations for potential temperature and specific humidity within the system can be written as:

[0066] (3)

[0067] (4)

[0068] in, and These represent the potential temperature and specific humidity inside the boundary layer, respectively. and They represent sensible heat flux and latent heat energy at the Earth's surface, respectively. This represents the air density inside the boundary layer. Indicates specific heat at constant pressure. Indicates the height of the atmospheric boundary layer. This represents the average flow velocity at the top of the boundary layer. and These represent the temperature and specific humidity of the roll layer, respectively. Indicates a time period. It represents the latent heat of vaporization.

[0069] S2. Based on the time continuity equations for temperature and specific humidity, and combining the relationship between the saturated water vapor deficit D and temperature and specific humidity, the saturated water vapor deficit within the boundary layer is derived. The time continuity equation.

[0070] In this embodiment, the surface energy flux of the land-atmosphere coupling system and By potential temperature and wet Effect on saturated water vapor deficit , The relationship between potential temperature and specific humidity is as follows:

[0071] (5)

[0072] in, Indicates saturated specific humidity. This represents the potential temperature inside the boundary layer. This indicates the actual specific humidity inside the boundary layer. This indicates the corresponding functional relationship.

[0073] Taking the partial derivatives with respect to position temperature and specific humidity respectively, we have:

[0074] (6)

[0075] (7)

[0076] in, Indicates the saturated specific humidity within the boundary layer. Indicates specific heat at constant pressure. This represents the slope of the saturated specific humidity-potential temperature curve. It represents the latent heat of vaporization.

[0077] Then we can obtain the continuity equation for the saturated water vapor deficit time:

[0078] (8)

[0079] in, Indicates a time period.

[0080] Substituting equations (6) and (7) into equation (8), we get:

[0081] (9)

[0082] S3. Construct the saturated water vapor deficit within the boundary layer. The first-order nonhomogeneous ordinary differential equation was solved, and the saturated water vapor deficit in the boundary layer was obtained. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit And the relationship between land-atmosphere coupling factors;

[0083] In this embodiment, the first term on the right side of equation (9) represents the effect of changes in surface sensible heat flux and latent heat flux on the change in water vapor deficit within the boundary layer. The second term on the right side of the equation is transformed as follows:

[0084] (10)

[0085] in, This represents an approximate value of the slope of the saturated specific humidity-potential temperature curve. Indicates the saturated specific humidity of the sandwich layer. This indicates the saturated specific humidity within the boundary layer.

[0086] definition:

[0087] (11)

[0088] (12)

[0089] (13)

[0090] in, This represents the change in saturated water vapor deficit R caused by the entry of water vapor into the boundary layer through the Earth's surface. This represents the change in saturated water vapor deficit caused by the exchange with R through the entrainment process. This represents the error arising from the linear assumption made regarding the slope of the saturated water vapor deficit-temperature equation (using a tangent instead of a secant for the slope value), a crucial assumption used in the derivation of the Penman-Monteith equation. The calculation formula is as follows:

[0091] (14)

[0092] in, Indicates the temperature. Indicates the saturated specific humidity of the sandwich layer. This indicates the saturated specific humidity within the boundary layer.

[0093] because Very close to 0, therefore It is a negligible nonlinear value, that is Approximately:

[0094] (15)

[0095] definition:

[0096] (16)

[0097] (17)

[0098] (18)

[0099] Equation (15) above can be regarded as about The first-order nonhomogeneous ordinary differential equation can be obtained by solving the equation:

[0100] (19)

[0101] in, This indicates the relative transport rate of land-atmosphere coupling. Indicates the land-atmosphere coupling time ratio. Indicates the initial saturation water vapor deficit within the atmospheric boundary layer. Indicates the winding rate, Indicates the surface transmission rate. Indicates the duration of land-atmosphere coupling. The time period represents the time (s) required for the boundary layer to reach a steady state under the interaction of land and air.

[0102] Equation (19) above represents the saturated water vapor deficit in the boundary layer. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit And the general relationship between land-atmosphere coupling factors.

[0103] S4, Based on the saturated water vapor deficit within the boundary layer The time continuity equation is used to derive the relationship between surface evapotranspiration and the saturated water vapor deficit in the boundary layer. By combining the functional relationship of the land surface energy balance equation, the water vapor transport equation, and the relationship obtained in step S3, the surface evapotranspiration characterization equation under the land-atmosphere coupling effect is obtained.

[0104] In this embodiment, the surface energy balance equation is:

[0105] (20)

[0106] in, and They represent sensible heat flux and latent heat energy at the Earth's surface, respectively. and These represent net surface radiation and soil heat flux, respectively, in units of ( ). ).

[0107] Combining (20) and (19), and substituting them into (11), we get:

[0108] ;(twenty one)

[0109] in, This represents the latent heat flux at the Earth's surface. and These represent net surface radiation and soil heat flux, respectively. This represents the air density inside the boundary layer. Indicates the latent heat of vaporization. This represents the hygrometer constant within the boundary layer. Indicates the surface transmission rate. Indicates the land-atmosphere coupling time ratio. This indicates the relative transport rate of land-air coupling.

[0110] Equation (21) above is the surface evapotranspiration characterization equation under the interaction of land and air.

[0111] S5. Based on the surface evapotranspiration characterization equation under land-atmosphere coupling, derive the equations for the contributions of radiation, surface, atmospheric, and land-atmosphere coupling terms to surface evapotranspiration, quantify the magnitude of the influence of land-atmosphere coupling on evapotranspiration, and complete the estimation of surface evapotranspiration.

[0112] In this embodiment, to clarify the influence of different components on the evaporation process, this application proposes contribution rate expressions for four components:

[0113] The equation for the contribution of radiation to surface evapotranspiration is as follows:

[0114] ;

[0115] in, This represents the contribution rate of the radiation term to surface evapotranspiration. Indicates the latent heat of vaporization. This represents the radiation term that affects evapotranspiration. Indicates surface evaporation. Indicates net radiation at the Earth's surface. Indicates soil heat flux. This represents the hygrometer constant within the boundary layer. This indicates the air density within the boundary layer. Indicates the latent heat of vaporization. Indicates the surface transmission rate. Indicates the land-atmosphere coupling time ratio. This indicates the relative transport rate of land-air coupling.

[0116] The equation for the contribution of the surface term to surface evapotranspiration is as follows:

[0117]

[0118] ;

[0119] in, This represents the contribution rate of surface terms to surface evapotranspiration. This refers to surface parameters that affect evapotranspiration.

[0120] The equation for the atmospheric contribution to surface evapotranspiration is as follows:

[0121]

[0122] ;

[0123] in, This represents the contribution rate of atmospheric terms to surface evapotranspiration. This indicates atmospheric terms that affect evaporation.

[0124] The equation for the contribution of the land-atmosphere coupling term to surface evapotranspiration is as follows:

[0125]

[0126] ;

[0127] in, This represents the contribution rate of the land-atmosphere coupling term to surface evapotranspiration. This indicates the land-atmosphere coupling term.

[0128] As shown in Figure 4, this application also provides a surface evapotranspiration estimation device that considers land-atmosphere coupling. This device can be configured in an electronic device and includes:

[0129] The first equation construction module 10 is set to derive the functional relationship between temperature and specific humidity and surface and atmospheric boundary layer top water and heat flux based on the boundary layer water and heat transfer theory, and construct the time continuity equation of temperature and specific humidity.

[0130] The second equation construction module 20 is set up as a time continuity equation based on temperature and specific humidity. Combining the relationship between saturated water vapor deficit D and temperature and specific humidity, it derives the saturated water vapor deficit within the boundary layer. The time continuity equation;

[0131] The third equation construction module 30 is configured to construct the saturated water vapor deficit within the boundary layer. The first-order nonhomogeneous ordinary differential equation was solved, and the saturated water vapor deficit in the boundary layer was obtained. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit And the relationship between land-atmosphere coupling factors;

[0132] The fourth equation construction module 40 is configured to be based on the saturated water vapor deficit within the boundary layer. The time continuity equation is used to derive the relationship between surface evapotranspiration and the saturated water vapor deficit in the boundary layer. The functional relationship, combined with the surface energy balance equation and water vapor transport equation, as well as the saturated water vapor deficit within the boundary layer. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit Based on the relationship between the land-atmosphere coupling factor and the land-atmosphere coupling factor, the surface evapotranspiration characterization equation under the land-atmosphere coupling effect is obtained;

[0133] The fifth equation construction module 50 is set as a surface evapotranspiration characterization equation based on land-atmosphere coupling. It derives the equations for the contributions of radiation, surface, atmospheric and land-atmosphere coupling terms to surface evapotranspiration, and quantifies the magnitude of the influence of land-atmosphere coupling on evapotranspiration.

[0134] As shown in Figure 5, this application also provides an electronic device, including:

[0135] At least one processor 100; and

[0136] A memory 200 communicatively connected to the at least one processor 100; wherein the memory 200 stores a computer program executable by the at least one processor 100, the computer program being executed by the at least one processor 100 to enable the at least one processor 100 to perform any of the methods for estimating surface evapotranspiration considering land-atmosphere coupling.

[0137] This application proposes a new method for estimating evapotranspiration while considering the impact of land-atmosphere coupling on the evapotranspiration process, such as the influence of the entrainment process at the top of the atmospheric boundary layer on the evapotranspiration process. This helps to deepen the understanding of the surface evapotranspiration response mechanism under the background of climate change and improve the scientificity and accuracy of evapotranspiration estimation.

[0138] Based on the boundary layer water and heat transport theory and combined with the surface energy balance equation, a surface evapotranspiration estimation equation under land-atmosphere coupling was constructed. The influence of radiation, land surface, atmospheric, and land-atmosphere coupling terms on the evapotranspiration process was analyzed, and a contribution rate expression was proposed to quantitatively characterize the land-atmosphere coupling effect, thereby improving the comprehensiveness of the attribution analysis of evapotranspiration changes. Quantitative analysis of the attribution of evapotranspiration changes helps to accurately identify its main controlling factors, which is of great theoretical significance for scientifically understanding the mechanism of surface evapotranspiration processes under the background of intensified climate change. It also provides theoretical support for precise crop water management and fine simulation of the hydrological cycle.

[0139] Starting from the boundary layer water and heat transport continuity equation, this application fully considers the influence of land surface processes and free atmospheric processes on the water and heat inside the boundary layer. Through mathematical derivation, a full-process characterization model of evapotranspiration under land-atmosphere coupling is constructed, which can reveal the response mechanism of the entire surface evapotranspiration process, in order to improve the understanding of the mechanism of surface evapotranspiration.

Claims

1. A method for estimating surface evapotranspiration, comprising: Based on the boundary layer water and heat transfer theory, the functional relationship between temperature and specific humidity and water and heat fluxes at the top of the surface and atmospheric boundary layer in the land-atmosphere coupled system is derived, and the time continuity equations for temperature and specific humidity are constructed. Based on the time continuity equations for temperature and specific humidity, and combined with the relationship between the saturated water vapor deficit D and temperature and specific humidity, the saturated water vapor deficit within the boundary layer is derived. The time continuity equation; Constructing the saturated water vapor deficit within the boundary layer The first-order nonhomogeneous ordinary differential equation was solved, and the saturated water vapor deficit in the boundary layer was obtained. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit And the relationship between land-atmosphere coupling factors; Based on the saturated water vapor deficit in the boundary layer The time continuity equation is used to derive the relationship between surface evapotranspiration and the saturated water vapor deficit in the boundary layer. The functional relationship, combined with the surface energy balance equation and water vapor transport equation, as well as the saturated water vapor deficit within the boundary layer. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit Based on the relationship between the land-atmosphere coupling factor and the land-atmosphere coupling factor, the surface evapotranspiration characterization equation under the land-atmosphere coupling effect is obtained; Based on the surface evapotranspiration characterization equation under land-atmosphere coupling, equations for the contributions of radiation, surface, atmospheric, and land-atmosphere coupling terms to surface evapotranspiration are derived to quantify the magnitude of the impact of land-atmosphere coupling on surface evapotranspiration.

2. The method for estimating surface evapotranspiration according to claim 1, wherein, The time continuity equations for temperature and specific humidity are as follows: ； ;in, and These represent the potential temperature and specific humidity inside the boundary layer, respectively. and They represent sensible heat flux and latent heat energy at the Earth's surface, respectively. This represents the air density inside the boundary layer. Indicates specific heat at constant pressure. Indicates the height of the atmospheric boundary layer. This represents the average flow velocity at the top of the boundary layer. and These represent the temperature and specific humidity of the roll layer, respectively. Indicates a time period. It represents the latent heat of vaporization.

3. The method for estimating surface evapotranspiration according to claim 1, wherein, The degree of saturated water vapor deficit within the boundary layer The time continuity equation is as follows: ;in, Indicates time, This represents the slope of the saturated specific humidity-potential temperature curve. and They represent sensible heat flux and latent heat energy at the Earth's surface, respectively. This represents the air density inside the boundary layer. Indicates the height of the atmospheric boundary layer. Indicates the latent heat of vaporization. This represents the average flow velocity at the top of the boundary layer. Indicates specific heat at constant pressure. Indicates the potential temperature of the sandwich layer. This represents the potential temperature inside the boundary layer. Indicates the specific humidity of the sandwich layer. This indicates the specific humidity within the boundary layer.

4. The method for estimating surface evapotranspiration according to claim 1, wherein, The saturated water vapor deficit within the boundary layer With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit The expression for the relationship between the land-atmosphere coupling factor is as follows: ； ； ;in, This indicates the relative transport rate of land-atmosphere coupling. Indicates the land-atmosphere coupling time ratio. Indicates the initial saturation water vapor deficit within the atmospheric boundary layer. Indicates the winding rate, Indicates the surface transmission rate. Indicates the duration of land-atmosphere coupling. Indicates a time period.

5. The method for estimating surface evapotranspiration according to claim 1, wherein, The equation characterizing surface evapotranspiration is as follows: ； ;in, This represents the latent heat flux at the Earth's surface. and These represent net surface radiation and soil heat flux, respectively. This represents the air density inside the boundary layer. Indicates the latent heat of vaporization. This represents the hygrometer constant within the boundary layer. Indicates the surface transmission rate. Indicates the land-atmosphere coupling time ratio. This indicates the relative transport rate of land-atmosphere coupling. and These represent the sensible heat flux and the latent heat energy at the Earth's surface, respectively.

6. The method for estimating surface evapotranspiration according to claim 1, wherein, The equation for the contribution of radiation to surface evapotranspiration is as follows: ； ;in, This represents the contribution rate of the radiation term to surface evapotranspiration. Indicates the latent heat of vaporization. This represents the radiation term that affects evapotranspiration. Indicates surface evaporation. Indicates net radiation at the Earth's surface. Indicates soil heat flux, This represents the hygrometer constant within the boundary layer. This indicates the air density within the boundary layer. Indicates the latent heat of vaporization. Indicates the surface transmission rate. Indicates the land-atmosphere coupling time ratio. This indicates the relative transport rate of land-air coupling.

7. The method for estimating surface evapotranspiration according to claim 6, wherein, The equation for the contribution of the surface term to surface evapotranspiration is as follows: ； ;in, This represents the contribution rate of surface terms to surface evapotranspiration. This refers to surface parameters that affect evapotranspiration.

8. The method for estimating surface evapotranspiration according to claim 6, wherein, The equation for the atmospheric contribution to surface evapotranspiration is as follows: ； ;in, This represents the contribution rate of atmospheric terms to surface evapotranspiration. This indicates atmospheric terms that affect evapotranspiration.

9. The method for estimating surface evapotranspiration according to claim 6, wherein, The equation for the contribution of the land-atmosphere coupling term to surface evapotranspiration is as follows: ； ;in, This represents the contribution rate of the land-atmosphere coupling term to surface evapotranspiration. This indicates the land-atmosphere coupling term.

10. A surface evapotranspiration estimation device, comprising: The first equation construction module is set to derive the functional relationship between temperature and specific humidity and surface and atmospheric boundary layer top water and heat fluxes based on the boundary layer water and heat transfer theory, and construct the time continuity equation of temperature and specific humidity. The second equation construction module is set up to be based on the time continuity equation of temperature and specific humidity. Combining the relationship between saturated water vapor deficit D and temperature and specific humidity, the saturated water vapor deficit in the boundary layer is derived. The time continuity equation; The third equation construction module is set up to construct the saturated water vapor deficit within the boundary layer. The first-order nonhomogeneous ordinary differential equation was solved, and the saturated water vapor deficit in the boundary layer was obtained. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit And the relationship between land-atmosphere coupling factors; The fourth equation construction module is set to be based on the saturated water vapor deficit within the boundary layer. The time continuity equation is used to derive the relationship between surface evapotranspiration and the saturated water vapor deficit in the boundary layer. The functional relationship, combined with the surface energy balance equation and water vapor transport equation, as well as the saturated water vapor deficit within the boundary layer. With the saturated water vapor deficit of the sandwich layer Surface saturated water vapor deficit Based on the relationship between the land-atmosphere coupling factor and the land-atmosphere coupling factor, the surface evapotranspiration characterization equation under the land-atmosphere coupling effect is obtained; The fifth equation construction module is set up as a characterization equation for surface evapotranspiration based on land-atmosphere coupling. It derives equations for the contributions of radiation, surface, atmospheric, and land-atmosphere coupling terms to surface evapotranspiration, and quantifies the magnitude of the influence of land-atmosphere coupling on evapotranspiration.

11. An electronic device, comprising: At least one processor; as well as A memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the surface evapotranspiration estimation method according to any one of claims 1-9.

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