Active and passive combined microwave remote sensing detection method for earth surface air pressure and air pressure profile

Abstract

The invention provides an active and passive combined microwave remote sensing detection method for earth surface air pressure and air pressure profile, which comprises the following steps: by combining a satellite-borne / airborne millimeter wave differential absorption radar and a satellite-borne / airborne microwave radiometer and utilizing oxygen differential absorption measurement, obtaining accurate land / ocean surface air pressure data; and the air pressure profile is further obtained by combining temperature and humidity profile data measured by a satellite-borne / airborne microwave radiometer. Compared with the prior art, the method has the advantages that active and passive microwaves are adopted for combined detection, detection information obtained by a microwave radiometer is complemented, calculation of the surface pressure is enhanced, and the surface pressure inversion precision is improved; according to the method, the surface pressure value can be obtained, and the atmospheric pressure profile can also be obtained. According to the method, accurate surface pressure detection can be realized, and the atmospheric pressure profile can be further deduced by combining the temperature profile and the humidity profile observed by the microwave radiometer.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of microwave remote sensing, and particularly relates to a method for detecting surface air pressure and air pressure profile by combined active and passive microwave remote sensing. BACKGROUND

[0002] Atmospheric pressure is a key driving factor for many geophysical parameters in the land / ocean-atmosphere energy cycle, and has an important influence on the formation and development of global climate and short-time weather phenomena (such as precipitation and wind field). Atmospheric pressure is also closely related to a large number of climate anomalies and natural disasters occurring at different time scales (such as El Nino, La Nina, squall, typhoon, tropical depression, rainstorm, drought, etc.). Therefore, the importance of global atmospheric pressure observation has gone beyond the field of scientific research, and it has a huge impact on society, economy, military and even survival safety.

[0003] In numerical weather prediction, tropical cyclone monitoring and analysis, and climatology research, surface air pressure data has very important applications. Numerical weather prediction needs surface air pressure data for initialization of the prediction model. The pressure field of a tropical cyclone reflects its intensity, scale, structure and dynamic characteristics, and is very important for the prediction, monitoring and analysis of the cyclone. The cyclone is a rapidly changing mesoscale weather system, and cyclone analysis requires high spatial and temporal resolution cyclone pressure field data. In addition, surface air pressure anomalies are closely related to climate anomalies, and climate prediction and global climate change research require long time series of global high-precision surface air pressure data.

[0004] At present, surface air pressure data is mainly obtained by in-situ observation means, and there is no satellite dedicated to atmospheric pressure observation, nor is there a business surface air pressure remote sensing retrieval product. With the rapid development of ground meteorological stations over the years, the spatial density of pressure observation has been greatly increased, forming a relatively complete pressure measurement system on land. However, remote areas and ocean areas are almost blank areas of pressure measurement due to the lack of land meteorological stations or sea surface buoy meteorological stations. In particular, the tropics, 75% of which are covered by oceans, have a dramatic local weather change and are a key factor affecting global climate, but the Tropical Atmosphere Ocean (TAO) project has only 10 detection stations that can obtain sea surface pressure data. The initialization of weather and climate models in this region results in large errors in the final prediction and simulation due to the lack of a large amount of accurate pressure data. In addition, in-situ observation means cannot obtain sea surface pressure under severe weather conditions such as tropical cyclones, and surface air pressure data is one of the important meteorological parameters for predicting and forecasting the intensity and path of tropical cyclones. The current commonly used method is radio sonde technology, but this technology, like buoy observation, can only provide limited spatial point measurements and cannot obtain the pressure field of the cyclone. At the same time, in-situ observation means have high economic costs and different detection accuracies, and it is difficult to meet the needs of global climate change and climate anomaly research.

[0005] In the oxygen absorption band, the vertical column total absorption information can be obtained by differential absorption measurement of strong and weak oxygen absorption frequencies. Since oxygen is uniformly mixed in the atmosphere, measuring the vertical column total absorption of oxygen can achieve the purpose of detecting surface air pressure. The current direct remote sensing method of surface air pressure is based on this detection mechanism, including spaceborne / airborne infrared oxygen A-band grating spectrometer, microwave radiometer and millimeter wave differential absorption radar.

[0006] In 1987, Mitchell and O'Brien proposed using a grating spectrometer to measure the solar radiation reflected by the sea surface at two different frequencies of the oxygen A absorption band, and then obtain the sea surface air pressure. However, the observation of the oxygen A absorption band is greatly affected by clouds and rain, and depends on solar radiation, so accurate measurement can only be achieved in clear skies and during the day.

[0007] In 2018, Zhang et al. (Zhang et al., 2018) of the National Space Science Center proposed using oxygen absorption band microwave radiometer observation to retrieve surface air pressure. However, due to the lack of high sensitivity channels for sea surface air pressure in existing spaceborne microwave radiometer payloads, and the fact that radiometer air pressure measurement is very sensitive to temperature profile changes, the sea surface air pressure measurement accuracy is not ideal in cloudy and rainy conditions. At the same time, passive measurement is sensitive to the characteristics of the surface radiation, and the resolution of spaceborne microwave radiometers is poor, which is easily affected by the heterogeneity of the land surface, resulting in poor accuracy of land surface air pressure measurement.

[0008] Lin et al. (Lin et al. 2005) of NASA Langley Research Center and Xu Xin et al. (Xu Xin and Zhu Di, 2019) of the National Space Science Center have carried out related theoretical and simulation research on the use of millimeter wave differential absorption radar to detect sea surface air pressure. However, since the air pressure retrieval based on active radar is significantly affected by temperature profile parameters, the accuracy of surface air pressure retrieval is not ideal. SUMMARY

[0009] The purpose of the present application is to solve the problem of poor accuracy of ocean / land surface air pressure measurement under non-clear conditions by the current remote sensing detection method of surface air pressure. A passive and active combined microwave remote sensing detection method of surface air pressure and air pressure profile is proposed. The complementary detection information of active and passive microwave detection is used to strengthen the calculation of surface air pressure, improve the accuracy of surface air pressure retrieval, and provide constraints for the vertical distribution of air pressure through active and passive combined detection, so as to obtain the vertical distribution information of air pressure.

[0010] In order to achieve the above object, the application provides a kind of surface air pressure and air pressure profile active-passive combined microwave remote sensing detection method, the method is combined by spaceborne / airborne millimeter wave differential absorption radar and spaceborne / airborne microwave radiometer, obtains land / ocean surface air pressure data using oxygen differential absorption measurement, further obtains air pressure profile in combination with temperature and humidity profile data measured by spaceborne / airborne microwave radiometer;The method comprises:

[0011] Step 1) according to the relationship between the multiple sets of radar echo signal power differences in the strong oxygen absorption band and its adjacent window band measured by spaceborne / airborne millimeter wave differential absorption radar and the surface air pressure, temperature profile, humidity profile and cloud and rain profile, establish the surface air pressure active-passive combined inversion algorithm;

[0012] Step 2) according to the multi-channel radar echo signal power measured by spaceborne / airborne millimeter wave differential absorption radar, the surface air pressure active coarse estimate value and the cloud and rain profile are obtained by inversion;And through the radiation brightness temperature value in the set range near oxygen absorption band and water vapor absorption line measured by spaceborne / airborne passive microwave radiometer, temperature profile, humidity profile data and surface air pressure passive coarse estimate value are obtained by inversion;

[0013] Step 3) the multi-channel radar echo signal power measured by spaceborne / airborne millimeter wave differential absorption radar and the surface air pressure active coarse estimate value, and the temperature profile, humidity profile data inverted by passive radiometer, are input into the surface air pressure active-passive combined inversion algorithm, to obtain the surface air pressure active inversion result;

[0014] Step 4) according to the deviation distribution characteristics of the surface air pressure passive coarse estimate value and the surface air pressure active inversion result, establish the surface air pressure passive deviation correction model;

[0015] Step 5) the surface air pressure active inversion result and the surface air pressure passive coarse estimate value are input into the surface air pressure passive deviation correction model, and the deviation correction of passive inversion result is carried out, to obtain the surface air pressure passive inversion result;

[0016] Step 6) according to the static equilibrium equation, the atmospheric pressure profile is derived from the surface air pressure active / passive inversion result, and the temperature profile and humidity profile passive inversion result.

[0017] As an improvement of the above method, in step 1) the relationship between the multiple sets of radar echo signal power differences in the strong oxygen absorption band and its adjacent window band measured by spaceborne / airborne millimeter wave differential absorption radar and the surface air pressure, temperature profile, humidity profile and cloud and rain profile is represented by the following formula:

[0018]

[0019] where λ1 and λ2 are the wavelengths of two measurement channels of spaceborne / airborne millimeter-wave differential absorption radar; P r (λ1) is the radar return signal power of the 1st measurement channel; C(λ1) = P T A e / 4π, P T is the radar transmit power, A e is the effective aperture of the antenna, the calculation formula is λ1 2 G / 4π, G is the antenna gain; σ 0 (λ1, θ) is the backscattering coefficient of the ground; θ represents the incidence angle of the radar beam; s represents the height of the radar; P(s) is the distribution of atmospheric pressure with height s; T(s) is the distribution of atmospheric temperature with height s; v O (s), v w (s), v L (s) respectively represent the volume mixing ratio of oxygen, water vapor, and liquid water; α O (λ1, s, T(s), P(s)), α w (λ1, s, T(s), P(s)), α L (λ1, s, T(s), P(s)) respectively represent the mass absorption coefficients of oxygen, water vapor, and liquid water in the 1st measurement channel; r is the projection of the distance between the radar illumination area and the radar in the vertical direction.

[0020] As an improvement of the above method, the establishment of the ground surface atmospheric pressure active-passive combined inversion algorithm comprises:

[0021] Step 1-1) According to the relationship between the multiple sets of radar return signal power differences in the strong oxygen absorption band and its adjacent window frequency band measured by the spaceborne / airborne millimeter-wave differential absorption radar and the ground surface atmospheric pressure, temperature profile, humidity profile, and cloud and rain profile, a forward simulation model for measuring the ground surface atmospheric pressure by the spaceborne / airborne millimeter-wave differential absorption radar is established;

[0022] Step 1-2) Based on the Bayesian optimal estimation theory, a ground surface atmospheric pressure active-passive combined inversion algorithm is established in combination with the forward simulation model; the input of the algorithm is the multiple sets of radar return signal power differences in the strong oxygen absorption band and its adjacent window frequency band measured by the radar, the auxiliary data includes the initial estimated value of the ground surface atmospheric pressure and the true values of the atmospheric temperature profile, humidity profile, and cloud and rain profile, and the output is the ground surface atmospheric pressure;

[0023] Step 1-3) The Gauss-Newton iteration format is used to iteratively solve the ground surface atmospheric pressure value until the result meets the set convergence condition, and the ground surface atmospheric pressure inversion result is output.

[0024] As an improvement of the above method, the step 3) comprises:

[0025] Step 3-1) inputting the active coarse estimation of the surface pressure obtained by the millimeter wave differential absorption radar observation as an initial estimation of the surface pressure into the surface pressure active-passive joint inversion algorithm to start the physical iteration process;

[0026] Step 3-2) inputting the cloud and rain profile data obtained by the millimeter wave differential absorption radar window channel observation as the true value of the atmospheric cloud and rain profile into the surface pressure active-passive joint inversion algorithm to correct the contribution of cloud and rain attenuation and scattering;

[0027] Step 3-3) inputting the temperature profile and humidity profile data obtained by the passive radiometer as the true value of the atmospheric temperature profile and humidity profile into the surface pressure active-passive joint inversion algorithm to quantitatively estimate the contribution of the atmospheric temperature and humidity to the echo signal power between different channels;

[0028] Step 3-4) inputting the measured multi-channel radar echo signal power difference of the spaceborne / airborne millimeter wave differential absorption radar into the surface pressure active-passive joint inversion algorithm as the input of the surface pressure active-passive joint inversion algorithm, combining the active coarse estimation of the surface pressure, the cloud and rain profile data, the temperature profile and humidity profile data, to obtain the active inversion result of the surface pressure.

[0029] As an improvement of the above method, the step 4) comprises:

[0030] Step 4-1) using the temperature profile and humidity profile data obtained by the passive radiometer to eliminate the abnormal passive coarse estimation result of the surface pressure according to the fluid consistency principle;

[0031] Step 4-2) establishing a bias correction model for the passive inversion of the surface pressure according to the bias distribution characteristics of the passive coarse estimation of the surface pressure and the active inversion result of the surface pressure after quality control.

[0032] As an improvement of the above method, the step 6) comprises:

[0033] inputting the active / passive inversion result of the surface pressure and the passive inversion result of the temperature profile and humidity profile into the following formula to obtain the atmospheric pressure profile:

[0034]

[0035] wherein P(s) represents the pressure of the atmosphere at the height s; P S represents the active / passive inversion result of the surface pressure; M represents the air molecular weight of 29 g / mol; R represents the gas molar constant of 8.314 J / (mol·K); g represents the gravity acceleration of 9.8 m / s 2 .

[0036] Compared with the prior art, the application has the advantages that:

[0037] 1、The method of the present application uses the joint detection of microwave radiometer and millimeter wave differential absorption radar to estimate the surface air pressure, which can effectively improve the inversion accuracy compared with the surface air pressure field detection results of microwave radiometer or millimeter wave differential absorption radar alone.

[0038] 2、The method of the present application can not only obtain the surface air pressure value, but also obtain the atmospheric pressure profile. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The flow chart of the active and passive joint microwave remote sensing detection method of surface air pressure and pressure profile is shown. DETAILED DESCRIPTION

[0040] The technical solutions of the present application will be described in detail below with reference to the drawings.

[0041] In view of the lack of existing surface air pressure remote sensing detection means and the problem that the measurement accuracy of the proposed remote sensing detection scheme for marine / terrestrial surface air pressure under non-clear sky conditions is not ideal, the present application provides an active and passive joint microwave remote sensing detection method of surface air pressure and pressure profile, which realizes complementary detection information by active and passive microwave joint detection, strengthens the calculation of surface air pressure, improves the inversion accuracy of surface air pressure, and provides a constraint for the vertical distribution of pressure by active and passive joint detection, so as to realize the acquisition of vertical distribution information of pressure.

[0042] In combination with Figure 1 The active and passive joint microwave remote sensing detection method of surface air pressure and pressure profile of the present application combines satellite-borne / airborne millimeter wave differential absorption radar and satellite-borne / airborne microwave radiometer, uses oxygen differential absorption measurement to obtain accurate terrestrial / marine surface air pressure data, and further obtains the pressure profile in combination with the temperature and humidity profile data measured by the satellite-borne / airborne microwave radiometer.

[0043] Step 1: Establishing a ground surface pressure active-passive joint inversion algorithm according to the relationship between the multiple sets of radar echo signal power differences in the strong oxygen absorption band and its adjacent window band measured by the spaceborne / airborne millimeter wave differential absorption radar and the ground surface pressure, temperature profile, humidity profile, cloud and rain profile;

[0044] The relationship between the multiple sets of radar echo signal power differences in the strong oxygen absorption band and its adjacent window band measured by the spaceborne / airborne millimeter wave differential absorption radar and the ground surface pressure, temperature profile, humidity profile, cloud and rain profile can be expressed by the following formula:

[0045]

[0046] Wherein, P r is the radar echo signal power, C(λ)=P T A e / 4π, λ1 and λ2 are the wavelengths of two measurement channels of the spaceborne / airborne millimeter wave differential absorption radar, P T is the radar transmitting power, A e is the effective aperture of the antenna, the calculation formula is λ 2 G / 4π, G is the antenna gain, σ 0 is the ground surface backscattering coefficient, θ represents the radar beam incidence angle, s represents the radar height, P(s) is the distribution of atmospheric pressure with height s, T(s) is the atmospheric temperature profile, v O , v w , v L respectively represent the oxygen, water vapor and liquid water volume mixing ratio, α O , α w , α L respectively represent the oxygen, water vapor and liquid water mass absorption coefficient, and r is the distance between the radar illumination area and the projection of the radar in the vertical direction.

[0047] In step 1, the ground surface pressure active-passive joint inversion algorithm is established, and the step further includes the following processing method:

[0048] Step 1-1: Establishing a forward simulation model of the spaceborne / airborne millimeter wave differential absorption radar measuring the ground surface pressure according to formula (1);

[0049] Step 1-2: Based on the Bayesian optimal estimation theory, a ground surface pressure active-passive joint inversion algorithm is established combined with the forward model of step 1-1, the input of the algorithm is the multiple sets of radar echo signal power differences in the strong oxygen absorption band and its adjacent window band measured by the radar, the auxiliary data includes the initial estimated value of the ground surface pressure and the true values of the atmospheric temperature profile, humidity profile and cloud and rain profile, and the output is the ground surface pressure;

[0050] Step 1-3: Gauss-Newton iteration format is used to iteratively solve the surface pressure value until the result meets the convergence condition, and the surface pressure inversion result is output.

[0051] Step 2: According to the multi-channel radar echo signal power measured by the spaceborne / airborne millimeter wave differential absorption radar, the active coarse estimation value of the surface pressure and the cloud and rain profile are obtained; and through the oxygen absorption band and the water vapor absorption line near the radiation brightness temperature value measured by the spaceborne / airborne passive microwave radiometer, the temperature profile, humidity profile inversion data and passive coarse estimation value of the surface pressure are obtained.

[0052] The relationship between the multi-channel radar echo signal power measured by the spaceborne / airborne millimeter wave differential absorption radar and the active coarse estimation value of the surface pressure is as follows:

[0053]

[0054] Wherein, λ1 and λ2 are the wavelengths of two measurement channels of the spaceborne / airborne millimeter wave differential absorption radar, α o (λ) represents the mass absorption coefficient of oxygen, C(λ) = P T (λ)A e (λ)4π, P T is the radar transmitting power, A e is the effective aperture of the antenna, v O represents the volume mixing ratio of oxygen in the atmosphere, g represents the acceleration of gravity, P o represents the active coarse estimation value of the surface pressure, P r (λ) represents the radar echo power, represents the logarithm of the ratio of the echo signal power of two channels of the radar, that is, the differential absorption index.

[0055] According to the above relationship, the active coarse estimation value of the surface pressure P o can be obtained by the differential of the multi-channel radar echo signal power measured by the spaceborne / airborne millimeter wave differential absorption radar.

[0056] The radar reflectivity factor can be obtained from the radar echo signal power measured by the window channel of the spaceborne / airborne millimeter wave differential absorption radar, and the cloud and rain profile can be further obtained.

[0057] The millimeter wave differential absorption radar transmits a pulse and receives a return, and the power P r received by the window channel at a distance R (R is the distance between the radar illumination area and the radar along the radar beam direction) is as follows: m0

[0058]

[0059] ​where C is a radar constant, and K is a constant defined by the refractive index m. Thus, given the system parameters of the radar, the distance R, and the refractive index m, the radar reflectivity factor Z can be obtained from the received power of the return signal by the window channel m0 (R). According to the reflectivity factor, the cloud water profile and the rain rate profile can be retrieved.

[0060] The relationship between the oxygen absorption band radiance brightness temperature measured by the spaceborne / airborne microwave radiometer and the passive coarse estimation value P s of the surface air pressure is as follows:

[0061]

[0062] According to the above relationship, the oxygen absorption band radiance brightness temperature measured by the spaceborne / airborne microwave radiometer can be used to retrieve the passive coarse estimation value P s of the surface air pressure and the temperature profile T(P). Wherein f represents the frequency, and ε(f, θ) represents the surface emissivity; P s represents the passive coarse estimation value of the surface air pressure; P represents the pressure profile; T(P) represents the vertical distribution of temperature with pressure P; T s represents the surface temperature; v O represents the volume mixing ratio of oxygen in the atmosphere, and g represents the acceleration of gravity; θ represents the beam incidence angle;

[0063] The atmospheric humidity profile can also be retrieved from the radiance brightness temperature near the water vapor absorption line measured by the spaceborne / airborne microwave radiometer, for example, the atmospheric humidity profile data obtained by the 183GHz water vapor absorption line near the radiance brightness temperature observation of the Fengyun-3 satellite microwave humidity meter.

[0064] Step 3: input the multi-channel radar return signal power measured by the spaceborne / airborne millimeter wave differential absorption radar and the active coarse estimation value of the surface air pressure, as well as the temperature profile and humidity profile data retrieved by the passive radiometer, into the established joint retrieval algorithm to obtain the active retrieval result of the surface air pressure;

[0065] This step specifically includes the following processing method:

[0066] Step 3-1: input the active coarse estimation value of the surface air pressure retrieved from the millimeter wave differential absorption radar observation as the initial estimation value of the surface air pressure into the surface air pressure active-passive joint retrieval algorithm established in step 1 to start the physical iteration process;

[0067] Step 3-2: input the cloud and rain profile data retrieved from the millimeter wave differential absorption radar window channel observation as the true value of the atmospheric cloud and rain profile into the surface air pressure active-passive joint retrieval algorithm established in step 1 to correct the contribution of cloud and rain attenuation and scattering and improve the air pressure retrieval accuracy under non-clear sky conditions;

[0068] Step 3-3: The temperature profile and humidity profile data retrieved by the passive radiometer are input into the surface pressure active / passive combined retrieval algorithm established in Step 1 as the true values of the atmospheric temperature profile and humidity profile, to quantitatively estimate the contribution of the atmospheric temperature and humidity to the echo signal power of different channels, and further improve the calculation accuracy of the surface pressure.

[0069] Step 3-4: The multi-channel radar echo signal power difference measured by the spaceborne / airborne millimeter wave differential absorption radar is input into the surface pressure active / passive combined retrieval algorithm, and the auxiliary retrieval data obtained in Steps 3-1, 3-2 and 3-3 are combined to obtain the active retrieval result of the surface pressure.

[0070] Step 4: According to the deviation distribution characteristics of the passive coarse estimation value of the surface pressure and the active retrieval result of the surface pressure, a passive deviation correction model of the surface pressure is established.

[0071] Step 4-1: The temperature profile and humidity profile data retrieved by the passive radiometer are used to perform quality control on the passive coarse estimation result of the surface pressure according to the fluid consistency principle, and the abnormal passive coarse estimation result of the surface pressure is removed.

[0072] Step 4-2: According to the deviation distribution characteristics of the passive coarse estimation value of the surface pressure and the active retrieval result of the surface pressure, a passive deviation correction model of the surface pressure is established.

[0073] Step 5: The active retrieval result of the surface pressure and the passive coarse estimation value of the surface pressure are input into the deviation correction model to perform deviation correction on the passive retrieval result, and the passive retrieval result of the surface pressure is obtained.

[0074] Step 6: The active / passive retrieval result of the surface pressure and the passive retrieval result of the temperature profile and humidity profile are used to derive the atmospheric pressure profile.

[0075] The active / passive retrieval result of the surface pressure and the passive retrieval result of the temperature profile and humidity profile are input into the following formula to obtain the atmospheric pressure profile, and the process can be represented as:

[0076]

[0077] wherein P(s) represents the atmospheric pressure at height s, P S refers to the active / passive retrieval result of the surface pressure, M represents the air molecular weight of 29 g / mol, R represents the gas molar constant of 8.314 J / (mol·K), T(s) is the distribution of the atmospheric temperature with height s, and g refers to the gravitational acceleration of 9.8 m / s 2 .

[0078] In summary, this embodiment provides an active and passive combined microwave remote sensing detection method for surface air pressure and pressure profile, which realizes the complementarity of detection information through active and passive microwave combined detection, strengthens the solution of surface air pressure, improves the accuracy of surface air pressure inversion, and provides constraints on the vertical distribution of air pressure through active and passive combined detection, thereby realizing the acquisition of air pressure vertical distribution information.

[0079] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of this application and are not intended to limit the scope of the present invention. Although this application has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of this application do not depart from the spirit and scope of the technical solutions of this application and should be encompassed by the claims of this application.

Claims

1. A combined active and passive microwave remote sensing method for detecting surface air pressure and pressure profiles, comprising: combining a satellite-borne / airborne millimeter-wave differential absorption radar with a satellite-borne / airborne microwave radiometer to obtain land / ocean surface air pressure data using oxygen differential absorption measurements; and combining this with temperature and humidity profile data measured by the satellite-borne / airborne microwave radiometer to further obtain a pressure profile; the method comprising: Step 1) establishing a joint active and passive inversion algorithm for surface pressure based on the relationship between the power differences of multiple groups of radar echo signals within the strong oxygen absorption band and its adjacent window frequency band measured by satellite-borne / airborne millimeter-wave differential absorption radar and the surface pressure, temperature profile, humidity profile, and cloud and rain profile; Step 2) inverting an active rough estimate of surface pressure and a cloud and rain profile based on the multi-channel radar echo signal power measured by a satellite-borne / airborne millimeter-wave differential absorption radar; and inverting the radiation brightness temperature within a set range near the oxygen absorption band and the water vapor absorption line measured by a satellite-borne / airborne passive microwave radiometer to obtain temperature profile, humidity profile data, and a passive rough estimate of surface pressure; Step 3) inputting the multi-channel radar echo signal power and active rough estimate of surface pressure measured by satellite / airborne millimeter-wave differential absorption radar, as well as the temperature profile and humidity profile data inverted by the passive radiometer, into the active and passive joint inversion algorithm of surface pressure to obtain the active inversion result of surface pressure; Step 4) establishing a passive surface pressure deviation correction model based on the deviation distribution characteristics between the passive rough estimate of surface pressure and the active surface pressure inversion result; Step 5) inputting the active inversion result of surface pressure and the passive rough estimate of surface pressure into the passive bias correction model of surface pressure to perform bias correction on the passive inversion result to obtain the passive inversion result of surface pressure; Step 6) The atmospheric pressure profile is derived from the active / passive inversion results of the surface pressure, as well as the passive inversion results of the temperature profile and the humidity profile, according to the static equilibrium equation.

2. The method according to claim 1, wherein, The relationship between the power differences of multiple groups of radar echo signals in the strong oxygen absorption band and its adjacent window frequency band measured by the spaceborne / airborne millimeter-wave differential absorption radar in step 1) and the surface pressure, temperature profile, humidity profile, and cloud and rain profile is expressed by the following formula: Wherein, λ1 and λ2 are the wavelengths of two measurement channels of the spaceborne / airborne millimeter-wave differential absorption radar; P r (λ1) is the radar echo signal power of the first measurement channel; C(λ1)=P T A e / 4π,P T is the radar transmission power, A e is the effective aperture of the antenna, and the calculation formula is λ1 2 G / 4π, G is the antenna gain; σ 0 (λ1, θ) is the surface backscatter coefficient; θ is the radar beam incident angle; s is the radar altitude; P(s) is the distribution of atmospheric pressure with altitude s; T(s) is the distribution of atmospheric temperature with altitude s; v O (s), v w (s), v L (s) represents the volume mixing ratio of oxygen, water vapor and liquid water respectively; α O (λ1, s, T(s), P(s)), α w (λ1, s, T(s), P(s)), α L (λ1, s, T(s), P(s)) represent the mass absorption coefficients of oxygen, water vapor, and liquid water in the first measurement channel, respectively; r represents the projection of the distance between the radar illumination area and the radar in the vertical direction.

3. The method according to claim 1, wherein, The method of establishing the active and passive combined inversion algorithm for surface air pressure includes: Step 1-1) establishing a forward simulation model for measuring surface pressure using a spaceborne / airborne millimeter-wave differential absorption radar based on the relationship between power differences of multiple radar echo signals within the strong oxygen absorption band and its adjacent window frequency band measured by the spaceborne / airborne millimeter-wave differential absorption radar and the surface pressure, temperature profile, humidity profile, and cloud and rain profile; Steps 1-2) Based on Bayesian optimal estimation theory and combined with a forward simulation model, a joint active and passive inversion algorithm for surface pressure is established. The algorithm inputs are the power differences of multiple radar echo signals within the strong oxygen absorption band and its adjacent window frequency band measured by radar, and auxiliary data include an initial estimate of surface pressure and the true values ​​of the atmospheric temperature profile, humidity profile, and cloud and rain profile. The output is surface pressure. Step 1-3) The surface pressure value is iteratively solved in a Gauss-Newton iterative format until the result meets the set convergence condition, and the surface pressure inversion result is output.

4. The method according to claim 1, wherein, The step 3) comprises: Step 3-1) The active coarse estimation value of the surface pressure inverted by the millimeter wave differential absorption radar observation is input into the surface pressure active-passive joint inversion algorithm as the initial estimation value of the surface pressure, for starting the physical iteration process; Step 3-2) The cloud and rain profile data inverted by the millimeter wave differential absorption radar window channel observation are input into the surface pressure active-passive joint inversion algorithm as the true value of the atmospheric cloud and rain profile, for correcting the contribution of cloud and rain attenuation and scattering; Step 3-3) The temperature profile and humidity profile data inverted by the passive radiometer are input into the surface pressure active-passive joint inversion algorithm as the true value of the atmospheric temperature profile and humidity profile, for quantitatively estimating the contribution of the atmospheric temperature and humidity to the echo signal power between different channels; Step 3-4) The measured multi-channel radar echo signal power difference of the spaceborne / airborne millimeter wave differential absorption radar is input into the surface pressure active-passive joint inversion algorithm as the input of the surface pressure active-passive joint inversion algorithm, and the active coarse estimation value of the surface pressure, the cloud and rain profile data, the temperature profile and humidity profile data are combined to obtain the active inversion result of the surface pressure.

5. The method according to claim 1, wherein, The step 4) comprises: Step 4-1) The temperature profile and humidity profile data inverted by the passive radiometer are used to eliminate the abnormal passive coarse estimation result of the surface pressure according to the fluid consistency principle; Step 4-2) A bias correction model of the passive inversion of the surface pressure is established according to the bias distribution characteristics of the passive coarse estimation value of the surface pressure and the active inversion result of the surface pressure.

6. The method according to claim 1, wherein, The step 6) comprises: The active / passive inversion result of the surface pressure and the passive inversion result of the temperature profile and humidity profile are input into the following formula to obtain the atmospheric pressure profile: where P(s) represents the pressure of the atmosphere at height s; P S active / passive inversion results of surface pressure; M represents the air molecular weight of 29 g / mol; R represents the gas molar constant of 8.314 J / (mol·K); g represents the gravity acceleration of 9.8 m / s 2 .

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