Simulation method for air temperature of lower portion of forest canopy
By using meteorological and remote sensing data to establish an energy balance model and calculate the air temperature below the forest canopy, the problems of high cost and limited coverage in existing technologies are solved, and efficient and low-cost forest microclimate simulation is achieved.
Patent Information
- Application Number
- CN202510852829.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-24
- Publication Date
- 2025-09-09
AI Technical Summary
Existing technologies for obtaining air temperature inside forest canopies are costly, time-consuming, and labor-intensive, and have limited spatial coverage, making it difficult to reflect temperature variations across the entire forest area.
By acquiring terrestrial meteorological reanalysis data and multiple remote sensing data, we established energy balance models between the atmosphere and the land surface and between the forest canopy and the soil surface, calculated the air temperature below the forest canopy, simplified the impedance network, and removed the sensible heat flux solution process between the air between the canopy and the leaves in the traditional model.
It improves computing efficiency, reduces operation and maintenance costs, expands the spatial coverage of forest microclimate simulation, and provides high-precision temperature data for the lower part of the forest canopy.
Smart Images
Figure CN120611528A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of forestry meteorology, and in particular to a method for simulating the air temperature in the lower part of a forest canopy. Background Art
[0002] Forests are the largest carbon sinks and reservoirs in terrestrial ecosystems and play a vital role in the global carbon cycle. Studying the long-term dynamics of forests under the context of climate change is of great significance for assessing the feedbacks between terrestrial ecosystems and the atmosphere. Macroclimate is the primary driver of forest ecosystem processes and has received extensive attention. It determines the function and structure of forest ecosystems by influencing tree growth rates, productivity, and the ability to survive drought conditions. However, macroclimate alone cannot fully explain the dynamic changes in forests at the local scale. Forest microclimate refers to the local environmental conditions such as temperature, radiation, humidity, and wind speed experienced by trees, which have a significant impact on forest ecosystem processes at the local scale. At the same time, microclimate is also an important measure of the cooling effect provided by forest ecosystems. Therefore, obtaining high-precision, spatially continuous microclimate data can help better understand the dynamic changes in forests under the context of global climate change and assess the function of forest ecosystems.
[0003] Air temperature within the forest canopy is a key component of the microclimate, directly influencing plant physiological processes, including regulating plant biochemical reaction rates, stomatal conductance, and evapotranspiration. Currently, the acquisition of air temperature within the canopy is mainly based on field measurements, recording data by placing temperature sensors at different heights within the canopy (from the ground to approximately 2 meters). However, this method is expensive, time-consuming, and labor-intensive, requiring significant investment in equipment procurement, installation, maintenance, and data processing. Furthermore, this method has limited spatial coverage, providing measurement data only at a limited number of locations, making it difficult to reflect temperature variations within the canopy across the entire forest area. Summary of the Invention
[0004] The purpose of the present invention is to provide a method for simulating the air temperature in the lower part of a forest canopy, which is used to comprehensively analyze the temperature and its changes in the lower part of the forest canopy.
[0005] In order to achieve the above object, the present invention provides the following technical solutions: A method for simulating air temperature below a forest canopy, comprising: Obtain land meteorological reanalysis data and multiple remote sensing data to determine the forest data that needs to be analyzed; Establish an energy balance model between the atmosphere and the surface, use the land meteorological reanalysis data and multiple remote sensing data as input to solve the energy balance model between the atmosphere and the surface, and obtain the air temperature between the canopy layers. T ac ; The surface is divided into two layers: the forest canopy and the soil surface. An energy balance model between the forest canopy and the soil surface is established. The air temperature between the canopies and multiple remote sensing data are used as input to solve the energy balance model between the forest canopy and the soil surface. The air temperature under the forest canopy is obtained. T af .
[0006] A further technical solution is that the land meteorological reanalysis data includes the air temperature on the surface, the dew point temperature on the surface, the wind speed on the surface, and the surface sensible heat flux; the multi-remote sensing data includes annual tree height data, monthly average leaf area index, altitude data, and annual land cover type data.
[0007] A further technical solution is that the establishment of the energy balance model between the atmosphere and the surface includes: establishing a wind speed correction equation, an atmosphere-canopy impedance coefficient calculation equation, and an air temperature calculation equation between canopies.
[0008] A further technical solution is to use the land meteorological reanalysis data and multiple remote sensing data as input to solve the energy balance model between the atmosphere and the surface to obtain the air temperature between the canopies, specifically including: The wind speed above the ground is brought into the wind speed correction equation to calculate the corrected wind speed u z ; The corrected wind speed u z , the air temperature above the ground surface and multiple remote sensing data are brought into the atmosphere-canopy impedance coefficient calculation equation to calculate the atmosphere-canopy impedance coefficient; The atmosphere-canopy impedance coefficient, the air temperature above the ground surface, and the ground surface sensible heat flux are introduced into the air temperature calculation equation between the canopies to calculate the air temperature between the canopies.
[0009] A further technical solution is that the energy balance model between the forest canopy and the soil surface is established, including: establishing a NicheMapR model, establishing a canopy-soil impedance coefficient calculation equation, establishing a calculation equation for the sensible heat flux of air temperature between the soil surface and the canopy, and establishing an equation for calculating the air temperature under the canopy.
[0010] A further technical solution is to use the air temperature between the canopy and multiple remote sensing data as input to solve the energy balance model between the forest canopy and the soil surface to obtain the air temperature under the forest canopy, specifically including: The land meteorological reanalysis data is brought into the NicheMapR model for calculation to obtain the soil surface temperature; The canopy-soil impedance coefficient is calculated according to the canopy-soil impedance coefficient calculation equation; Substituting the soil surface temperature, the air temperature between canopies and the canopy-soil impedance coefficient into the calculation equation of the air temperature sensible heat flux between soil and canopy, the sensible heat flux from the soil surface to the air temperature between canopy is calculated; The canopy-soil impedance coefficient is decomposed to obtain the impedance coefficient at a specific height; the impedance coefficient at the specific height, the sensible heat flux of the air temperature from the soil surface to the canopy, and the air temperature between the canopies are substituted into the air temperature calculation equation under the canopy to calculate the air temperature under the canopy.
[0011] A further technical solution is that the air temperature under the forest canopy is obtained T af Then, it also includes: If the air temperature under the forest canopy T af Below the dew point temperature on the ground T dw , then adjust the air temperature under the forest canopy to be equal to the dew point temperature above the ground surface; compare the air temperature under the forest canopy with the air temperature above the ground surface to obtain the temperature deviation between inside and outside the forest.
[0012] Compared with the prior art, the method for simulating the air temperature below the forest canopy provided by the present invention has the following beneficial effects: This method focuses on calculating the air temperature under the canopy by simplifying the impedance network between the tube layers. T af , obtain the sensible heat flux from the surface to the atmosphere from the meteorological analysis dataset H , removing the sensible heat flux between the canopy air and leaves in the traditional SiB2 model H c The solution process improves computational efficiency and expands the traditional theoretical framework to support the simulation of forest microclimate. There is no need to purchase equipment for installation and maintenance, which reduces operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 A flow chart of a method provided by an embodiment of the present invention; Figure 2 A flowchart for solving the energy balance model between the atmosphere and the Earth's surface according to an embodiment of the present invention; Figure 3 A flowchart for solving the energy balance model between the forest canopy and the soil surface according to an embodiment of the present invention; Figure 4 This is a diagram of the accuracy verification results provided in an embodiment of the present invention; Figure 5 The figure shows the spatial distribution of understory temperature in Europe in different months simulated using the method of the present invention. DETAILED DESCRIPTION
[0014] To facilitate a clear description of the technical solutions of the embodiments of the present invention, the words "first" and "second" are used in the embodiments of the present invention to distinguish between identical or similar items with substantially the same functions and effects. For example, the first threshold and the second threshold are merely used to distinguish between different thresholds and do not limit their order. Those skilled in the art will understand that the words "first" and "second" do not limit the quantity or execution order, and the words "first" and "second" do not necessarily mean different.
[0015] It should be noted that, in the present invention, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present invention should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.
[0016] The embodiment of the present invention provides a method for simulating the air temperature below the forest canopy, including the following steps. Figure 1 : Step S1: Obtain land meteorological reanalysis data and multiple remote sensing data to determine the forest data that needs to be analyzed.
[0017] Land meteorological reanalysis data, provided by the European Centre for Medium-Range Weather Forecasts (ECMWF), includes surface air temperature, surface dew point temperature, surface wind speed, and surface heat flux. Multi-remote sensing data includes a global tree height product, a global leaf area index product, a global digital elevation model product, and a land cover type product. Both land meteorological reanalysis data and multi-remote sensing data are publicly available.
[0018] Step S2: Establish an energy balance model between the atmosphere and the surface, use the land meteorological reanalysis data and multi-remote sensing data as input to solve the energy balance model between the atmosphere and the surface, and obtain the air temperature between the canopy layers. T ac .
[0019] Among them, the energy balance model between the atmosphere and the surface is established, including: establishing a wind speed correction equation, an atmosphere-canopy impedance coefficient calculation equation, and an air temperature calculation equation between the canopies.
[0020] Solving the energy balance model between the atmosphere and the surface includes the following steps. Figure 2 : Step S21: Substitute the wind speed above the ground surface into the wind speed correction equation to calculate the corrected wind speed u z .
[0021] Since the surface air temperature in the land meteorological reanalysis data is the temperature at 2m above the surface, and the surface wind speed is the wind speed at 10m above the surface, it is necessary to convert it into the wind speed at 2m above the surface for unified calculation. u z Calculated by the following formula: ; Where, u z represents the wind speed at height z above the canopy (m / s); u m Indicates the measured height is z m Wind speed at (m / s); is the adiabatic correction factor for the wind speed profile (under neutral atmospheric conditions, is 0); d It represents the zero plane displacement height, which is the average height at which momentum transfer occurs between airflow and forest, and is usually 2 / 3 of the forest canopy height.
[0022] Step S22: Correcting the wind speed u z , surface air temperature and multiple remote sensing data are brought into the atmosphere-canopy impedance coefficient calculation equation to calculate the atmosphere-canopy impedance coefficient r a , expressed by the following formula: ; Where, r a The impedance coefficient of heat and water vapor exchange between the air between the canopy and the atmosphere above the canopy by turbulent transmission; z 0M is the aerodynamic roughness length, which represents the height above the surface at which the wind speed outside the canopy decays to 0 m / s according to the logarithmic wind profile; z 0H is the thermal roughness length, which indicates the turbulent efficiency of surface heat transfer. The air temperature changes with height, z 0H is the height of the air above the surface when the surface air temperature is equal to the surface temperature; is the adiabatic correction factor; d It represents the zero plane displacement height, which is the average height at which momentum transfer occurs between airflow and forest.
[0023] Step S23: Substitute the atmosphere-canopy impedance coefficient, the air temperature above the ground surface, and the ground surface sensible heat flux into the air temperature calculation equation between the canopies to calculate the air temperature between the canopies, which is expressed by the following formula: ; Where, T ac represents the intercanopy air temperature; T a Represents the air temperature data outside the canopy; H represents the surface sensible heat flux; ρ Indicates air density (kg / m 3 ); C p It represents the specific heat capacity of air at constant pressure (J / kg / K).
[0024] Step S3: Split the ground surface into two layers: the forest canopy and the soil surface, establish an energy balance model between the forest canopy and the soil surface, and use the air temperature between the canopies and multiple remote sensing data as input to solve the energy balance model between the forest canopy and the soil surface to obtain the air temperature under the forest canopy. T af .
[0025] The energy balance model between the forest canopy and the soil surface was established, including the NicheMapR model, equations for calculating the canopy-soil impedance coefficient, equations for calculating the sensible heat flux between the soil surface and the canopy, and equations for calculating the air temperature below the canopy. The NicheMapR model is a software package for mechanistic niche modeling that integrates methods from biophysical ecology, environmental biophysics, and metabolic theory, primarily for use in the R programming environment.
[0026] Solving the energy balance model between the forest canopy and the soil surface involves the following steps. Figure 3 : Step S31: Build a NicheMapR model and apply the land meteorological reanalysis data to the NicheMapR model to calculate soil surface temperature. Based on the principles of surface energy balance and heat conduction, the NicheMapR model can predict temperature changes at different depths within the soil. Its input data is obtained from the land meteorological reanalysis data.
[0027] Input data include air temperature, surface air pressure, solar radiation, total precipitation, cloud cover, wind speed, minimum shade, slope, and orientation. Meteorological data comes from land meteorological reanalysis data, and terrain-related data comes from multi-source remote sensing data.
[0028] Step S32: Establish a canopy-soil impedance coefficient calculation equation, bring the multiple remote sensing data into the canopy-soil impedance coefficient calculation equation, and calculate the canopy-soil impedance coefficient r d , expressed by the following formula: ; Where, r d is the resistance coefficient of heat and water vapor exchange between the forest canopy and the soil surface relying on turbulent transport; c s represents the turbulent transport coefficient, which is weighted by the contributions of soil and dense canopy; u * Represents the friction velocity of the fluid passing over the canopy.
[0029] Both canopy and soil turbulence contribute to impedance, with the canopy contribution primarily influenced by leaf area index and height, a coefficient that varies with both components.
[0030] Step S33: Establish a calculation equation for the air temperature sensible heat flux between the soil surface and the canopy, and bring the soil surface temperature, the air temperature between the canopy and the canopy-soil impedance coefficient into the calculation equation for the air temperature sensible heat flux between the soil surface and the canopy to calculate the air temperature sensible heat flux between the soil surface and the canopy. H s , expressed by the following formula: ; Where, T ac represents the air temperature between canopies, T s represents the soil surface temperature, ρ Indicates the air density; C p It represents the specific heat capacity of air at constant pressure.
[0031] Step S34: The canopy-soil impedance coefficient r d Disassemble and obtain the impedance coefficient at a specific height r d2 .
[0032] The specific height is 2 meters above the ground and below the canopy. To calculate the air temperature at this specific height, the impedance coefficient must first be decomposed. To improve computational efficiency, the complex structure of the understory, such as shrubs and herbs, is simplified. It is assumed that the momentum transfer coefficient from the soil surface to the equivalent height of the forest canopy is constant, and the impedance coefficient varies linearly with height: ; ; r d is the total impedance coefficient, r d1 and r d2 The impedance coefficient is divided into two parts, 0-2m and 2m-d, based on the 2m ground surface line. Since we calculate it by the canopy temperature, the air temperature at the height of 2m below the canopy is selected. r d2 .
[0033] Step S35: Calculate the air temperature under the canopy by using the impedance coefficient at a specific height r d2 , air temperature between canopies T ac and the thermal flux from the soil surface to the air temperature of the canopy H s Substitute into the air temperature calculation equation under the canopy to calculate the air temperature under the canopy T af , expressed by the following formula: ; Where, T ac represents the air temperature within the forest canopy, H s The heat flux represents the air temperature from the soil surface to the forest canopy; ρ Indicates the air density; C p It represents the specific heat capacity of air at constant pressure; r d2 It represents the impedance coefficient 2 meters below the ground surface under the canopy.
[0034] Step S4: If the air temperature under the forest canopy T af Below the dew point temperature above the surface T dw , then the air temperature under the forest canopy is adjusted to be equal to the dew point temperature above the ground surface; the air temperature under the forest canopy is compared with the air temperature above the ground surface to obtain the deviation of the temperature inside and outside the forest, which is expressed by the following formula: ; Where, T ac represents the air temperature within the forest canopy, T a is the surface air temperature, T offset Represents the difference in air temperature between inside and outside the forest.
[0035] If the air temperature under the forest canopy T af Not lower than the dew point temperature above the ground T dw , then the current air temperature under the forest canopy is still calculated T af Calculate the temperature deviation inside and outside the forest.
[0036] This method focuses on calculating the air temperature under the canopy by simplifying the impedance network between the tube layers. T af , obtain the sensible heat flux from the surface to the atmosphere from the meteorological analysis dataset H , removing the sensible heat flux between the canopy air and leaves in the traditional SiB2 model H c The solution process improves the computational efficiency and expands the traditional theoretical framework to support the simulation of forest microclimate. like Figure 4 As shown in the figure, this example collects in-forest temperature data and temperature deviation data from inside and outside forests from sample sites across the globe, covering different forest types and climate zones. A total of 896 in-forest temperature data are collected, covering the period from 1984 to 2021. The data include (a) study site distribution, (b) simulation frequency, (c) simulated in-forest temperature effects, and (d) time series comparisons. The data were aggregated using the Python programming language, averaged monthly, and compared with the results simulated by this method. Simulation results were also compared with the time series results from monitoring sites at the Smithsonian Institution's Environmental Research Center.
[0037] like Figure 5 As shown, this example uses the collected meteorological reanalysis data from 2000 to 2020, canopy structure parameters, terrain factors, and forest type parameters as input, and generates the average forest internal temperature data for February, May, August, and November in a 15°×15° area in Europe based on this method.
[0038] Although the present invention has been described with reference to specific features and embodiments thereof, it will be apparent that various modifications and combinations may be made thereto without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely illustrative of the invention as defined by the appended claims and are deemed to cover any and all modifications, variations, combinations or equivalents within the scope of the invention. It will be apparent that various modifications and variations may be made to the present invention by those skilled in the art without departing from the spirit and scope of the invention. Thus, the present invention is intended to include such modifications and variations as fall within the scope of the claims of the present invention and their equivalents.
Claims
1. A method for simulating air temperature below a forest canopy, characterized in that: include: Obtain land meteorological reanalysis data and multiple remote sensing data to determine the forest data that needs to be analyzed; Establish an energy balance model between the atmosphere and the surface, use the land meteorological reanalysis data and multiple remote sensing data as input to solve the energy balance model between the atmosphere and the surface, and obtain the air temperature between the canopy layers. T ac ; The surface is divided into two layers: the forest canopy and the soil surface. An energy balance model between the forest canopy and the soil surface is established. The air temperature between the canopies and multiple remote sensing data are used as input to solve the energy balance model between the forest canopy and the soil surface. The air temperature under the forest canopy is obtained. T af .
2. The method for simulating air temperature below a forest canopy according to claim 1, characterized in that: The land meteorological reanalysis data includes the air temperature on the surface, the dew point temperature on the surface, the wind speed on the surface, and the surface sensible heat flux; the multi-remote sensing data includes annual tree height data, monthly average leaf area index, altitude data, and annual land cover type data.
3. The method for simulating air temperature below a forest canopy according to claim 2, characterized in that: The energy balance model between the atmosphere and the ground surface is established, which includes establishing a wind speed correction equation, an atmosphere-canopy impedance coefficient calculation equation, and an air temperature calculation equation between canopies.
4. The method for simulating air temperature below a forest canopy according to claim 3, characterized in that: The method of using the land meteorological reanalysis data and the multi-remote sensing data as input to solve the energy balance model between the atmosphere and the surface to obtain the air temperature between the canopies specifically includes: The wind speed above the ground is brought into the wind speed correction equation to calculate the corrected wind speed u z ; The corrected wind speed u z , the air temperature above the ground surface and multiple remote sensing data are brought into the atmosphere-canopy impedance coefficient calculation equation to calculate the atmosphere-canopy impedance coefficient; The atmosphere-canopy impedance coefficient, the air temperature above the ground surface, and the ground surface sensible heat flux are introduced into the air temperature calculation equation between the canopies to calculate the air temperature between the canopies.
5. The method for simulating air temperature below a forest canopy according to claim 1, characterized in that: The energy balance model between the forest canopy and the soil surface is established, including: establishing a NicheMapR model, establishing a canopy-soil impedance coefficient calculation equation, establishing a soil surface-canopy air temperature sensible heat flux calculation equation, and establishing an under-canopy air temperature calculation equation.
6. The method for simulating air temperature below a forest canopy according to claim 5, characterized in that: The method of using the air temperature between the canopy layers and multiple remote sensing data as input to solve the energy balance model between the forest canopy layer and the soil surface to obtain the air temperature under the forest canopy layer specifically includes: The land meteorological reanalysis data is brought into the NicheMapR model for calculation to obtain the soil surface temperature; The canopy-soil impedance coefficient is calculated according to the canopy-soil impedance coefficient calculation equation; Substituting the soil surface temperature, the air temperature between canopies and the canopy-soil impedance coefficient into the calculation equation of the air temperature sensible heat flux between soil and canopy, the sensible heat flux from the soil surface to the air temperature between canopy is calculated; The canopy-soil impedance coefficient is decomposed to obtain the impedance coefficient at a specific height; the impedance coefficient at the specific height, the sensible heat flux of the air temperature from the soil surface to the canopy, and the air temperature between the canopies are substituted into the air temperature calculation equation under the canopy to calculate the air temperature under the canopy.
7. The method for simulating air temperature below a forest canopy according to claim 1, characterized in that: The air temperature under the forest canopy is obtained by T af Then, it also includes: If the air temperature under the forest canopy T af Below the dew point temperature on the ground T dw , then adjust the air temperature under the forest canopy to be equal to the dew point temperature above the ground surface; compare the air temperature under the forest canopy with the air temperature above the ground surface to obtain the temperature deviation between inside and outside the forest.