Method for constructing complex terrain static meteorological satellite brightness temperature variational assimilation observation operator

Abstract

The application discloses a complex terrain geostationary meteorological satellite brightness temperature variational assimilation observation operator construction method, which comprises the following steps: considering the sub-pixel terrain radiation effect, introducing a sub-pixel terrain correction parameter into a ground surface radiation item of a CRTM radiation transfer model to construct a forward operator of a complex terrain ground surface radiation item; linearizing the complex terrain ground surface radiation item containing the sub-pixel terrain correction parameter to establish a tangent linear operator of the complex terrain ground surface radiation item; performing an adjoint transposition on the tangent linear operator to establish an adjoint operator of the complex terrain ground surface radiation item; and coupling the forward observation operator, the tangent linear operator and the adjoint operator to corresponding modules of the CRTM radiation transfer model respectively to serve as a complex terrain geostationary meteorological satellite brightness temperature variational assimilation observation operator. The application can effectively improve the variational assimilation level of geostationary meteorological satellite infrared brightness temperature data, especially in complex undulating terrain areas.

Description

Technical Field

[0001] This invention relates to the field of atmospheric science research, specifically to a method for constructing brightness temperature variational assimilation observation operators for geostationary meteorological satellites in complex terrain. Background Technology

[0002] With the development of numerical models and observation techniques, data assimilation from geostationary meteorological satellites has played a crucial role in numerical weather prediction. New-generation geostationary meteorological satellites offer high spatial and temporal resolution. However, satellite data assimilation techniques still require significant improvement, particularly in cloud-affected areas and overland regions.

[0003] Assimilation of geostationary satellite data over land is crucial for forecasting severe convection and other weather events. Before convection is triggered, infrared brightness temperatures observed in surface-sensitive channels can capture information on lower atmospheric stability and water vapor levels. These channels typically contain three weighted functions at 8.60 µm, 10.8 µm, and 12 µm, corresponding to satellite channel numbers 11, 12, and 13, respectively. However, assimilating satellite data over land remains extremely challenging due to technological limitations. The accuracy of background surface temperature and surface emissivity is generally critical for surface-sensitive brightness temperature simulations, as they are two important input parameters in radiative transfer models (RTMs). Furthermore, complex terrain presents additional challenges to near-surface radiative transfer simulations compared to flat terrain, a key obstacle hindering satellite brightness temperature assimilation.

[0004] Developing satellite assimilation techniques for complex terrain regions is urgently needed, as these areas are often associated with the triggering of severe convective weather. However, the brightness temperature difference between observations and the background is typically greater in topographic regions than in flat areas. Previous studies have performed quality control based on the standard deviation of topographic elevation before assimilating satellite radiative data. However, in addition to the typical problems encountered in flat areas regarding surface temperature and surface emissivity, current fast radiative transfer models also face limitations due to their assumption of planar parallelism when dealing with near-surface radiative transfer. Under complex terrain conditions, the scientific challenge of accurately characterizing how topographic relief affects radiation needs to be addressed.

[0005] According to the theory of mountain radiation, in areas with undulating terrain, the terrain blocks downward longwave radiation from the atmosphere and emits longwave radiation towards the adjacent surface. Since the radiation emitted by the terrain is usually greater than that emitted by the atmosphere, neglecting the effect of terrain longwave radiation in numerical weather prediction models may lead to an underestimation of downward longwave radiation from the surface. Researchers have developed an improved satellite brightness temperature simulation scheme that considers the sub-pixel terrain radiation effect based on the AGRI geostationary satellite CRTM radiative transfer model. Long-term series evaluations show that the new scheme effectively eliminates terrain-related brightness temperature simulation biases.

[0006] However, previous studies only developed forward operators for topographic radiation correction schemes, which only achieved brightness temperature simulation. For data assimilation, it is equally important to consider the shielding effect of terrain on downlink radiation and the emission effect of adjacent terrain in the observation operators. To achieve variational assimilation of satellite data for complex terrain, it is necessary to further develop tangent linear operators and adjoint operators for the forward topographic radiation operator. In addition, further incorporating topographic radiation correction into the brightness temperature Jacobian is essential to achieve practical results in brightness temperature assimilation of satellite data with complex terrain.

[0007] Considering the current problem of improving the variational assimilation accuracy of satellite brightness temperature data in complex terrain areas, it is necessary to further extend the positive operator of terrain radiation correction to its tangent linear operator and adjoint operator, so as to support the operation of variational assimilation and realize the overall scheme of observation operators for variational assimilation of satellite brightness temperature data in complex terrain. Summary of the Invention

[0008] The present invention aims to at least partially solve one of the technical problems existing in the related art.

[0009] The purpose of this invention is to provide a method for constructing a brightness temperature variational assimilation observation operator for geostationary meteorological satellites in complex terrain. This method further extends the positive operator of terrain radiation correction to its tangent linear operator and adjoint operator, thereby achieving variational assimilation of satellite data for complex terrain and improving the assimilation effect of geostationary meteorological satellite data in complex and undulating terrain areas.

[0010] To achieve the above objectives, the present invention provides a method for constructing a brightness temperature variational assimilation observation operator for geostationary meteorological satellites in complex terrain, comprising the following steps:

[0011] S1. Considering the sub-pixel topographic radiation effect, the sub-pixel topographic correction parameter is introduced into the surface radiation term of the CRTM radiative transfer model to construct a positive operator for the surface radiation term of complex terrain.

[0012] S2. Linearize the surface radiation term of complex terrain containing the sub-pixel terrain correction parameters, and establish a tangent linear operator for the surface radiation term of complex terrain.

[0013] S3. Perform the adjoint transpose of the tangent linear operator to establish the adjoint operator for the surface radiation term of complex terrain;

[0014] S4. The forward observation operator, tangent linear operator and adjoint operator are coupled to the corresponding modules of the CRTM radiative transfer model, and together they serve as the brightness temperature variational assimilation observation operator for geostationary meteorological satellites under complex terrain.

[0015] A further preferred technical solution of the present invention is that, in step S1, the sub-pixel terrain correction parameters are introduced into the surface radiation term of the CRTM radiative transfer model to construct a positive operator for the surface radiation term of complex terrain; specifically:

[0016] Using STRM topographic elevation data, sub-pixel slopes are generated within each observation pixel of the geostationary meteorological satellite AGRI. , 2nd Pixel Slope and sky visibility factor ;

[0017] Calculate the topographic radiation correction parameters at the AGRI pixel scale and They are respectively:

[0018] ;

[0019] ;

[0020] in, N represents the number of sub-pixel grid points contained within the AGRI pixel scale.

[0021] Orographic radiation correction parameters and In the surface radiation term of the CRTM radiative transfer model, the surface radiation term for complex terrain is introduced. Represented as:

[0022] ;

[0023] in, Indicates the surface emissivity; Let be the Planck function of Earth's surface temperature; Indicates surface reflectance; Indicates air pressure ,temperature Planck function at time; In the direction of satellite observation From air pressure Transmittance to the top of the atmosphere, It represents the air pressure at the Earth's surface.

[0024] Preferably, the sub-pixel slope The method for obtaining it is as follows:

[0025] First, use the terrain height data from the terrain elevation data. Horizontal coordinates and Calculate the elevation gradient of the terrain. and ;

[0026] Then the sub-pixel slope is calculated. :

[0027] .

[0028] Preferably, the sky visibility factor The three-dimensional visibility of the sky is represented by the following expression:

[0029] ;

[0030] in, It is the first Azimuth angles in each direction, For the first Maximum elevation angle in each direction; It represents a total of 24 directions, ranging from 0° to 360° in 15° increments.

[0031] Preferably, step S2 involves linearizing the complex terrain surface radiation term containing the sub-pixel terrain correction parameters to establish a tangent linear operator for the complex terrain surface radiation term; specifically:

[0032] Define atmospheric downdraft longwave radiance for ;

[0033] Then, the surface radiation term of complex terrain Represented as:

[0034] ;

[0035] Surface radiation terms for complex terrain Linearization yields the tangent linear operator for the surface radiation term, expressed as:

[0036] ;

[0037] in, , , and Let these be Planck functions representing the downflow radiation, surface emissivity, surface reflectivity, and surface temperature of the ground state, respectively. , , and Let be Planck functions representing the downward radiation, surface emissivity, surface reflectivity, and surface temperature of the disturbance dynamics, respectively.

[0038] Preferably, step S3 involves performing an adjoint transpose on the tangent linear operator to establish an adjoint operator for the surface radiation term in complex terrain; specifically:

[0039] Transpose the tangent linear operator of the surface radiation term to obtain the surface radiation term of any variable F relative to complex terrain. Partial derivatives , and the Planck function of arbitrary variable F with respect to surface temperature Downward longwave radiance of the atmosphere Surface emissivity Surface reflectivity The functional relationship of partial derivatives, specifically expressed as follows:

[0040] ;

[0041] ;

[0042] ;

[0043] ;

[0044] in, , , and These represent Planck functions of any variable F with respect to surface temperature. Downward longwave radiance of the atmosphere Surface emissivity and surface emissivity Functional relationships of partial derivatives.

[0045] Preferably, in step S4, the positive operator of the complex terrain surface radiation term obtained in step S1 is coupled to the CRTM radiative transfer model, the tangent linear operator of the complex terrain surface radiation term obtained in step S2 is coupled to the tangent linear module of the CRTM radiative transfer model, and the adjoint operator of the complex terrain surface radiation term obtained in step S3 is coupled to the adjoint module of the CRTM radiative transfer model.

[0046] Next, the gradient of the satellite brightness temperature observation penalty term is calculated, the gradient of the cost function is calculated, and the variational assimilation system for satellite brightness temperature data improved for complex terrain is constructed.

[0047] In another aspect, the present invention provides a non-transitory computer-readable storage medium storing computer instructions that cause a computer to execute the above-described method for constructing brightness temperature variational assimilation observation operators for geostationary meteorological satellites with complex terrain.

[0048] In another aspect, the present invention provides an electronic device, comprising: a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus, and the processor calls logical instructions in the memory to execute the above-mentioned method for constructing brightness temperature variational assimilation observation operators for geostationary meteorological satellites in complex terrain.

[0049] In another aspect, the present invention provides a computer program product, the computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, wherein when the computer program is executed by a processor, the computer executes the above-described method for constructing brightness temperature variational assimilation observation operators for geostationary meteorological satellites in complex terrain.

[0050] Beneficial effects: This invention reflects the effects of terrain on radiation shielding and the emission effect of adjacent terrain in the forward operator, tangent linear operator and adjoint operator, and not only in the forward operator when simulating satellite brightness temperature. It can effectively improve the variational assimilation level of infrared brightness temperature data from geostationary meteorological satellites, especially the variational assimilation level in complex and undulating terrain areas. Attached Figure Description

[0051] Figure 1 This is a flowchart of the method for constructing a brightness temperature variational assimilation observation operator for geostationary meteorological satellites in complex terrain, as described in this invention.

[0052] Figure 2 The figure shows the difference in simulation results of Jacobi (the sensitivity of brightness temperature to temperature and humidity) of the AGRI surface sensitive channel using the traditional observation operator and the new observation operator constructed in this invention.

[0053] Figure 3 The simulation difference of the brightness temperature deviation of the AGRI surface sensitive channel is shown in the figure between the traditional observation operator and the new observation operator constructed in this invention.

[0054] Figure 4 The diagram shows the relative humidity analysis field effect after assimilating satellite data using traditional observation operators and the new observation operator constructed in this invention. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, embodiments of this invention, and should not be construed as limiting the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. In the description of this invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0056] The following is combined with Figures 1-4 This invention describes a method for constructing brightness temperature variational assimilation observation operators for geostationary meteorological satellites in complex terrain.

[0057] Example 1: While existing geostationary meteorological satellite infrared data assimilation operators can consider the impact of complex terrain undulations on near-surface downflow longwave radiation during forward operator simulation, the lack of tangent linear operators and adjoint operators prevents the calculation of the gradient of the cost function for surface radiation, thus hindering its application in variational assimilation. This results in unsatisfactory assimilation of satellite infrared brightness temperature in topographic regions. Therefore, improvements are needed.

[0058] To address the aforementioned technical shortcomings, this embodiment will establish an infrared brightness temperature variational assimilation observation operator scheme adapted to complex terrain for the AGRI infrared imager of the geostationary meteorological satellite. In complex terrain areas, based on the radiative transfer positive operator that considers the satellite sub-pixel topographic radiation effect, its tangent linear operator and adjoint operator will be developed, including the development of tangent linear models and adjoint models for the sub-pixel topographic radiation correction term. This will construct a complete observation operator scheme suitable for variational assimilation. For the three-dimensional variational assimilation system of the Weather Research and Forecasting (WRF) numerical model, a new scheme for geostationary meteorological satellite brightness temperature assimilation observation operators will be established to improve the rationality and accuracy of assimilation.

[0059] like Figure 1 As shown, the specific steps include the following:

[0060] The first step is to construct a positive operator for the surface radiation term of complex terrain.

[0061] Using STRM topographic elevation data, sub-pixel slopes are generated within each observation pixel of the geostationary meteorological satellite AGRI. , 2nd Pixel Slope and sky visibility factor ;

[0062] Sub-pixel slope First, use the terrain height data from the terrain elevation data. Horizontal coordinates and Calculate the elevation gradient of the terrain. and Then, the sub-pixel slope is calculated. :

[0063] .

[0064] Sky Visible Factors The three-dimensional visibility of the sky is represented by the following expression:

[0065] ;

[0066] in, It is the first Azimuth angles in each direction, For the first Maximum elevation angle in each direction; It represents a total of 24 directions, ranging from 0° to 360° in 15° increments.

[0067] Calculate the topographic radiation correction parameters at the AGRI pixel scale and They are respectively:

[0068] ;

[0069] ;

[0070] in, N represents the number of sub-pixel grid points contained within the AGRI pixel scale.

[0071] Orographic radiation correction parameters and In the CRTM radiative transfer model, the traditional surface radiation term is expressed as:

[0072] ;

[0073] Introducing topographic radiation correction parameters and Subsequently, surface radiation items in complex terrain Represented as:

[0074] ;

[0075] in, Indicates the surface emissivity; Let be the Planck function of Earth's surface temperature; Indicates surface reflectance; Indicates air pressure ,temperature Planck function at time; In the direction of satellite observation From air pressure Transmittance to the top of the atmosphere, It represents the air pressure at the Earth's surface.

[0076] Terrain correction parameters in flat areas and Therefore, it can degenerate into a traditional scheme, compatible with applications in generally flat areas. For areas with undulating terrain, the terrain correction parameters... and The surface radiation term will be adjusted to reflect the shielding effect of topography on radiation and the radiation emission effect of adjacent topography.

[0077] The second step is to construct the tangent linear operator for the surface radiation term of complex terrain.

[0078] Define atmospheric downdraft longwave radiance for ;

[0079] Then, the surface radiation term of complex terrain Represented as:

[0080] ;

[0081] Surface radiation terms for complex terrain Linearization yields the tangent linear operator for the surface radiation term, expressed as:

[0082] ;

[0083] in, , , and Let these be Planck functions representing the downflow radiation, surface emissivity, surface reflectivity, and surface temperature of the ground state, respectively. , , and Let be Planck functions representing the downward radiation, surface emissivity, surface reflectivity, and surface temperature of the disturbance dynamics, respectively.

[0084] The invention is unique compared to traditional solutions in two ways: firstly, the developed tangent linear operator is designed for surface radiation terms in complex terrain. Instead of the planar parallel surface radiation term of the traditional scheme, this involves correction terms related to P1 and P2 during linearization. Secondly, to ensure the correctness of the developed tangent linear operator, this embodiment performs a tangent linearity correctness check, the specific steps of which are as follows:

[0085] For the surface radiation term, Defined as exist along The derivative of the direction, for the state variable and disturbance quantity ,calculate (Right now The input is ), (Right now The input is )and (Right now The input is ).definition ,Will Values ​​range from 10 -1 Gradually reduce the magnitude to 10 -8 ,along with The magnitude decreased. It should get smaller and smaller, among which It is the L2 norm, calculated by the developed model. The ratio is close to 1, indicating that the development is correct. This method verifies the correctness of the development of the tangent linear operator.

[0086] The third step is to construct the adjoint operator for the surface radiation term of complex terrain.

[0087] Transpose the tangent linear operator of the surface radiation term to obtain the surface radiation term of any variable F relative to complex terrain. Partial derivatives , and the Planck function of arbitrary variable F with respect to surface temperature Downward longwave radiance of the atmosphere Surface emissivity Surface reflectivity The functional relationship of partial derivatives, specifically expressed as follows:

[0088] ;

[0089] ;

[0090] ;

[0091] ;

[0092] in, , , and These represent Planck functions of any variable F with respect to surface temperature. Downward longwave radiance of the atmosphere Surface emissivity and surface emissivity Functional relationships of partial derivatives.

[0093] The invention is unique compared to traditional solutions in two ways: first, the developed adjoint operator is designed for surface radiation terms in complex terrain. Instead of the planar parallel surface radiation term of the traditional scheme, the adjoint transpose involves correction terms related to P1 and P2. Secondly, to ensure the correctness of the developed adjoint operator, an adjoint correctness check was performed, the specific steps of which are as follows:

[0094] For any mode space perturbation and observation space disturbance Accompanying operator Must strictly meet ,in Represents the inner product. Definition When the operator is developed correctly It should be close to 0, calculated by the developed model. This verifies the correctness of the development of the adjoint operator.

[0095] The fourth step is to establish an overall improvement scheme for the satellite brightness-temperature assimilation observation operator of variational assimilation.

[0096] The forward operator of the complex terrain surface radiation term is coupled to the CRTM radiative transfer model, the tangent linear operator of the complex terrain surface radiation term is coupled to the tangent linear module of the CRTM radiative transfer model, and the adjoint operator of the complex terrain surface radiation term is coupled to the adjoint module of the CRTM radiative transfer model.

[0097] Next, the gradient of the satellite brightness temperature observation penalty term is calculated, the gradient of the cost function is calculated, and the variational assimilation system for satellite brightness temperature data improved for complex terrain is constructed.

[0098] Figure 2 The simulation differences between the traditional observation operator and the new observation operator constructed in this invention for the Jacobian (brightness temperature sensitivity relative to temperature and humidity) of the AGRI surface sensitive channel are presented. In topographically undulating regions, the new observation operator scheme exhibits higher brightness temperature sensitivity relative to surface temperature, lower brightness temperature sensitivity relative to atmospheric temperature, and higher brightness temperature sensitivity relative to atmospheric humidity.

[0099] Figure 3 The simulation differences between the traditional observation operator and the new observation operator for the brightness temperature deviation of AGRI surface sensitive channel 13 (wavelength: 12.0 µm) are presented. In areas with undulating terrain, the brightness temperature simulation deviation of the traditional observation operator gradually increases as the sky visibility factor decreases (i.e., the terrain complexity increases), indicating a reduced ability to simulate complex terrain. In contrast, the brightness temperature simulation deviation of the new observation operator does not change significantly, indicating a better ability to simulate complex terrain.

[0100] Figure 4The results of relative humidity analysis after assimilating satellite data using traditional and new observation operators are presented. The gray boxes represent areas with undulating terrain. It can be seen that the relative humidity error in the background field of the numerical model is relatively large (dots in the figure). After assimilation using the traditional observation operator scheme, there is no significant adjustment to the relative humidity. However, after assimilation using the new observation operator, the relative humidity is adjusted in the direction of reducing the error, indicating that the new observation operator has higher assimilation accuracy in areas with undulating terrain.

[0101] Example 2: This example provides a non-transitory computer-readable storage medium storing computer instructions that enable a computer to execute a method for constructing a brightness-temperature variational assimilation observation operator for geostationary meteorological satellites with complex terrain. This method includes the following steps:

[0102] S1. Considering the sub-pixel topographic radiation effect, the sub-pixel topographic correction parameter is introduced into the surface radiation term of the CRTM radiative transfer model to construct a positive operator for the surface radiation term of complex terrain.

[0103] S2. Linearize the complex terrain surface radiation term containing the sub-pixel terrain correction parameters, and establish the tangent linear operator for the complex terrain surface radiation term;

[0104] S3. Perform the adjoint transpose of the tangent linear operator to establish the adjoint operator of the complex terrain surface radiation term;

[0105] S4. The forward observation operator, tangent linear operator and adjoint operator are coupled to the corresponding modules of the CRTM radiative transfer model, and together they serve as the brightness temperature variational assimilation observation operator for geostationary meteorological satellites under complex terrain.

[0106] Example 3: This example provides an electronic device that may include a processor, a communication interface, a memory, and a communication bus. The processor, communication interface, and memory communicate with each other via the communication bus. The processor can call logical instructions from the memory to execute a method for constructing a brightness-temperature variational assimilation observation operator for geostationary meteorological satellites in complex terrain. This method includes the following steps:

[0107] S1. Considering the sub-pixel topographic radiation effect, the sub-pixel topographic correction parameter is introduced into the surface radiation term of the CRTM radiative transfer model to construct a positive operator for the surface radiation term of complex terrain.

[0108] S2. Linearize the complex terrain surface radiation term containing the sub-pixel terrain correction parameters, and establish the tangent linear operator for the complex terrain surface radiation term;

[0109] S3. Perform the adjoint transpose of the tangent linear operator to establish the adjoint operator of the complex terrain surface radiation term;

[0110] S4. The forward observation operator, tangent linear operator and adjoint operator are coupled to the corresponding modules of the CRTM radiative transfer model, and together they serve as the brightness temperature variational assimilation observation operator for geostationary meteorological satellites under complex terrain.

[0111] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, and can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0112] Example 4: This example provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute a method for constructing a brightness-temperature variational assimilation observation operator for geostationary meteorological satellites in complex terrain. This method includes the following steps:

[0113] S1. Considering the sub-pixel topographic radiation effect, the sub-pixel topographic correction parameter is introduced into the surface radiation term of the CRTM radiative transfer model to construct a positive operator for the surface radiation term of complex terrain.

[0114] S2. Linearize the complex terrain surface radiation term containing the sub-pixel terrain correction parameters, and establish the tangent linear operator for the complex terrain surface radiation term;

[0115] S3. Perform the adjoint transpose of the tangent linear operator to establish the adjoint operator of the complex terrain surface radiation term;

[0116] S4. The forward observation operator, tangent linear operator and adjoint operator are coupled to the corresponding modules of the CRTM radiative transfer model, and together they serve as the brightness temperature variational assimilation observation operator for geostationary meteorological satellites under complex terrain.

[0117] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0118] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for constructing a brightness temperature variational assimilation observation operator for geostationary meteorological satellites in complex terrain, characterized in that, Includes the following steps: S1. Considering the sub-pixel topographic radiation effect, the sub-pixel topographic correction parameters are introduced into the surface radiation term of the CRTM radiative transfer model to construct a positive operator for the surface radiation term of complex terrain; specifically: Using STRM topographic elevation data, sub-pixel slopes are generated within each observation pixel of the geostationary meteorological satellite AGRI. , 2nd Pixel Slope and sky visibility factor ; Calculate the topographic radiation correction parameters at the AGRI pixel scale and They are respectively: ； ； in, N represents the number of sub-pixel grid points contained within the AGRI pixel scale. Orographic radiation correction parameters and In the surface radiation term of the CRTM radiative transfer model, the surface radiation term for complex terrain is introduced. Represented as: ； in, Indicates the surface emissivity; Let be the Planck function of Earth's surface temperature; Indicates surface reflectance; Indicates air pressure ,temperature Planck function at time; In the direction of satellite observation From air pressure Transmittance to the top of the atmosphere, Indicates surface air pressure; S2. Linearize the surface radiation term of complex terrain containing the sub-pixel terrain correction parameters, and establish a tangent linear operator for the surface radiation term of complex terrain; specifically: Define atmospheric downdraft longwave radiance for ; Then, the surface radiation term of complex terrain Represented as: ； Surface radiation terms for complex terrain Linearization yields the tangent linear operator for the surface radiation term, expressed as: ； in, , , and Let these be Planck functions representing the downflow radiation, surface emissivity, surface reflectivity, and surface temperature of the ground state, respectively. , , and , respectively, represent the Planck functions of the perturbation dynamics: downflow radiation, surface emissivity, surface reflectivity, and surface temperature; S3. Perform the adjoint transpose of the tangent linear operator to establish the adjoint operator for the surface radiation term of complex terrain; specifically: Transpose the tangent linear operator of the surface radiation term to obtain the surface radiation term of any variable F relative to complex terrain. Partial derivatives , and the Planck function of arbitrary variable F with respect to surface temperature Downward longwave radiance of the atmosphere Surface emissivity Surface reflectivity The functional relationship of partial derivatives, specifically expressed as follows: ； ； ； ； in, , , and These represent Planck functions of any variable F with respect to surface temperature. Downward longwave radiance of the atmosphere Surface emissivity and surface reflectivity The functional relationship of partial derivatives; S4. The forward observation operator, tangent linear operator and adjoint operator are coupled to the corresponding modules of the CRTM radiative transfer model, and together they serve as the brightness temperature variational assimilation observation operator for geostationary meteorological satellites under complex terrain.

2. The method for constructing a brightness temperature variational assimilation observation operator for geostationary meteorological satellites in complex terrain according to claim 1, characterized in that, The sub-pixel slope The method for obtaining it is as follows: First, use the terrain height data from the terrain elevation data. Horizontal coordinates and Calculate the elevation gradient of the terrain. and ; Then the sub-pixel slope is calculated. : 。 3. The method for constructing a brightness temperature variational assimilation observation operator for geostationary meteorological satellites in complex terrain according to claim 2, characterized in that, The Sky Visibility Factor The three-dimensional visibility of the sky is represented by the following expression: ； in, It is the first Azimuth angles in each direction, For the first Maximum elevation angle in each direction; It represents a total of 24 directions, ranging from 0° to 360° in 15° increments.

4. The method for constructing a brightness temperature variational assimilation observation operator for geostationary meteorological satellites in complex terrain according to claim 1, characterized in that, In step S4, the forward operator of the complex terrain surface radiation term obtained in step S1 is coupled to the CRTM radiative transfer model, the tangent linear operator of the complex terrain surface radiation term obtained in step S2 is coupled to the tangent linear module of the CRTM radiative transfer model, and the adjoint operator of the complex terrain surface radiation term obtained in step S3 is coupled to the adjoint module of the CRTM radiative transfer model. Next, the gradient of the satellite brightness temperature observation penalty term is calculated, the gradient of the cost function is calculated, and the variational assimilation system for satellite brightness temperature data improved for complex terrain is constructed.

5. A non-transitory computer-readable storage medium, characterized in that, It stores computer instructions that enable the computer to execute the method for constructing brightness temperature variational assimilation observation operators for complex terrain geostationary meteorological satellites as described in any one of claims 1-4.

6. An electronic device, characterized in that, include: The system includes a processor, a communication interface, a memory, and a communication bus. The processor, communication interface, and memory communicate with each other via the communication bus. The processor calls logical instructions from the memory to execute the method for constructing brightness temperature variational assimilation observation operators for complex terrain geostationary meteorological satellites as described in any one of claims 1-4.

7. A computer program product, characterized in that, The computer program product includes a computer program stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer executes the method for constructing brightness temperature variational assimilation observation operators for complex terrain geostationary meteorological satellites as described in any one of claims 1-4.

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