Method for improving observation integral water vapor content of microwave radiometer

Abstract

The invention belongs to the technical field of water vapor content observation by a microwave radiometer, and particularly relates to a method for improving integral water vapor content observation by the microwave radiometer. The problem that an existing radiometer is low in water vapor observation precision, and high-precision forecasting of cloudy and rainy weather is difficult is solved. The method comprises the following steps: S1, according to a troposphere atmosphere microwave remote sensing principle, atmospheric refraction error correction and a principle of observing water vapor content by using a microwave radiometer, determining different channels required by inversion of the water vapor content, namely a water vapor absorption channel and a liquid water channel; s2, an ITU-R P.676 proposal: an attenuation model of radio waves in the atmosphere is used for calculation, and the channel selected in the step S1 and the corresponding weight function, the total atmospheric attenuation, the ground atmospheric absorption coefficient and the atmospheric average temperature are calculated; and S3, substituting the calculated amount in the step S2 and the brightness temperature observed by the microwave radiometer into a calculation formula for observing the atmospheric moisture delay of the troposphere by the microwave radiometer, and calculating the atmospheric moisture delay of the troposphere.

Description

Technical Field

[0001] The invention belongs to the technical field of water vapor content observation by microwave radiometers, and in particular relates to a method for improving the integrated water vapor content observed by a microwave radiometer. Background Art

[0002] Although water vapor accounts for a small fraction of the atmosphere, it is the most active component. Water vapor is a key component of the atmosphere, and its proportion within a given region varies with time, space, and meteorological conditions. Because water vapor molecules are polar molecules with an electric dipole, their interaction with the electric field of incident electromagnetic waves can attenuate these waves. Furthermore, the atmosphere can produce a refractive effect on information systems such as radio tracking and navigation. Although water vapor only accounts for 0.1% to 4% of the atmosphere, the refraction error of radio waves caused by water vapor accounts for over 10% of the total refraction error in the troposphere. The atmospheric water vapor content and spatial distribution are highly variable, making it a major component of the residual in atmospheric refraction error correction. Furthermore, the atmospheric water vapor content is crucial for cloud formation, cloud droplet growth, precipitation formation, and rainfall intensity. Furthermore, the phase transition of water vapor in the cloud-sky generates a high latent heat of phase change, significantly affecting atmospheric vertical stability and the structure and evolution of storm systems. Therefore, the atmospheric water vapor content is crucial for research on radio wave propagation characteristics and weather forecasting.

[0003] Atmospheric water vapor content is a key meteorological parameter describing water vapor and a key indicator influencing rainfall formation. It is crucial for the forecasting and diagnosis of precipitation weather processes. Atmospheric water vapor content also plays a crucial role in atmospheric processes at various temporal and spatial scales, serving as a crucial input factor for severe weather prediction and climate change models. Numerous studies have shown that factors such as altitude, geographic latitude, and human activities influence the spatiotemporal distribution of atmospheric water vapor content in my country. Accurately determining atmospheric water vapor content is not only crucial for accurately forecasting precipitation and severe weather, but also holds crucial importance in fields such as weather modification, weather forecasting, aerospace, and aviation. Therefore, the study of atmospheric water vapor content has become a crucial topic in meteorology and the environment.

[0004] The present invention conducts technical research on a method for improving the water vapor content observed by a microwave radiometer. Experiments verify the feasibility and effectiveness of the method, forming a method for improving the water vapor content observed by a microwave radiometer. This method can be extended and applied to all domestic radiometer equipment, which is of great significance for the future realization of high-precision weather forecasts as well as aerospace, aviation and other fields. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a method for improving the integrated water vapor content observed by a microwave radiometer, so as to solve the problem that the existing radiometer has low accuracy in observing water vapor, and thus it is difficult to make high-precision forecasts of rainy weather.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for improving the integrated water vapor content observed by a microwave radiometer comprises the following steps:

[0008] S1, based on the principles of microwave remote sensing of the tropospheric atmosphere, atmospheric refraction error correction, and the principle of observing water vapor content using microwave radiometers, determines the different channels required for inverting water vapor content, namely, the water vapor absorption channel f1 and the liquid water channel f2;

[0009] S2, using the ITU-R P.676 Recommendation: Attenuation model of radio waves in the atmosphere, calculate the weight function W corresponding to the channels f1 and f2 selected in step S1 m , total atmospheric attenuation, ground atmospheric absorption coefficient and average atmospheric temperature;

[0010] S3, substituting the calculated value in step S2 and the brightness temperature observed by the microwave radiometer into the calculation formula of the tropospheric atmospheric wet delay observed by the microwave radiometer to calculate the tropospheric atmospheric wet delay;

[0011] S4, substituting the tropospheric atmospheric wet delay into the equivalent formula of tropospheric atmospheric wet delay and tropospheric atmospheric water vapor content to obtain the tropospheric atmospheric water vapor content;

[0012] S5, determine the error in the obtained tropospheric atmospheric water vapor content.

[0013] Furthermore, in meteorology, it means the water vapor content formed at the bottom of the air column after all the water vapor in the air column condenses and falls; water vapor content refers to the mass of water vapor contained in the atmospheric column of any unit cross-sectional area, that is, the water vapor content is the integrated water vapor calculated from the ground to the upper air. The full English name is Integreted Water Vapor, abbreviated as IWV, and the unit is kg / m 2 This application defines the vertical integrated water vapor above the ground microwave radiometer receiver, the full English name Integreted WaterVapor, which represents the total amount of water vapor in the vertical air column per unit area, in kg / m 2 , also known as integrated water vapor;

[0014]

[0015] Where S is the water vapor density of each layer in the water vapor density profile ρ v The corresponding height;

[0016] The wet term delay of the tropospheric path is calculated by directly observing the brightness temperature using the multi-channel microwave radiometer, and then the atmospheric integrated water vapor is calculated from the wet delay.

[0017] Tropospheric atmospheric path wet term delay ΔL w :

[0018]

[0019] Where: P w is the partial pressure of water vapor in the atmosphere, unit is hPa, T is the absolute temperature, unit is K;

[0020] k'2=16.48(K / hPa);

[0021] k3=(3.776±0.014)×10 5 (K 2 / hPa);

[0022] is the compressibility coefficient of moist air in the atmosphere, t (℃);

[0023] And let T m The weighted average temperature of the atmosphere in the vertical direction, in K, hereinafter referred to as the atmospheric average temperature:

[0024]

[0025] T m Use ground temperature to estimate:

[0026] T m =a+bT s Formula 4;

[0027] Where: T s is the ground temperature, unit K, T m The regression coefficients a and b are obtained by regression using the sounding data from the local meteorological bureau;

[0028] Substituting formula 3 into formula 2, it can be written as:

[0029]

[0030] The total amount of water vapor in a vertical air column per unit area, i.e., the integrated water vapor, is obtained using the gas state equation:

[0031]

[0032] Where: ΔL zw is the vertical path wet term delay in the atmospheric troposphere, R w =461.495(J / (K·kg)),1J=1(kg·m2 ) / s 2 is the specific gas constant of water vapor;

[0033] According to Formula 1-Formula 6:

[0034] IWV=πΔL zw kg / m 2 Formula 7;

[0035] in: Formula 7 is applied to tropospheric atmospheric slant paths, that is, Formula 7 is applicable to all paths in the entire troposphere;

[0036] Calculation of tropospheric wet delay using direct observations of brightness temperature from multi-channel microwave radiometers:

[0037]

[0038] T m1,2 =T m Formula 11;

[0039] Where: k = 1.7201 × 10 -3 , ρ v is the water vapor density profile, unit is g / m 3 , T is the atmospheric temperature profile, unit K, T S Cosmic background radiation brightness temperature, T B1，2 、T m1,2 are respectively the atmospheric radiation brightness temperature and the atmospheric average temperature measured by the microwave radiometer f1 and f2 frequency channels along the oblique path of radio wave propagation, W m is the weight function, α 01 ,α 02 are the oxygen molecule absorption coefficients at the operating frequencies f1 and f2, α v1 ,α v2 are the water vapor molecular absorption coefficients at the working frequencies f1 and f2, τ1 and τ2 are the total atmospheric attenuation at the working frequencies f1 and f2, α 01 , α 02 , α v1 , α v2 , τ1 and τ2 can be obtained by the line-by-line calculation method in Recommendation ITU-R-676: Attenuation of radio waves in atmospheric gases and related effects;

[0040] W m The weight function can be obtained by using the ground water vapor absorption coefficient from Recommendation ITU-R-676 and substituting it into Formula 9;

[0041] Recommendation ITU-R-676: For radio waves in the frequency range of 1-350 GHz, in the approximate calculation of atmospheric gas attenuation, the following algorithm can be used to estimate the water vapor absorption coefficient from sea level to 10 km altitude:

[0042] For attenuation in water vapor, the atmospheric characteristic attenuation value α v , the unit dB / km is calculated as follows:

[0043]

[0044]

[0045] Formula 12;

[0046] in:

[0047]

[0048] Where: f is the frequency in GHz, r p =p / 1013, r t =288 / (273+t), where p is pressure in hPa, t is temperature in °C, and ρ is water vapor density in g / m 3 ;

[0049] The root mean square error of the atmospheric integrated water vapor value observed by the radiometer relative to the true integrated water vapor value calculated by the sounding profile is calculated as follows:

[0050]

[0051] Where: σ is the inversion error of the atmospheric column integrated water vapor content, S is the number of samples compared with the radiosonde data, ≥30 groups, V t is the atmospheric column integrated water vapor content calculated from the radiosonde measurement, V f It is the atmospheric column integrated water vapor content measured by the atmospheric temperature and humidity profiler.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] Based on the principles of microwave remote sensing of the tropospheric atmosphere, atmospheric refraction error correction and water vapor content measurement theory, and atmospheric absorption and attenuation theory, the accuracy of water vapor content observed by existing radiometers in the test area is analyzed to improve the accuracy of water vapor content observed by existing radiometers, thereby preparing for high-precision forecasts of rainy weather. This invention can significantly promote the accuracy of integrated water vapor content observed by domestically produced microwave radiometers in my country. At the same time, it improves the meteorological center forecasters' understanding of weather dynamics and provides more accurate weather forecasts for decision-making by operational departments. In addition, some research results can be promoted and applied in various fields such as microwave remote sensing, detection, and battlefield perception, while also improving the level of independent research and development of microwave radiometers in my country. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0055] Figure 1 1. It is a schematic flow chart of a method for improving the integrated water vapor content observed by a microwave radiometer according to the present invention;

[0056] Figure 2 This is a schematic diagram comparing integrated water vapor samples observed by the microwave radiometer at Wudu sounding station in accordance with the present invention. DETAILED DESCRIPTION

[0057] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0058] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention but is merely representative of selected embodiments of the present invention.

[0059] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field under the description before making any creative work shall fall within the scope of protection of the present invention.

[0060] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0061] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0062] like Figure 1 As shown:

[0063] A method for improving the integrated water vapor content observed by a microwave radiometer comprises the following steps:

[0064] S1, based on the principles of microwave remote sensing of the tropospheric atmosphere, atmospheric refraction error correction, and the principle of observing water vapor content using microwave radiometers, determines the different channels required for inverting water vapor content, namely, the water vapor absorption channel f1 and the liquid water channel f2;

[0065] According to the principle of microwave remote sensing of the tropospheric atmosphere and the existing channels of the QFW-6000 microwave radiometer developed by the 22nd Institute of China Electronics Technology Group Corporation, the water vapor absorption channel f1 and the liquid water channel f2 required for the water vapor content inversion method described in this application are determined;

[0066] S2, using the ITU-R P.676 Recommendation: Attenuation model of radio waves in the atmosphere, calculate the weight function W corresponding to the channels f1 and f2 selected in step S1 m , total atmospheric attenuation, ground atmospheric absorption coefficient and average atmospheric temperature;

[0067] Substitute the ground temperature, humidity, and pressure observed by the QFW-6000 microwave radiometer developed by the 22nd Institute of China Electronics Technology into the ITU-RP.676 Recommendation, that is, formula 9-formula 18 to obtain the weight function W corresponding to the channel in step S1 m At the same time, the ground temperature, humidity and pressure observed by the QFW-6000 microwave radiometer developed by the 22nd Institute of China Electronics Technology Group Corporation are introduced into the line-by-line calculation method of the attenuation and related effects of radio waves in atmospheric gases in the ITU-R P.676 Recommendation to obtain the total atmospheric attenuation τ1 and τ2 corresponding to the channels f1 and f2 selected in step S1; the ground oxygen molecule absorption coefficient α corresponding to f1 and f2 01 and α 02; The ground oxygen molecule absorption coefficient α corresponding to f1 and f2 v1 and α v2 At the same time, the ground temperature observed by the QFW-6000 microwave radiometer developed by the 22nd Institute of China Electronics Technology Group Corporation is substituted into Formula 4 to obtain T m1,2 are the average atmospheric temperatures of the microwave radiometer frequency channels f1 and f2, respectively;

[0068] S3, substituting the calculated value in step S2 and the brightness temperature observed by the microwave radiometer into the calculation formula of the tropospheric atmospheric wet delay observed by the microwave radiometer to calculate the tropospheric atmospheric wet delay;

[0069] The observed brightness temperatures corresponding to the f1 and f2 channels of the QFW-6000 microwave radiometer developed by the 22nd Institute of China Electronics Technology Group Corporation and the α values ​​corresponding to the selected channels f1 and f2 obtained in step S2 are calculated. 01 , α 02 , α v1 , α v2 , τ1, τ2, W m and T m1,2 Substituting into Formula 8-Formula 11, we can obtain the tropospheric atmospheric wet delay corresponding to the observed brightness temperature of channels f1 and f2, in meters.

[0070] S4, substituting the tropospheric atmospheric wet delay into the equivalent formula of tropospheric atmospheric wet delay and tropospheric atmospheric water vapor content to obtain the tropospheric atmospheric water vapor content;

[0071] The tropospheric atmospheric water vapor content is obtained by substituting the tropospheric atmospheric wet delay corresponding to the observed brightness temperature of the f1 and f2 channels of the QFW-6000 microwave radiometer developed by the 22nd Institute of China Electronics Technology Group Corporation into Formula 7.

[0072] S5, determine the error in the obtained tropospheric atmospheric water vapor content.

[0073] There are many parameters for evaluating the quality of an algorithm. Here, in order to evaluate the feasibility and accuracy of the inversion described in this application, the root mean square error is used as the error statistic.

[0074] When conducting error analysis, the atmospheric integrated water vapor calculated from the sounding data of the sounding station in the test area is used as the true atmospheric integrated water vapor value, and the atmospheric integrated water vapor obtained by the algorithm is compared with the sounding atmospheric integrated water vapor. The root mean square error, the root mean square error of the atmospheric integrated water vapor observed by the radiometer relative to the true integrated water vapor value calculated from the sounding profile, is calculated as follows:

[0075]

[0076] Where: σ is the inversion error of the atmospheric column integrated water vapor content, S is the number of samples compared with the radiosonde data, ≥30 groups, V tis the atmospheric column integrated water vapor content calculated from the radiosonde measurement, V f It is the atmospheric column integrated water vapor content measured by the atmospheric temperature and humidity profiler.

[0077] In meteorology, it means the amount of water vapor at the bottom of an air column after all the water vapor in the air column condenses and falls. Water vapor content refers to the mass of water vapor contained in an atmospheric column per unit cross-sectional area. That is, the water vapor content is the integral water vapor calculated from the ground to the upper air. The full name of the English word is Integreted Water Vapor, abbreviated as IWV, and the unit is kg / m 2 This application defines the vertical integrated water vapor above the ground-based microwave radiometer receiver, which is called Integreted Water Vapor, and represents the total amount of water vapor in the vertical air column per unit area, in kg / m 2 , also known as integrated water vapor;

[0078]

[0079] Where S is the water vapor density of each layer in the water vapor density profile ρ v The corresponding height;

[0080] The traditional algorithm for measuring atmospheric integrated water vapor using real-time remote sensing with microwave radiometers is to obtain the atmospheric water vapor density by integrating the atmospheric water vapor density profile obtained by inversion. This algorithm is based on inversion, and the accuracy of the measured atmospheric integrated water vapor depends on the accuracy of the water vapor density profile inverted by microwave radiometer remote sensing. The following introduces a new algorithm for calculating atmospheric integrated water vapor using real-time remote sensing data from microwave radiometers. That is, the tropospheric path wet term delay is calculated using the direct observation brightness temperature of the microwave radiometer's multi-channel, and the atmospheric integrated water vapor is then calculated from the wet delay;

[0081] Tropospheric atmospheric path wet term delay ΔL w As an important component of tropospheric delay:

[0082]

[0083] Where: P w is the partial pressure of water vapor in the atmosphere, unit is hPa, T is the absolute temperature, unit is K;

[0084] k'2=16.48(K / hPa);

[0085] k3=(3.776±0.014)×10 5 (K 2 / hPa);

[0086] is the compressibility coefficient of moist air in the atmosphere, t (℃);

[0087] Z w -1 ≈1, and let T m The weighted average temperature of the atmosphere in the vertical direction, in K, hereinafter referred to as the atmospheric average temperature:

[0088]

[0089] T m Use ground temperature to estimate:

[0090] T m =a+bT s Formula 4;

[0091] Where: T s is the ground temperature, unit K, T m The regression coefficients a and b are obtained by regression using the sounding data from the local meteorological bureau. This application uses the historical sounding data from Qingdao and obtains a = 0.81 and b = 44.6.

[0092] Substituting formula 3 into formula 2, it can be written as:

[0093]

[0094] The total amount of water vapor in a vertical air column per unit area, i.e., the integrated water vapor, is obtained using the gas state equation:

[0095]

[0096] Where: ΔL zw is the vertical path wet term delay in the atmospheric troposphere, R w =461.495(J / (K·kg)),1J=1(kg·m 2 ) / s 2 is the specific gas constant of water vapor;

[0097] According to Formula 1-Formula 6:

[0098] IWV=πΔL zw kg / m 2 Formula 7;

[0099] in: Formula 7 is applied to tropospheric atmospheric slant paths, that is, Formula 7 is applicable to all paths in the entire troposphere;

[0100] Calculation of tropospheric wet delay using direct observations of brightness temperature from multi-channel microwave radiometers:

[0101]

[0102] T m1,2 =T m Formula 11;

[0103] Where: k = 1.7201 × 10 -3 , ρ v is the water vapor density profile, unit is g / m 3 , T is the atmospheric temperature profile, unit K, T S Cosmic background radiation brightness temperature, T B1，2 、T m1,2 are respectively the atmospheric radiation brightness temperature and the atmospheric average temperature measured by the microwave radiometer f1 and f2 frequency channels along the oblique path of radio wave propagation, W m is the weight function, α 01 ,α 02 are the oxygen molecule absorption coefficients at the operating frequencies f1 and f2, α v1 ,α v2 are the water vapor molecular absorption coefficients at the working frequencies f1 and f2, τ1 and τ2 are the total atmospheric attenuation at the working frequencies f1 and f2, α 01 , α 02 , α v1 , α v2 , τ1 and τ2 can be obtained by the line-by-line calculation method in Recommendation ITU-R-676: Attenuation of radio waves in atmospheric gases and related effects;

[0104] W m The weight function can be obtained by using the ground water vapor absorption coefficient from Recommendation ITU-R-676 and substituting it into Formula 9;

[0105] Recommendation ITU-R-676: For radio waves in the frequency range of 1-350 GHz, in the approximate calculation of atmospheric gas attenuation, the following algorithm can be used to estimate the water vapor absorption coefficient from sea level to 10 km altitude:

[0106] For attenuation in water vapor, the atmospheric characteristic attenuation value α v , the unit dB / km is calculated as follows:

[0107]

[0108] Formula 12;

[0109] in:

[0110]

[0111] Where: f is the frequency in GHz, r p =p / 1013, r t=288 / (273+t), where p is pressure in hPa, t is temperature in °C, and ρ is water vapor density in g / m 3 .

[0112] Taking the measured data of a radiometer at a sounding station in the 2023 Microwave Radiometer Civilian Product Project as an example, the effectiveness of this application method is verified.

[0113] Radiometer equipment and a sounding station were co-located for observation in a certain area. The observation data covers the evening of June 22, 2023, and the morning of October 20, 2023. There are 240 groups of valid samples available for comparison. After removing the data that were not available in both the sounding and the equipment, 196 groups of comparison samples were obtained. After removing the data of rainy days and abnormal soundings, 124 groups of data are left for comparison. The comparison samples are shown in Figure 2 . Figure 2 The red solid line is the actual observation value of a microwave radiometer; the blue solid line is the actual integrated water vapor value calculated from the sounding data of a sounding station; the green solid line is the new integrated water vapor value obtained by using the brightness temperature observed by a microwave radiometer into the patented algorithm; the root mean square error of the actual observation value of the microwave radiometer in a certain area obtained by statistics using formula 16 is: 4.19kg / m 2 The root mean square error of the new integrated water vapor value obtained by using the brightness temperature observed by microwave radiometer in a certain area and applying the proposed method is: 2.72 kg / m 2 .from Figure 2 It can be seen that the method of this application is effective.

[0114] The present invention has been described above by way of example with reference to the accompanying drawings. It is apparent that the specific implementation of the present invention is not limited to the above-described embodiments. Those skilled in the art may make various modifications or variations to the present invention without departing from the technical concept of the present invention, and such modifications or variations shall naturally fall within the scope of protection of the present invention.

Claims

1. A method for improving the integrated water vapor content observed by a microwave radiometer, characterized by: The following steps are involved: S1, based on the principle of microwave remote sensing of the tropospheric atmosphere, atmospheric refraction error correction and the principle of observing water vapor content using microwave radiometers, determines the different channels required for inverting water vapor content, namely the water vapor absorption channel f1 and the liquid water channel f2; S2, using the ITU-R P.676 Recommendation: Attenuation model of radio waves in the atmosphere, calculate the weight function W corresponding to the channels f1 and f2 selected in step S1 m , total atmospheric attenuation, ground atmospheric absorption coefficient and average atmospheric temperature; S3, substituting the calculated amount in step S2 and the brightness temperature observed by the microwave radiometer into the calculation formula of the tropospheric atmospheric wet delay observed by the microwave radiometer to calculate the tropospheric atmospheric wet delay; S4, substituting the tropospheric atmospheric wet delay into the equivalent formula of tropospheric atmospheric wet delay and tropospheric atmospheric water vapor content to obtain the tropospheric atmospheric water vapor content; S5, determine the error in the obtained tropospheric atmospheric water vapor content.

2. The method for improving the integrated water vapor content observed by a microwave radiometer according to claim 1, characterized in that: The following steps are involved: In meteorology, it means the amount of water vapor at the bottom of an air column after all the water vapor in the air column condenses and falls. Water vapor content refers to the mass of water vapor contained in an atmospheric column per unit cross-sectional area. Water vapor content is the integral water vapor obtained by integrating from the ground to the upper air. It is defined as the vertical integral water vapor above the ground-based microwave radiometer receiver, which represents the total amount of water vapor in the vertical air column per unit area, and is measured in kg / m 2 , also known as integrated water vapor; Where S is the water vapor density of each layer in the water vapor density profile ρ v The corresponding height; The wet term delay of the tropospheric path is calculated by directly observing the brightness temperature using the multi-channel microwave radiometer, and then the atmospheric integrated water vapor is calculated from the wet term delay. Tropospheric atmospheric path wet term delay ΔL w : Where: P w is the partial pressure of water vapor in the atmosphere, unit is hPa, T is the absolute temperature, unit is K; k'2=16.48(K / hPa); k3=(3.776±0.014)×10 5 (K 2 / hPa); is the compressibility coefficient of moist air in the atmosphere, t unit is °C; And let T m The weighted average temperature of the atmosphere in the vertical direction, unit K, hereinafter referred to as the atmospheric average temperature: T m Use ground temperature to estimate: T m =a+bT s Formula 4: Where: T s is the ground temperature, unit K, T m The regression coefficients a and b are obtained by regression using the sounding data from the local meteorological bureau; Substituting formula 3 into formula 2, it can be written as: The total amount of water vapor per unit area in a vertical column of air, that is, the integrated water vapor, is obtained using the gas state equation: Where: ΔL zw is the vertical path wet term delay in the atmospheric troposphere, R w =461.495(J / (K·kg)),1J=1(kg·m 2 ) / s 2 is the specific gas constant of water vapor; According to Formula 1-Formula 6: IWV = πΔL zw kg / m 2 Equation 7; in: Formula 7 is applied to tropospheric atmospheric slant paths, that is, Formula 7 is applicable to all paths in the entire troposphere; The tropospheric wet term delay is calculated using direct observations of brightness temperature from a microwave radiometer using multiple channels: T m1,2 =T m Formula 11; Where: k = 1.7201 × 10 -3 ,ρ v is the water vapor density profile, unit is g / m 3 , T is the atmospheric temperature profile, unit K, T S Cosmic background radiation brightness temperature, T B1，2 、T m1,2 are respectively the atmospheric radiation brightness temperature and the atmospheric average temperature measured by the microwave radiometer f1 and f2 frequency channels along the oblique path of radio wave propagation, W m is the weight function, α 01 ,α 02 are the oxygen molecule absorption coefficients at the operating frequencies f1 and f2, α v1 ,α v2 are the water vapor molecular absorption coefficients at the working frequencies f1 and f2, τ1 and τ2 are the total atmospheric attenuation at the working frequencies f1 and f2, α 01 , α 02 , α v1 , α v2 , τ1 and τ2 can be obtained by the line-by-line calculation method in Recommendation ITU-R-676: Attenuation of radio waves in atmospheric gases and related effects; W m The weight function is obtained from the ground water vapor absorption coefficient in Recommendation ITU-R-676 and is substituted into Formula 9 to obtain: Recommendation ITU-R-676: For radio waves in the frequency range of 1-350 GHz, in the approximate calculation of atmospheric gas attenuation, the following algorithm is used to estimate the water vapor absorption coefficient from sea level to 10 km altitude: For attenuation in water vapor, the atmospheric characteristic attenuation value α v , unit dB / km, calculated as follows: Formula 12; in: η1=0.955r p r t 0.68 +0.006ρ Formula 13; η2=0.735r p r t 0.5 +0.0353 r t 4 ρ Equation 14; Where: f is the frequency in GHz, r p =p / 1013, r t =288 / (273+t), where p is pressure in hPa, t is temperature in °C, and ρ is water vapor density in g / m 3 ; The root mean square error of the atmospheric integrated water vapor value observed by the radiometer relative to the true integrated water vapor value calculated by the sounding profile is calculated as follows: Where: σ is the inversion error of the atmospheric column integrated water vapor content, S is the number of samples compared with the radiosonde data, ≥30 groups, V t is the atmospheric column integrated water vapor content calculated from the radiosonde measurement, V f It is the atmospheric column integrated water vapor content measured by the atmospheric temperature and humidity profiler.

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