Method and system for calculating the effective brightness temperature of the moon based on brightness temperature observation by satellite-borne microwave radiometer

Abstract

The present invention discloses a method and system for calculating the effective brightness temperature of the moon based on the brightness temperature observed by a satellite-borne microwave radiometer. The method comprises the following steps: calculating the functional relationship between the brightness temperature of the moon model and the moon latitude and the moon phase; matching the moon coordinate system with the satellite-borne microwave radiometer antenna coordinate system; determining the azimuth range of the moon on the antenna pattern according to the angle occupied by the moon in the antenna field of view, and calculating the antenna efficiency weight of the selected position; calculating the correction coefficient of the brightness temperature of the moon according to the simulated effective brightness temperature of the moon obtained by the microwave radiometer, the observed brightness temperature of the microwave radiometer obtained by the simulated method, and the antenna efficiency weight; calculating the cosmic background observed brightness temperature of the selected position; obtaining the observed brightness temperature of the microwave radiometer at the selected position, and calculating the effective brightness temperature of the moon based on the cosmic background observed brightness temperature, the moon brightness temperature correction coefficient and the antenna efficiency weight. The present invention combines the actual observation data of the satellite-borne microwave radiometer and the result of simulating the moon entering the antenna to obtain an accurate effective brightness temperature of the moon.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave remote sensing effective brightness temperature of the moon, and in particular to a method and system for calculating the effective brightness temperature of the moon based on brightness temperature observation by a satellite-borne microwave radiometer. Background Art

[0002] A microwave radiometer is a passive microwave remote sensing system consisting of an antenna and a receiving system. It obtains the physical characteristics of a target by receiving the target's microwave self-radiation. The satellite-borne microwave radiometer adopts a two-point calibration scheme, which establishes the corresponding relationship between the output voltage and the brightness temperature by measuring the voltage of two reference calibration sources with known temperatures, the black body carried on the satellite and the cold space cosmic radiation. When the microwave radiometer antenna rotates to the cold space area to calibrate the cold space radiation, the moon may enter the antenna's observation field of view, and the lunar radiation at this time is captured by the satellite-borne microwave radiometer.

[0003] As the only natural satellite of the Earth and one of the important celestial bodies in the solar system, the lunar surface records the earliest stages of the formation of the Earth and the solar system, and also records a series of important planetary processes that have occurred, such as impact craters, volcanic activity, and space weathering, which are directly related to similar processes observed on other celestial bodies in the solar system. The lunar surface temperature, as an important input to the lunar exosphere, can regulate the speed of exosphere particles and the adsorption of particles. Therefore, constructing a lunar brightness temperature model is of great scientific significance.

[0004] The lunar observation brightness temperature can be obtained by using the radiation signal of the moon entering the cold field of view of the satellite-borne microwave radiometer, and the lunar radiation brightness temperature can be further modeled. The exploration of the lunar radiation brightness temperature can increase human scientific understanding of lunar evolution; at the same time, since the lunar microwave radiation is relatively stable, it is hoped that the moon can be used as a reference calibration on the satellite, providing a stable radiation source for the on-orbit calibration of the microwave radiometer, thereby achieving the purpose of improving the calibration accuracy of the satellite-borne microwave radiometer.

[0005] Existing methods for calculating lunar brightness temperature either directly use observational data to calculate and analyze the microwave brightness temperature on the lunar surface using a theoretical lunar temperature stratification brightness temperature model, or obtain the lunar surface brightness temperature through a theoretical radiation transmission model without the support of actual observational data, or directly draw a brightness temperature distribution map through data from close-range observations of the moon, which is not very accurate. Summary of the invention

[0006] In order to overcome the defects and shortcomings of the prior art, the present invention provides a method and system for calculating the effective brightness temperature of the moon based on the brightness temperature observed by a satellite-borne microwave radiometer. The present invention aims at the situation where the moon enters the observation field of view of the satellite-borne microwave radiometer antenna, and uses the observed brightness temperature of the satellite-borne microwave radiometer to calculate the effective brightness temperature of the moon. The brightness temperature correction coefficient of the moon is calculated by simulating the moon entering the antenna field of view to obtain the accurate effective brightness temperature of the moon.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for calculating the effective brightness temperature of the moon based on brightness temperature observed by a satellite-borne microwave radiometer, comprising the following steps:

[0009] Calculate the function relationship between the brightness temperature of the lunar model and the lunar latitude and lunar phase;

[0010] Match the lunar coordinate system with the satellite-borne microwave radiometer antenna coordinate system;

[0011] Obtain the angle between the center of the moon and the center of the field of view of the microwave radiometer antenna at the selected location, as well as the azimuth of the moon entering the antenna to determine the position of the moon in the field of view of the antenna, and determine the azimuth range of the moon on the antenna radiation pattern based on the angle occupied by the moon in the field of view of the antenna, and calculate the antenna efficiency weight at the selected location;

[0012] The effective brightness temperature of the moon of the microwave radiometer at the selected location is simulated according to the position and phase of the moon, the observed brightness temperature of the microwave radiometer at the selected location is simulated, and the correction coefficient of the moon brightness temperature is calculated according to the simulated effective brightness temperature of the moon of the microwave radiometer, the simulated observed brightness temperature of the microwave radiometer and the antenna efficiency weight;

[0013] Calculate the observed brightness temperature of the cosmic background at the selected location;

[0014] The observed brightness temperature of the microwave radiometer at the selected location is obtained, and the effective brightness temperature of the moon is calculated based on the observed brightness temperature of the cosmic background, the lunar brightness temperature correction factor and the antenna efficiency weight.

[0015] As a preferred technical solution, the functional relationship between the brightness temperature of the lunar model and the lunar latitude and lunar phase is calculated, which specifically includes:

[0016] The brightness temperature of the lunar sun side directly exposed to solar radiation is expressed as:

[0017] T moon_model_ss (ω)=[S(1-A)cos(ω) / εσ] 1 / 4

[0018] Among them, ω is the lunar latitude, S is the solar constant, A is the albedo, ε is the emissivity, σ is the Boltzmann constant, and the longitude range of the solar side is -90° to 90°;

[0019] The brightness temperature of the dark side of the moon that is not directly irradiated by the sun is expressed as:

[0020]

[0021] Among them, δ is the longitude of the moon, a i is a constant;

[0022] When the moon phase is The range of lunar longitude observed by the radiometer is

[0023] As a preferred technical solution, the lunar coordinate system and the satellite-borne microwave radiometer antenna coordinate system are matched, specifically including:

[0024] The lunar disk is divided into a grid, and the position of the moon on the antenna pattern is determined based on the angle between the center of the moon and the center of the field of view of the microwave radiometer antenna. The lunar coordinates are matched to the coordinates on the antenna pattern, and the azimuth angle of each lunar disk grid on the antenna pattern is determined to complete the spatial matching of the coordinate systems of the moon and the satellite-borne microwave radiometer antenna.

[0025] As a preferred technical solution, the antenna efficiency weight at the selected location is calculated, which is specifically expressed as:

[0026]

[0027] Where p represents the antenna pattern, represents the antenna azimuth, and Ω is the solid angle of the microwave radiometer antenna pattern occupied by the moon.

[0028] As a preferred technical solution, the effective brightness temperature of the moon of the microwave radiometer at the selected location is simulated according to the position and phase of the moon, and the observed brightness temperature of the microwave radiometer at the selected location is simulated, which is specifically expressed as:

[0029]

[0030]

[0031] in, represents the lunar effective brightness temperature obtained by simulating microwave radiometer, TB moon_model represents the observed brightness temperature of the microwave radiometer obtained by simulation, T moon_model represents the lunar brightness temperature model, p represents the antenna pattern, represents the antenna azimuth, and Ω is the solid angle of the microwave radiometer antenna pattern occupied by the moon.

[0032] As a preferred technical solution, the lunar brightness temperature correction coefficient is calculated based on the simulated lunar effective brightness temperature of the microwave radiometer, the simulated observed brightness temperature of the microwave radiometer and the antenna efficiency weight, which is specifically expressed as:

[0033]

[0034] Where α is the correction coefficient of the lunar brightness temperature, represents the lunar effective brightness temperature obtained by simulating microwave radiometer, TB moon_modelrepresents the observed brightness temperature of the microwave radiometer obtained by simulation, Represents the antenna efficiency weight.

[0035] As a preferred technical solution, the cosmic background observation brightness temperature at the selected location is calculated, which is specifically expressed as:

[0036]

[0037] Among them, TB cos represents the brightness temperature of the cosmic background radiation, p represents the antenna pattern, represents the antenna azimuth, and Ω is the solid angle of the microwave radiometer antenna pattern occupied by the moon.

[0038] As a preferred technical solution, the observed brightness temperature of the microwave radiometer at the selected location is obtained, which is specifically expressed as:

[0039]

[0040] Among them, T moon is the brightness temperature of the moon, p represents the antenna pattern, represents the antenna azimuth, Ω is the solid angle of the microwave radiometer antenna pattern occupied by the moon, and TB cos Represents the brightness temperature of the cosmic background radiation.

[0041] As a preferred technical solution, the observed brightness temperature of the microwave radiometer at the selected location is obtained, and the effective brightness temperature of the moon is calculated based on the observed brightness temperature of the cosmic background, the brightness temperature correction coefficient of the moon and the antenna efficiency weight, which specifically includes:

[0042]

[0043] Among them, TB obs represents the observed brightness temperature of the microwave radiometer, TB cos_obs is the observed brightness temperature of the cosmic background, α is the correction coefficient of the brightness temperature of the moon, Represents the antenna efficiency weight coefficient.

[0044] The present invention also provides a system for calculating the effective brightness temperature of the moon based on the brightness temperature observed by a satellite-borne microwave radiometer, which is used to implement the above-mentioned method for calculating the effective brightness temperature of the moon based on the brightness temperature observed by a satellite-borne microwave radiometer. The system comprises: a moon model brightness temperature calculation module, a coordinate matching module, an antenna efficiency weight calculation module, a moon brightness temperature correction coefficient calculation module, a cosmic background observation brightness temperature calculation module, and a moon effective brightness temperature calculation module;

[0045] The lunar model brightness temperature calculation module is used to calculate the functional relationship between the lunar model brightness temperature and the lunar latitude and lunar phase;

[0046] The coordinate matching module is used to match the lunar coordinate system with the satellite-borne microwave radiometer antenna coordinate system;

[0047] The antenna efficiency weight calculation module is used to obtain the angle between the center of the moon at the selected position and the center of the field of view of the microwave radiometer antenna, as well as the azimuth of the moon entering the antenna to determine the position of the moon in the field of view of the antenna, and determine the azimuth range of the moon on the antenna radiation pattern according to the angle occupied by the moon in the field of view of the antenna, and calculate the antenna efficiency weight of the selected position;

[0048] The lunar brightness temperature correction coefficient calculation module is used to simulate the lunar effective brightness temperature of the microwave radiometer at the selected position according to the lunar position and lunar phase, simulate the observed brightness temperature of the microwave radiometer at the selected position, and calculate the lunar brightness temperature correction coefficient according to the simulated lunar effective brightness temperature of the microwave radiometer, the simulated observed brightness temperature of the microwave radiometer and the antenna efficiency weight;

[0049] The cosmic background observation brightness temperature calculation module is used to calculate the cosmic background observation brightness temperature of the selected position;

[0050] The lunar effective brightness temperature calculation module is used to obtain the observed brightness temperature of the microwave radiometer at the selected position, and calculate the lunar effective brightness temperature based on the cosmic background observed brightness temperature, the lunar brightness temperature correction coefficient and the antenna efficiency weight.

[0051] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0052] Aiming at the situation that the moon enters the observation field of view of the antenna of a space-borne microwave radiometer, the present invention uses the observed brightness temperature of the space-borne microwave radiometer to calculate the effective brightness temperature of the moon, simulates the moon entering the antenna field of view to calculate the brightness temperature correction coefficient of the moon, and combines the actual observation data of the space-borne microwave radiometer and the scheme of simulating the moon entering the antenna result to obtain the accurate effective brightness temperature of the moon. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a flow chart of a method for calculating the effective brightness temperature of the moon based on brightness temperature observed by a satellite-borne microwave radiometer according to the present invention;

[0054] Figure 2 This is a schematic diagram of the moon entering the antenna field of view;

[0055] Figure 3 Schematic diagram of the moon's movement over the antenna pattern. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0057] Example 1

[0058] like Figure 1 As shown, this embodiment provides a method for calculating the effective brightness temperature of the moon based on brightness temperature observed by a satellite-borne microwave radiometer, comprising the following steps:

[0059] like Figure 2 As shown in the figure, when the moon enters the antenna field of view, the observed brightness temperature of the microwave radiometer is the convolution of the antenna pattern of the microwave radiometer and the brightness temperature within the antenna field of view, which is the joint contribution of the brightness temperature of the cosmic background radiation and the brightness temperature of the moon. The 3dB BW in the figure represents the half-power beam width of the microwave radiometer antenna; the observed brightness temperature of the microwave radiometer is expressed as:

[0060]

[0061] Among them, TB obs is the observed brightness temperature of the microwave radiometer, T moon is the lunar brightness temperature, TB cos =2.73K is the brightness temperature of the cosmic background radiation, p represents the antenna pattern, represents the antenna azimuth, Ω is the solid angle of the microwave radiometer antenna pattern occupied by the moon;

[0062] Defining TB moon_obs Observe the brightness temperature of the moon, TB cos_obs The brightness temperature of the cosmic background observations, is the effective brightness temperature of the moon, respectively expressed as:

[0063]

[0064]

[0065]

[0066] definition is the antenna efficiency weight coefficient, expressed as:

[0067]

[0068] Introducing the lunar brightness temperature correction coefficient α, equation (2) can be expressed as:

[0069]

[0070] The effective brightness temperature of the moon is:

[0071]

[0072] This embodiment calculates the effective brightness temperature of the moon based on the brightness temperature observed by the satellite-borne microwave radiometer The method is shown in formula (7), which specifically includes the following steps:

[0073] Step 1: Calculate the function relationship between the brightness temperature of the lunar model and the lunar latitude and lunar phase;

[0074] The brightness temperature of the lunar model is related to the lunar latitude and longitude. The hemisphere of the lunar surface that is directly exposed to solar radiation is called the lunar sun side, and its brightness temperature can be expressed as:

[0075] T moon_model_ss (ω)=[S(1-A)cos(ω) / εσ] 1 / 4 (8)

[0076] Among them, ω is the lunar latitude (ranging from -90° to 90°), S is the solar constant, A is the albedo, ε is the emissivity, σ is the Boltzmann constant, and the longitude range of the solar side is -90° to 90°.

[0077] The hemisphere that is not directly irradiated by the sun is the dark side of the moon, and its brightness temperature can be expressed as:

[0078] T moon_model_ns (ω, δ) = ∑ i＝0，…，5 (a i δ i )+35(sin(ω)-1) (9)

[0079] Among them, δ is the longitude of the moon (range is 90°~270°), a i is a constant, a=[444.738, -448.937, 239.668, -63.8844, 8.34064, -0.423502].

[0080] When the moon phase is θ, the lunar longitude range observed by the radiometer is θ-90°~θ+90°.

[0081] Step 2: Match the lunar coordinate system with the satellite-borne microwave radiometer antenna coordinate system;

[0082] The lunar disk is divided into 1°×1° grids. The position of the moon on the antenna pattern is determined based on the angle between the center of the moon and the center of the field of view of the microwave radiometer antenna (hereinafter referred to as the angle), the lunar coordinates are matched to the coordinates on the antenna pattern, and the azimuth corresponding to each 1°×1° lunar disk grid on the antenna pattern is determined. Complete the spatial matching of the lunar and satellite-borne microwave radiometer antenna coordinate systems, and the lunar brightness temperature model can be used to calculate the antenna azimuth angle. Expressed as

[0083] Step 3: Calculate the antenna efficiency weight;

[0084] Based on the microwave radiometer antenna pattern and lunar model brightness temperature obtained from ground measurements before the satellite launch, Figure 3As shown, the scenario of the moon entering the antenna field of view is simulated (from L1, L2 to L3);

[0085] The position of the moon in the antenna field of view is determined by using the angle between the center of the moon at the L1 position and the center of the field of view of the microwave radiometer antenna, as well as the azimuth angle of the moon entering the antenna. The azimuth angle range of the moon on the antenna radiation pattern is determined based on the angle occupied by the moon in the antenna field of view. (The corresponding solid angle is Ω L1 ), calculate the antenna efficiency weight at the L1 position:

[0086]

[0087] Similarly, the antenna efficiency weights can be calculated by substituting the above formulas at the L1, L2 and L3 positions, namely:

[0088]

[0089]

[0090]

[0091] Step 4: Calculate the lunar brightness temperature correction coefficient α;

[0092] The lunar brightness temperature correction coefficient α is related to the position of the moon in the antenna and the lunar phase. Figure 3 When the L1 position in the image is used, the effective brightness temperature of the moon can be simulated according to the position and phase of the moon:

[0093]

[0094] And the observed brightness temperature of the microwave radiometer is simulated:

[0095]

[0096] Using formula (6), we can get the correction coefficient α of the lunar brightness temperature at the L1 position: L1 :

[0097]

[0098] Similarly, the lunar brightness temperature correction coefficients can be calculated at the L1, L2 and L3 positions respectively.

[0099] Step 5: Calculate the cosmic background observation brightness temperature TB cos_obs ;

[0100] The brightness temperature of the cosmic microwave background radiation is 2.73 K. For the L1 position, the brightness temperature of the cosmic background observation is TB cos_obs It can be expressed as:

[0101]

[0102] Similarly, the observed brightness temperature of the cosmic background radiation can be calculated for the L1, L2 and L3 positions.

[0103] Step 6: Calculate the effective brightness temperature of the moon;

[0104] For the L1 position, according to the observed brightness temperature TB of the microwave radiometer obs , cosmic background observation brightness temperature TB cos_obs , the lunar brightness temperature correction coefficient and the antenna efficiency weight are used to calculate the lunar effective brightness temperature, and then substituted into equation (7) to obtain:

[0105]

[0106] The effective brightness temperature of the moon can be obtained by solving

[0107] Similarly, the effective brightness temperature of the moon can be calculated for the positions L1, L2 and L3. Of course, this embodiment only uses the three positions L1, L2 and L3 as examples to solve the effective brightness temperature of the moon at different positions. In actual calculation, the effective brightness temperature of the moon at more positions can be calculated for analysis.

[0108] The present invention aims at the lunar observation brightness temperature of the microwave payload antenna's own characteristics, and calculates the lunar effective brightness temperature based on it. Specifically, according to the situation that the moon enters the observation field of view of the antenna of the spaceborne microwave radiometer, the moon brightness temperature correction coefficient is obtained by simulating the moon entering the antenna field of view, the lunar observation brightness temperature obtained by the calibration scheme of the spaceborne microwave radiometer is corrected, and the lunar effective brightness temperature is calculated.

[0109] Example 2

[0110] This embodiment provides a system for calculating the effective brightness temperature of the moon based on the brightness temperature observed by a satellite-borne microwave radiometer, which is used to implement the method of calculating the effective brightness temperature of the moon based on the brightness temperature observed by a satellite-borne microwave radiometer in the above-mentioned embodiment 1. The system includes: a lunar model brightness temperature calculation module, a coordinate matching module, an antenna efficiency weight calculation module, a lunar brightness temperature correction coefficient calculation module, a cosmic background observation brightness temperature calculation module, and a lunar effective brightness temperature calculation module;

[0111] In this embodiment, the lunar model brightness temperature calculation module is used to calculate the functional relationship between the lunar model brightness temperature and the lunar latitude and lunar phase;

[0112] In this embodiment, the coordinate matching module is used to match the lunar coordinate system with the satellite-borne microwave radiometer antenna coordinate system;

[0113] In this embodiment, the antenna efficiency weight calculation module is used to obtain the angle between the center of the moon at the selected position and the center of the field of view of the microwave radiometer antenna, and the azimuth angle of the moon entering the antenna to determine the position of the moon in the field of view of the antenna, and determine the azimuth angle range of the moon on the antenna radiation pattern according to the angle occupied by the moon in the field of view of the antenna, and calculate the antenna efficiency weight of the selected position;

[0114] In this embodiment, the lunar brightness temperature correction coefficient calculation module is used to simulate the lunar effective brightness temperature of the microwave radiometer at the selected position according to the lunar position and lunar phase, simulate the observed brightness temperature of the microwave radiometer at the selected position, and calculate the lunar brightness temperature correction coefficient according to the simulated lunar effective brightness temperature of the microwave radiometer, the simulated observed brightness temperature of the microwave radiometer and the antenna efficiency weight;

[0115] In this embodiment, the cosmic background observation brightness temperature calculation module is used to calculate the cosmic background observation brightness temperature of the selected position;

[0116] In this embodiment, the lunar effective brightness temperature calculation module is used to obtain the observed brightness temperature of the microwave radiometer at the selected location, and calculate the lunar effective brightness temperature based on the cosmic background observed brightness temperature, the lunar brightness temperature correction coefficient and the antenna efficiency weight.

[0117] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for calculating the effective brightness temperature of the moon based on brightness temperature observation by a spaceborne microwave radiometer, characterized in that: The steps include: Calculate the lunar model brightness temperature as a function of lunar latitude and lunar phase; Match the lunar coordinate system with the satellite-borne microwave radiometer antenna coordinate system; Obtain the angle between the center of the moon and the center of the field of view of the microwave radiometer antenna at the selected location, as well as the azimuth of the moon entering the antenna to determine the position of the moon in the field of view of the antenna, and determine the azimuth range of the moon on the antenna radiation pattern based on the angle occupied by the moon in the field of view of the antenna, and calculate the antenna efficiency weight at the selected location; The effective brightness temperature of the moon of the microwave radiometer at the selected location is simulated according to the position and phase of the moon, the observed brightness temperature of the microwave radiometer at the selected location is simulated, and the correction coefficient of the moon brightness temperature is calculated according to the simulated effective brightness temperature of the moon of the microwave radiometer, the simulated observed brightness temperature of the microwave radiometer and the antenna efficiency weight; Calculate the observed brightness temperature of the cosmic background at the selected location; The observed brightness temperature of the microwave radiometer at the selected location is obtained, and the effective brightness temperature of the moon is calculated based on the observed brightness temperature of the cosmic background, the lunar brightness temperature correction factor and the antenna efficiency weight.

2. The method for calculating the effective brightness temperature of the moon based on brightness temperature observation by a spaceborne microwave radiometer according to claim 1, characterized in that: Calculate the function relationship between the brightness temperature of the lunar model and the lunar latitude and lunar phase, including: The brightness temperature of the lunar sun side directly exposed to solar radiation is expressed as: T moon_model_ss (ω)=[S(1-A)cos(ω) / εσ] 1 / 4 Among them, ω is the lunar latitude, S is the solar constant, A is the albedo, ε is the emissivity, σ is the Boltzmann constant, and the longitude range of the solar side is -90° to 90°; The brightness temperature of the dark side of the moon that is not directly irradiated by the sun is expressed as: Among them, δ is the longitude of the moon, a i is a constant; When the moon phase is θ, the lunar longitude range observed by the radiometer is θ-90°~θ+90°.

3. The method for calculating the effective brightness temperature of the moon based on brightness temperature observation by a satellite-borne microwave radiometer according to claim 1, characterized in that: Match the lunar coordinate system with the satellite-borne microwave radiometer antenna coordinate system, including: The lunar disk is divided into a grid, and the position of the moon on the antenna pattern is determined based on the angle between the center of the moon and the center of the field of view of the microwave radiometer antenna. The lunar coordinates are matched to the coordinates on the antenna pattern, and the azimuth angle of each lunar disk grid on the antenna pattern is determined to complete the spatial matching of the coordinate systems of the moon and the satellite-borne microwave radiometer antenna.

4. The method for calculating the effective brightness temperature of the moon based on brightness temperature observation by a spaceborne microwave radiometer according to claim 1, characterized in that: Calculate the antenna efficiency weight at the selected location, which is specifically expressed as: Where p represents the antenna pattern, represents the antenna azimuth, and Ω is the solid angle of the microwave radiometer antenna pattern occupied by the moon.

5. The method for calculating the effective brightness temperature of the moon based on brightness temperature observation by a spaceborne microwave radiometer according to claim 1, characterized in that: The effective brightness temperature of the moon at the selected location is simulated according to the position and phase of the moon, and the observed brightness temperature of the microwave radiometer at the selected location is simulated, which is specifically expressed as: in, represents the lunar effective brightness temperature obtained by simulating microwave radiometer, TB moon_model represents the observed brightness temperature of the microwave radiometer obtained by simulation, T moon_model represents the lunar brightness temperature model, p represents the antenna pattern, represents the antenna azimuth, and Ω is the solid angle of the microwave radiometer antenna pattern occupied by the moon.

6. The method for calculating the effective brightness temperature of the moon based on brightness temperature observation by a spaceborne microwave radiometer according to claim 1 or 5, characterized in that: The lunar brightness temperature correction coefficient is calculated based on the simulated effective brightness temperature of the microwave radiometer, the simulated observed brightness temperature of the microwave radiometer and the antenna efficiency weight. The specific expression is: Where α is the correction coefficient of the lunar brightness temperature, represents the lunar effective brightness temperature obtained by simulating microwave radiometer, TB moon_model represents the observed brightness temperature of the microwave radiometer obtained by simulation, Represents the antenna efficiency weight.

7. The method for calculating the effective brightness temperature of the moon based on brightness temperature observation by a spaceborne microwave radiometer according to claim 1, characterized in that: Calculate the cosmic background observation brightness temperature at the selected location, specifically expressed as: Among them, TB cos represents the brightness temperature of the cosmic background radiation, p represents the antenna pattern, represents the antenna azimuth, and Ω is the solid angle of the microwave radiometer antenna pattern occupied by the moon.

8. The method for calculating the effective brightness temperature of the moon based on brightness temperature observation by a spaceborne microwave radiometer according to claim 1, characterized in that: Get the observed brightness temperature of the microwave radiometer at the selected location, specifically expressed as: Among them, T moon is the brightness temperature of the moon, p represents the antenna pattern, represents the antenna azimuth, Ω is the solid angle of the microwave radiometer antenna pattern occupied by the moon, and TB cos Represents the brightness temperature of the cosmic background radiation.

9. The method for calculating the effective brightness temperature of the moon based on brightness temperature observation by a spaceborne microwave radiometer according to claim 1 or 8, characterized in that: Obtain the observed brightness temperature of the microwave radiometer at the selected location, and calculate the effective brightness temperature of the moon based on the observed brightness temperature of the cosmic background, the correction coefficient of the lunar brightness temperature and the antenna efficiency weight, including: Among them, TB obs represents the observed brightness temperature of the microwave radiometer, TB cos_obs is the observed brightness temperature of the cosmic background, α is the correction coefficient of the brightness temperature of the moon, Represents the antenna efficiency weight coefficient.

10. A system for calculating the effective brightness temperature of the moon based on brightness temperature observation by a spaceborne microwave radiometer, characterized in that: The method for calculating the effective brightness temperature of the moon based on the brightness temperature observed by a satellite-borne microwave radiometer as described in any one of claims 1 to 9 above, the system comprising: a moon model brightness temperature calculation module, a coordinate matching module, an antenna efficiency weight calculation module, a moon brightness temperature correction coefficient calculation module, a cosmic background observation brightness temperature calculation module, and a moon effective brightness temperature calculation module; The lunar model brightness temperature calculation module is used to calculate the functional relationship between the lunar model brightness temperature and the lunar latitude and lunar phase; The coordinate matching module is used to match the lunar coordinate system with the satellite-borne microwave radiometer antenna coordinate system; The antenna efficiency weight calculation module is used to obtain the angle between the center of the moon at the selected position and the center of the field of view of the microwave radiometer antenna, as well as the azimuth of the moon entering the antenna to determine the position of the moon in the field of view of the antenna, and determine the azimuth range of the moon on the antenna radiation pattern according to the angle occupied by the moon in the field of view of the antenna, and calculate the antenna efficiency weight of the selected position; The lunar brightness temperature correction coefficient calculation module is used to simulate the lunar effective brightness temperature of the microwave radiometer at the selected position according to the lunar position and lunar phase, simulate the observed brightness temperature of the microwave radiometer at the selected position, and calculate the lunar brightness temperature correction coefficient according to the simulated lunar effective brightness temperature of the microwave radiometer, the simulated observed brightness temperature of the microwave radiometer and the antenna efficiency weight; The cosmic background observation brightness temperature calculation module is used to calculate the cosmic background observation brightness temperature of the selected position; The lunar effective brightness temperature calculation module is used to obtain the observed brightness temperature of the microwave radiometer at the selected position, and calculate the lunar effective brightness temperature based on the cosmic background observed brightness temperature, the lunar brightness temperature correction coefficient and the antenna efficiency weight.

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