A terrain correction method for surface radiation in mountainous areas

Abstract

The present application belongs to the technical field of remote sensing data processing, and specifically relates to a terrain correction method for surface radiation in mountainous areas, including: S10, obtaining plane surface radiation data of the same period, wherein the plane surface radiation data includes short-wave radiation data and / or long-wave radiation data of the plane surface; S20, inputting the plane surface radiation data into a pre-established mountainous area radiation correction model to obtain the mountainous area surface radiation; wherein the mountainous area radiation correction model is a mathematical model that outputs the mountainous area surface radiation after correcting the plane surface radiation by a preset radiation correction coefficient; the radiation correction coefficient is determined based on the pixel area and the corresponding mountainous area surface. Correcting the mountainous area radiation by the correction method of the present application not only has a small amount of calculation and high efficiency, but also the radiation correction result obtained is more accurate.

Description

Technical Field

[0001] The present application belongs to the technical field of remote sensing data processing, and specifically relates to a terrain correction method for surface radiation in mountainous areas. Background Art

[0002] Shortwave radiation and longwave radiation are important foundations for the energy balance of the Earth system, affecting the global energy and water cycle and even global change.

[0003] With the development of remote sensing technology, it has become possible to use remote sensing data to estimate shortwave and longwave radiation on a global scale with high precision, and many satellite programs have released related radiation products. However, almost all publicly released products do not take into account the impact of terrain. Many studies have shown that mountainous areas, which account for nearly 20% of the global coverage area, have a significant impact on shortwave and longwave radiation, which cannot be ignored even at a scale of 10 km.

[0004] Among the existing terrain correction methods, there are methods that perform correction at the scale of Digital Elevation Model (DEM), which has a very large amount of calculation; there are methods that directly calculate parameters such as slope and aspect at the remote sensing scale. This method directly uses pixels as large-scale DEM, resulting in many terrain details being smoothed.

[0005] In summary, the existing terrain correction methods are difficult to meet the needs of accurate and efficient terrain correction of radiation in mountainous areas. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present application provides a terrain correction method for surface radiation in mountainous areas.

[0008] (II) Technical solution

[0009] In order to achieve the above objectives, this application adopts the following technical solutions:

[0010] In a first aspect, an embodiment of the present application provides a terrain correction method for surface radiation in a mountainous area, the method comprising:

[0011] S10, acquiring plane surface radiation data of the same period, wherein the plane surface radiation data includes short-wave radiation data and / or long-wave radiation data of the plane surface;

[0012] S20, inputting the plane surface radiation data into a pre-established mountain area radiation correction model to obtain the mountain area surface radiation;

[0013] The mountain radiation correction model is a mathematical model that outputs the mountain surface radiation after correcting the plane surface radiation through a preset radiation correction coefficient; the radiation correction coefficient is determined based on the pixel area and its corresponding mountain surface area.

[0014] Optionally, when the surface radiation in the mountainous area is the long-wave downward radiation in the mountainous area, the mountainous area radiation correction model is expressed as:

[0015]

[0016] Among them, F rugged_LW is the longwave downward radiation from the mountain surface, F LW is the long-wave radiation from the flat surface, S p is the pixel area, S rugged is the surface area of ​​the pixel, F emi It is the long-wave radiation contribution of the surrounding terrain to the target pixel.

[0017] Optionally, when the surface radiation in the mountain area is the shortwave downlink radiation in the mountain area, the plane surface radiation data is the shortwave radiation data of the plane surface, and the shortwave radiation data includes direct shortwave radiation data, scattered shortwave radiation data, and surrounding terrain reflected radiation data;

[0018] The mountain area radiation correction model also corrects the direct radiation of the plane surface through a preset direct radiation correction coefficient; the direct radiation correction coefficient is determined based on the solar illumination angle and the solar zenith angle.

[0019] Optionally, when the surface radiation in the mountainous area is the shortwave downlink radiation in the mountainous area, the mountainous area radiation correction model is expressed as:

[0020]

[0021] Among them, F rugged is the shortwave downward radiation from the mountain surface, F d is the direct shortwave radiation from the flat surface, F s is the scattered shortwave radiation from the flat surface, S p is the pixel area, S rugged is the pixel surface area, F ref is the reflected radiation data of the surrounding terrain to the target pixel, Θ and μ are the equivalent values ​​of the cosine of the solar illumination angle and the solar zenith angle, respectively.

[0022] Optionally, before S10, the method further includes:

[0023] Get DEM data;

[0024] Calculate DEM terrain parameters of the mountain area using DEM data, wherein the DEM terrain parameters include slope, aspect, and sky visibility factor;

[0025] The solar illumination angle and the solar zenith angle are calculated based on the DEM terrain parameters and the solar angle.

[0026] Optionally, the plane surface radiation data is one of instantaneous data, daily average value, and monthly average value.

[0027] Optionally, the plane surface radiation data is one of remote sensing data, reanalysis data, and simulation data.

[0028] Optionally, the pixel area is a remote sensing pixel area or a pixel area in reanalyzed radiation data.

[0029] (III) Beneficial effects

[0030] The beneficial effects of the present application are as follows: the present application proposes a terrain correction method for surface radiation in mountainous areas, wherein the method comprises: S10, obtaining plane surface radiation data of the same period, wherein the plane surface radiation data comprises short-wave radiation data and / or long-wave radiation data of the plane surface; S20, inputting the plane surface radiation data into a pre-established mountainous area radiation correction model to obtain the mountainous area surface radiation; wherein the mountainous area radiation correction model is a mathematical model that outputs the mountainous area surface radiation after correcting the plane surface radiation by a preset radiation correction coefficient; the radiation correction coefficient is determined based on the pixel area and the corresponding mountainous area surface area. The correction method of the present application corrects the mountainous area radiation by using a radiation correction coefficient determined based on the pixel area and the mountainous area surface area, which not only has a small amount of calculation and high efficiency, but also has a more accurate radiation correction result. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present application is described with the aid of the following drawings:

[0032] Figure 1 This is a flow chart of a terrain correction method for surface radiation in a mountainous area in one embodiment of the present application;

[0033] Figure 2 It is a schematic flow chart of a terrain correction method for long- and short-wave radiation on a mountain surface in another embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below in conjunction with the accompanying drawings through specific implementation methods. It is understood that the specific embodiments described below are only used to explain the relevant inventions, rather than to limit the invention. It should also be noted that the embodiments and features in the embodiments of this application can be combined with each other in the absence of conflict; for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0035] The present application proposes a terrain correction method for surface radiation in mountainous areas, and the present application is described in detail through embodiments below.

[0036] Embodiment 1

[0037] Figure 1 FIG. 1 is a flow chart of a terrain correction method for surface radiation in a mountainous area in one embodiment of the present application. Figure 1 As shown, the terrain correction method for surface radiation in mountainous areas of this embodiment includes:

[0038] S10, acquiring plane surface radiation data of the same period, where the plane surface radiation data includes short-wave radiation data and / or long-wave radiation data of the plane surface;

[0039] S20, inputting the plane surface radiation data into a pre-established mountain area radiation correction model to obtain the mountain area surface radiation;

[0040] Among them, the mountain radiation correction model is a mathematical model that outputs the mountain surface radiation after correcting the plane surface radiation through a preset radiation correction coefficient; the radiation correction coefficient is determined based on the pixel area and its corresponding mountain surface area.

[0041] The terrain correction method for surface radiation in mountainous areas in this embodiment is different from the previous terrain correction ideas. It directly starts from the perspective of energy conservation to achieve terrain correction of radiation in mountainous areas. It not only has a small amount of calculation and high efficiency, but also obtains more accurate radiation correction results, thereby realizing fast and high-precision terrain correction of short-wave radiation and long-wave radiation in complex terrain areas on a global scale.

[0042] In order to better understand the present invention, each step in this embodiment is described below.

[0043] In S10 of this embodiment, the plane surface radiation data includes short-wave radiation data and / or long-wave radiation data of the plane surface. The source of the acquired plane surface radiation data may be remote sensing data of mountain terrain obtained from corresponding products estimated from various types of satellite remote sensing data, or mountain radiation data extracted from various types of reanalysis radiation data, or radiation data obtained from simulation data. This embodiment does not specifically limit the data source.

[0044] The shortwave radiation and longwave radiation here also include their various components, such as shortwave downward radiation, photosynthetically active radiation, shortwave net radiation, longwave downward radiation, longwave upward radiation, longwave net radiation, etc.

[0045] In this embodiment, the plane surface radiation data may be one of instantaneous data, daily average value, and monthly average value. This embodiment does not specifically limit the form and scale of the data.

[0046] In S20 of this embodiment, the pixel area is the remote sensing pixel area or the pixel area in the reanalysis radiation data or simulation data; the corresponding mountain surface area is the surface area of ​​the pixel, which can be obtained by dividing the plane area of ​​each DEM grid in the pixel by the corresponding slope and then performing cumulative calculation.

[0047] In S20 of this embodiment, when the surface radiation in the mountainous area is the long-wave downward radiation in the mountainous area, the radiation correction model in the mountainous area is expressed as formula (1):

[0048]

[0049] Among them, F rugged_LW is the longwave downward radiation from the mountain surface, F LW is the long-wave radiation from the flat surface, S p is the pixel area, S rugged is the surface area of ​​the pixel, F emi It is the long-wave radiation contribution of the surrounding terrain to the target pixel.

[0050] Here, the long-wave radiation contribution of the surrounding terrain to the target pixel refers to the part of the thermal radiation emitted by the surrounding terrain itself and received by the target pixel, which can be approximately estimated by the upward radiation of the surrounding terrain or calculated by using the surface temperature and emissivity of the surrounding terrain in combination with Boltzmann's law; it can also be estimated by referring to other methods for calculating the short-wave radiation of the surrounding terrain in existing studies, which will not be described in detail in this embodiment.

[0051] In this embodiment, when the surface radiation in the mountainous area is the shortwave downlink radiation in the mountainous area, the plane surface radiation data is the shortwave radiation data of the plane surface. Specifically, the shortwave radiation data includes direct shortwave radiation data, scattered shortwave radiation data, and surrounding terrain reflected radiation data.

[0052] The mountain radiation correction model also corrects the direct radiation of the flat surface through a preset direct radiation correction coefficient; the direct radiation correction coefficient is determined based on the solar illumination angle and the solar zenith angle.

[0053] In this embodiment, when the surface radiation in the mountainous area is the shortwave downlink radiation in the mountainous area, the mountainous area radiation correction model is expressed as formula (2):

[0054]

[0055] Among them, F rugged is the shortwave downward radiation from the mountain surface, F d is the direct shortwave radiation from the flat surface, F s is the scattered shortwave radiation from the flat surface, S p is the pixel area, S rugged is the pixel surface area, F ref is the reflected radiation data of the surrounding terrain to the target pixel, Θ and μ are the cosine values ​​of the solar illumination angle and the solar zenith angle, respectively.

[0056] Here, the reflected radiation data of the surrounding terrain to the target pixel can be estimated by referring to the existing method, which will not be described in detail in this embodiment. The solar illumination angle and the solar zenith angle cosine value are calculated from the solar illumination angle and the solar zenith angle at the time of obtaining the plane surface radiation data.

[0057] This embodiment proposes a method for fast and high-precision terrain correction of short-wave radiation and long-wave radiation, which is completely different from the existing radiation terrain correction method. It introduces the ratio of the pixel area and its corresponding complex mountain surface area, and establishes a new correction model from the perspective of energy conservation. When correcting short-wave radiation, the ratio of the average illumination angle and the cosine of the solar zenith angle is introduced, and the direct and scattered short-wave radiation are modeled respectively; thereby improving the accuracy and efficiency of the correction.

[0058] The input data in this method does not refer to a specific type of data. The technology and model of terrain correction are universal, so it can be applied to mountainous areas in different regions of the world and has a wide range of applicability.

[0059] Embodiment 2

[0060] The execution subject of this embodiment may be a remote sensing detection system, which may include a memory and a processor. In some other embodiments, the execution subject may also be other electronic devices that can achieve the same or similar functions, which is not limited in this embodiment.

[0061] Figure 2 This is a flow chart of a terrain correction method for long- and short-wave radiation on the mountain surface in another embodiment of the present application. Based on the first embodiment, this embodiment describes in detail the specific implementation process of this embodiment. Figure 2 The steps of the method in this embodiment are described in detail.

[0062] S1. Obtain DEM elevation data. DEM is a digital simulation of the terrain surface created based on the terrain elevation data.

[0063] S2. Use DEM elevation data to calculate DEM terrain parameters in mountainous areas. DEM terrain parameters include slope, aspect, sky visibility factor, and aspect surface area at the DEM scale. Calculate the solar illumination angle and solar zenith angle based on DEM terrain parameters and sun angle.

[0064] Specifically, the DEM data is used to calculate the elevation change rate in the east-west and north-south directions, thereby obtaining the slope value of the DEM scale. The solar illumination angle and solar zenith angle can be read from the remote sensing image metafile. The DEM scale here is usually 90m or 30m, which is smaller than the scale of satellite pixels.

[0065] It should be noted that, in some other embodiments, the required DEM elevation data may be published by other organizations or obtained by field measurements, and this embodiment does not specifically limit this.

[0066] S3. Acquire longwave radiation data and shortwave radiation data, where the shortwave radiation data includes direct shortwave radiation data and scattered shortwave radiation data.

[0067] S4. Input the long-wave radiation data and the short-wave radiation data into a pre-established short-wave radiation correction model and a long-wave radiation correction model; wherein the short-wave radiation correction model is as shown in formula (1) in Example 1, and the long-wave radiation correction model is as shown in formula (2) in Example 1, which will not be described in detail here.

[0068] S5, performing pixel-by-pixel correction on the long-wave radiation data and the short-wave radiation data;

[0069] S6. Generate terrain-corrected shortwave radiation and longwave radiation.

[0070] In this embodiment, by combining the terrain parameters of DEM and inputting the corresponding plane surface shortwave radiation (direct, scattered) and longwave radiation into formulas (1) and (2), terrain correction of shortwave radiation and longwave radiation from various sources can be achieved, meeting the demand for accurate and efficient terrain correction of radiation in mountainous areas. The method of this embodiment can be applied to various fields such as global change, research on energy and water cycle in mountainous areas, evapotranspiration estimation, ice and snow melting, hydrological simulation and water resources management, solar photovoltaic power generation, and vegetation photosynthesis.

[0071] It should be noted that in the claims, any reference signs placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention may be implemented by means of hardware comprising several distinct components and by means of a suitably programmed computer. The use of the words first, second, third, etc., is for convenience of expression only and does not imply any order. These words may be understood as part of the component name.

[0072] In addition, it should be noted that, in the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0073] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments after knowing the basic creative concept. Therefore, the claims should be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0074] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention should also include these modifications and variations.

Claims

1. A terrain correction method for surface radiation in mountainous areas, characterized in that: The method includes: S10, acquiring plane surface radiation data of the same period, wherein the plane surface radiation data includes short-wave radiation data and / or long-wave radiation data of the plane surface; S20, inputting the plane surface radiation data into a pre-established mountain area radiation correction model to obtain the mountain area surface radiation; The mountain radiation correction model is a mathematical model that outputs the mountain surface radiation after correcting the plane surface radiation by a preset radiation correction coefficient; the radiation correction coefficient is determined based on the pixel area and its corresponding mountain surface area; the mountain surface area is the surface area of ​​the pixel, which is obtained by dividing the plane area of ​​each DEM grid in the pixel by the corresponding slope and then accumulating and calculating; The pixel area is the remote sensing pixel area or the pixel area in the reanalysis radiation data; When the surface radiation in mountainous areas is the long-wave downward radiation in mountainous areas, the mountainous area radiation correction model is expressed as: Among them, F rugged_LW is the longwave downward radiation from the mountain surface, F LW is the long-wave radiation from the flat surface, S p is the pixel area, S rugged is the surface area of ​​the pixel, F emi is the long-wave radiation contribution of the surrounding terrain to the target pixel; When the surface radiation in mountainous areas is the shortwave downlink radiation in mountainous areas, the mountainous area radiation correction model is expressed as: Among them, F rugged is the shortwave downward radiation from the mountain surface, F d is the direct shortwave radiation from the flat surface, Fs is the scattered shortwave radiation from the flat surface, S p is the pixel area, S rugged is the pixel surface area, F ref is the reflected radiation data of the surrounding terrain to the target pixel, Θ and μ are the equivalent values ​​of the cosine of the solar illumination angle and the solar zenith angle, respectively.

2. The terrain correction method for surface radiation in mountainous areas according to claim 1, characterized in that: When the surface radiation in the mountainous area is the shortwave downlink radiation in the mountainous area, the plane surface radiation data is the shortwave radiation data of the plane surface, and the shortwave radiation data includes direct shortwave radiation data, scattered shortwave radiation data, and surrounding terrain reflected radiation data; The mountain area radiation correction model also corrects the direct radiation of the plane surface through a preset direct radiation correction coefficient; the direct radiation correction coefficient is determined based on the solar illumination angle and the solar zenith angle.

3. The terrain correction method for surface radiation in mountainous areas according to claim 2, characterized in that: Prior to S10, this also included: Get DEM data; Calculate DEM terrain parameters of the mountain area using DEM data, wherein the DEM terrain parameters include slope, aspect, and sky visibility factor; The solar illumination angle and the solar zenith angle are calculated based on the DEM terrain parameters and the solar angle.

4. The terrain correction method for surface radiation in mountainous areas according to claim 1, characterized in that: The plane surface radiation data is one of instantaneous data, daily average value and monthly average value.

5. The terrain correction method for surface radiation in mountainous areas according to claim 1, characterized in that: The plane surface radiation data is one of remote sensing data, reanalysis data, and simulation data.

Images