Doppler precipitation radar precipitation and three-dimensional wind field synchronous inversion method and system

Abstract

The invention belongs to the field of microwave remote sensing, and relates to a Doppler precipitation radar precipitation and three-dimensional wind field synchronous inversion method and system. The Doppler precipitation radar precipitation and three-dimensional wind field synchronous inversion method comprises the following steps: determining a reflectivity factor of an observation area through echo power of a Doppler precipitation radar; according to the reflectivity factor, determining a rainfall area and calculating the size of rainfall particles; calculating the vertical falling speed of the precipitation particles according to the size of the precipitation particles; calculating the radial velocity of precipitation particles according to the echo phase of the Doppler precipitation radar; removing the vertical falling speed of the precipitation particles to obtain the radial movement speed of the precipitation particles caused by the wind field; and according to the rainfall particle radial motion speed caused by the wind field, a radar observation geometry and a three-dimensional wind field inversion algorithm are combined, and a three-dimensional wind field of the rainfall area is obtained through inversion. By adopting the method provided by the invention, the wind field inversion precision is improved.

Description

Technical Field

[0001] The present invention belongs to the field of microwave remote sensing, and particularly relates to a method and system for synchronously retrieving precipitation and three-dimensional wind field of a Doppler precipitation radar. Background Art

[0002] The measurement of precipitation and atmospheric wind field is of great significance in meteorology and weather forecasting. Precipitation is a key link in the earth's water cycle and is crucial for water resource management, agricultural production, and the maintenance of ecosystems. The atmospheric wind field, as an important dynamic factor driving weather systems, not only controls the generation and transport of precipitation but also is closely related to the evolution of weather systems such as cyclones and anticyclones. By accurately measuring precipitation and wind field, the interaction mechanism between them can be revealed, providing reliable data support for weather forecasting, climate change research, and disaster prevention and mitigation.

[0003] Currently, significant progress has been made in precipitation measurement technologies, covering various observation means such as ground, air, and satellite. Weather radars retrieve precipitation intensity and structure through the spatial distribution of radar reflectivity factors and can achieve large-scale real-time monitoring. Satellite observations provide important support for global precipitation measurement, especially in areas where it is difficult to deploy ground instruments such as the ocean and mountainous regions. Satellites based on microwave and infrared sensors (such as TRMM, GPM) can capture the spatial distribution and intensity of precipitation, with the characteristics of wide coverage and high time resolution. However, precipitation radars cannot measure the velocity of targets and cannot obtain velocity information.

[0004] Currently, the main means for detecting atmospheric wind fields mainly include spaceborne infrared "cloud-drift wind" technology, ground-based wind profiler radars, spaceborne lidar wind radars, etc. Due to the limitation of penetration ability, spaceborne infrared "cloud-drift wind" technology cannot obtain the vertical distribution information of the atmospheric wind field within clouds; ground-based wind profiler radars are restricted by natural conditions such as terrain and are difficult to deploy in ocean and remote land areas, making it impossible to achieve global networked observations; spaceborne lidar wind radars, such as "Aladin" carried on the "Aeolus" satellite, can accurately detect the atmospheric wind field in clear sky areas. However, since lasers cannot penetrate clouds, the "Aeolus" satellite cannot obtain the in-cloud wind field data in cloud-covered areas, and the global average cloud coverage rate exceeds 66%, and the cloud coverage rate in coastal areas can reach 80% - 90%, resulting in a large amount of key wind field data being missing. Conical scanning Doppler radars have the ability to detect the three-dimensional wind field within clouds, but the calculation accuracy of the three-dimensional wind field depends on the quality of the radial velocity data of target particles. If the radial velocity data contains a large amount of information in areas without meteorological targets, it will lead to a decrease in inversion accuracy, and it is necessary to determine the precipitation area through radar reflectivity factor measurement data and screen the radial velocity in the precipitation area. In addition, for Doppler precipitation radars, the measured radial velocity includes the vertical falling velocity of particles caused by gravity, so the influence needs to be removed during the inversion process to obtain an accurate estimate of the three-dimensional wind field. Summary of the Invention

[0005] The object of the present invention is to overcome the defects of the prior art and propose a method and system for synchronously retrieving precipitation and three-dimensional wind field by a Doppler precipitation radar.

[0006] In view of this, the present invention proposes a method for synchronously retrieving precipitation and three-dimensional wind field by a Doppler precipitation radar, including:

[0007] Step 1) Determine the reflectivity factor of the observation area through the echo power of the Doppler precipitation radar;

[0008] Step 2) Determine the precipitation area and calculate the precipitation particle size according to the reflectivity factor;

[0009] Step 3) Calculate the vertical falling velocity of the precipitation particles through the precipitation particle size;

[0010] Step 4) Calculate the radial velocity of the precipitation particles according to the echo phase of the Doppler precipitation radar; remove the vertical falling velocity of the precipitation particles to obtain the radial motion velocity of the precipitation particles caused by the wind field;

[0011] Step 5) Invert the three-dimensional wind field of the precipitation area according to the radial motion velocity of the precipitation particles caused by the wind field, combined with the radar observation geometry and the three-dimensional wind field inversion algorithm.

[0012] Preferably, the Doppler precipitation radar is a spaceborne or airborne radar, and adopts a working mode of multiple pulse repetition frequencies to expand the measurable radial velocity range, and adopts a conical scanning system.

[0013] Preferably, the reflectivity factor Z of the observation area in step 1) m is:

[0014]

[0015] where r is the distance from the observation area to the radar, λ is the electromagnetic wave wavelength, |K| is the dielectric constant, G at is the transmitting antenna gain, G ar is the receiving antenna gain, θ 0a is the cross-track beam width, θ 0c is the along-track beam width, c is the speed of light, τ is the transmitted pulse width, P t is the transmitted power, P r is the received power.

[0016] Preferably, step 2) includes:

[0017] According to the reflectivity factor Z of the observation area m , determine the precipitation intensity I from the empirical relationship between the radar reflectivity factor and the precipitation intensity:

[0018] Z m = 200I 1.6

[0019] Determine the attenuation parameter Λ according to the precipitation intensity I as follows:

[0020] Λ = 4.11I -0.21

[0021] Through the attenuation parameter Λ, the normalized number concentration constant N0 determines the distribution N(D) of the raindrop particle diameter D as follows:

[0022] N(D) = N0e -ΛD

[0023] Determine the average particle size D through numerical integration mean as follows:

[0024]

[0025] Preferably, the vertical falling velocity v(D) of the precipitation particles in step 3) is:

[0026] v(D) = 1300D mean 0.5

[0027] where D mean is the average particle size of the particles.

[0028] Preferably, the calculation process of the echo phase of the Doppler precipitation radar in step 4) includes:

[0029] For the signal emitted by the Doppler radar, the baseband echo s(t) obtained after down-conversion by the receiver is:

[0030] s(t) = exp(-j2π[f c τ - 0.5α(t - τ) 2 )

[0031] α = W / T p

[0032] where f c is the carrier frequency, t is the echo time within the pulse, τ is the echo time shift, α is the frequency modulation slope, T p is the pulse width, W is the signal bandwidth; j represents the imaginary part;

[0033] Construct the reference function s ref (t) as follows:

[0034] s ref (t) = exp(-j2π[fcτ0 - 0.5α(t - τ0) 2 )

[0035] Among them, τ0 is the time shift of the reference signal;

[0036] The pulse compression signal s is obtained through Fourier transform out as:

[0037] s out = IFFT{FFT[s(t)]·conj[FFT[s ref (t)]]}

[0038] Among them, FFT is the Fourier transform, IFFT is the inverse Fourier transform, and conj represents taking the conjugate of a complex number;

[0039] Take two adjacent pulse compression signals A = s out1 , B = s out2 , N is the number of relevant points, then the correlation coefficient ρ(A, B) of the adjacent pulse compression signals is:

[0040]

[0041] Among them, μ A , μ B and σ A , σ B are the mean and standard deviation of A and B respectively;

[0042] Take the phase of ρ(A, B) which is the echo phase.

[0043] Preferably, the calculation process of the radial velocity V target of the precipitation particles in step 4) includes:

[0044] According to the phases corresponding to two pulse repetition frequencies, the folded radial velocities are respectively: Among them, V u1 , V u2 are the maximum unambiguous velocities corresponding to the respective pulse repetition intervals, V1 + MV u1 = V2 + MV u2 = V, M is the folding number, V is the true velocity, let then the unfolded true velocity V is:

[0045]

[0046] Among them, is the extended maximum unambiguous velocity:

[0047] For the maximum unambiguous velocity after the double PRF expansion calculated at each observed attitude, calculate \(n_1\) and \(n_2\) that satisfy the following equation:

[0048]

[0049] According to \(n_1\) and \(n_2\), calculate the unfolded radial velocity \(V\) corresponding to each single pulse repetition interval 1True , \(V\) 2True :

[0050] \(V\) 1True = \(V_1 + 2n_1V\) u1

[0051] \(V\) 2True = \(V_2 + 2n_2V\) u2

[0052] Calculate the radial velocity \(V\) according to the following formula True :

[0053]

[0054] Obtain the projection \(V\) of the motion velocity of the moving platform where the radar is located in the observation direction according to the following formula platform_proj :

[0055] \(V\) platform_proj = \(V\) platform ·\(V\) observe

[0056] where \(V\) platform is the representation of the platform motion in the geographical coordinate system, which consists of velocities in three directions:

[0057] \(V\) platform = (\(V\) north , \(V\) east , \(V\) up )

[0058] where \(V\) north is the northward velocity of the platform motion, \(V\) east is the eastward velocity of the platform motion, \(V\) up is the upward velocity of the platform motion;

[0059] \(V\) observe is the observation vector of the radar:

[0060]

[0061] where is the angle between the radar observation direction and the positive direction of the z-axis; \(\theta\) is the angle between the projection of the radar observation direction on the xy plane and the positive direction of the x-axis;

[0062] Obtain the radial velocity \(V\) of the precipitation particles according to the following formulatarget :

[0063] V target = V True - V platform_proj .

[0064] Preferably, the radial movement speed V of the precipitation particles caused by the wind field in step 4) wind is:

[0065]

[0066] Preferably, the three-dimensional wind field in the precipitation area in step 5) is:

[0067]

[0068] wherein, V x , V y , V z are respectively the velocities of the three-dimensional atmospheric wind field in the x, y, and z directions, and p′ represents the transpose matrix of the observation matrix p.

[0069]

[0070] wherein, and θ n are the elevation angle and azimuth angle corresponding to the nth observation in the target area, n > 3.

[0071] On the other hand, the present invention provides a Doppler precipitation radar precipitation and three-dimensional wind field synchronous inversion system, including:

[0072] A reflectivity factor calculation module for determining the reflectivity factor of the observation area through the echo power of the Doppler precipitation radar;

[0073] A precipitation particle size calculation module for determining the precipitation area and calculating the precipitation particle size according to the reflectivity factor;

[0074] A vertical falling velocity calculation module for calculating the vertical falling velocity of the precipitation particles through the precipitation particle size;

[0075] A radial movement velocity calculation module for calculating the radial velocity of the precipitation particles according to the echo phase of the Doppler precipitation radar; removing the vertical falling velocity of the precipitation particles to obtain the radial movement velocity of the precipitation particles caused by the wind field;

[0076] An inversion module for inversely obtaining the three-dimensional wind field of the precipitation area according to the radial movement velocity of the precipitation particles caused by the wind field, in combination with the radar observation geometry and the three-dimensional wind field inversion algorithm.

[0077] Compared with the prior art, the advantages of the present invention are:

[0078] The present invention provides a method for synchronously retrieving precipitation and three-dimensional wind fields of a Doppler precipitation radar. By using the measured data of radar reflectivity factors, precipitation regions are determined, and the radial velocity measurements in the precipitation regions are screened to improve the accuracy of wind field retrieval. Additionally, information on the particle size of precipitation particles is obtained from the reflectivity factors, and then the vertical falling velocity of the particles is obtained. By subtracting the falling velocity of the particles from the calculated radial velocity, the radial velocity caused by the wind is obtained, thereby improving the accuracy of vertical wind speed retrieval. Description of the Drawings

[0079] Figure 1 is a flowchart of the method for synchronously retrieving precipitation and three-dimensional wind fields of the Doppler precipitation radar of the present invention. Detailed Embodiments

[0080] The object of the embodiment of the present invention is to provide a method for synchronously retrieving precipitation and three-dimensional wind fields of a Doppler precipitation radar. By using the echo power of the precipitation radar, the reflectivity factor of the observation area is determined; by using the radar reflectivity factor, the precipitation area is determined and the precipitation particle size is calculated; according to the precipitation particle size, the vertical falling velocity of the precipitation particles is calculated; according to the echo phase of the precipitation radar, the radial velocity of the precipitation particles is calculated; the vertical falling velocity of the precipitation particles is removed to obtain the radial movement velocity of the precipitation particles caused by the wind field; according to the radial movement velocity of the precipitation particles caused by the wind field, combined with the radar observation geometry and the three-dimensional wind field inversion algorithm, the three-dimensional wind field of the precipitation area is inverted.

[0081] The method specifically includes:

[0082] Step 1): By using the echo power of the precipitation radar, the reflectivity factor of the observation area is determined.

[0083] The Doppler precipitation radar is a spaceborne / airborne radar, which adopts a working mode of multiple pulse repetition frequencies (PRF) to expand the measurable radial velocity range and adopts a conical scanning system.

[0084] Step 2): According to the radar reflectivity factor obtained in Step 1), the precipitation area is determined and the precipitation particle size is calculated.

[0085] Step 2) further includes:

[0086] By using the empirical relationship between the radar reflectivity factor and the precipitation intensity, the precipitation intensity I is determined:

[0087] Z m = 200I 1.6

[0088] By using the precipitation intensity I, the attenuation parameter Λ is determined:

[0089] Λ = 4.11I -0.21

[0090] Through the attenuation parameter Λ and the normalized number concentration constant N0 (8000 m -3 mm -1 ), determine the distribution N(D) of the raindrop particle diameter D:

[0091] N(D) = N0e -ΛD

[0092] Determine the average particle size D through numerical integration mean :

[0093]

[0094] Step 3): Calculate the vertical falling velocity of the precipitation particles from the precipitation particle sizes obtained in Step 2).

[0095] Step 3) further includes:

[0096] According to the average particle size D of the particles mean , determine the terminal falling velocity v(D) of the particles:

[0097] v(D) = 1300D mean 0.5

[0098] Use the pulse pair interference method to calculate the interference phase of the target, and use the dual-pulse repetition frequency algorithm to calculate the radial velocity of the target. Subtract the terminal falling velocity of the particles from the calculated radial velocity to obtain the radial motion velocity of the precipitation particles caused by the wind field.

[0099] Step 4): Calculate the radial velocity of the precipitation particles from the echo phase of the precipitation radar; remove the vertical falling velocity of the precipitation particles obtained in Step 3) to obtain the radial motion velocity of the precipitation particles caused by the wind field;

[0100] Step 5): According to the radial motion velocity of the precipitation particles caused by the wind field obtained in Step 4), combined with the radar observation geometry and the three-dimensional wind field inversion algorithm, invert the three-dimensional wind field of the precipitation area.

[0101] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0102] Embodiment 1

[0103] Embodiment 1 of the present invention provides a method for synchronously retrieving precipitation and three-dimensional wind field by a Doppler weather radar. Based on the echo power of the precipitation radar, the reflectivity factor of the observation area is determined; based on the radar reflectivity factor, the precipitation area is determined and the precipitation particle size is calculated; according to the precipitation particle size, the vertical falling velocity of the precipitation particles is calculated; according to the echo phase of the precipitation radar, the radial velocity of the precipitation particles is calculated; the vertical falling velocity of the precipitation particles is removed to obtain the radial movement velocity of the precipitation particles caused by the wind field; based on the radial movement velocity of the precipitation particles caused by the wind field, combined with the radar observation geometry and the three-dimensional wind field inversion algorithm, the three-dimensional wind field of the precipitation area is retrieved.

[0104] The method specifically includes:

[0105] Step 1) Based on the echo power P of the precipitation radar, the reflectivity factor of the observation area is determined. The radar reflectivity factor Z is calculated by the following formula: r : m

[0106]

[0107] where r is the distance between the target and the radar, λ is the electromagnetic wave wavelength, |K| is the dielectric constant, G at is the transmitting antenna gain, G ar is the receiving antenna gain, θ 0a is the cross-track beam width, θ 0c is the along-track beam width, c is the speed of light, τ is the transmitted pulse width, P t is the transmitted power, and P r is the received power.

[0108] Step 2) Based on the radar reflectivity factor obtained in Step 1, the precipitation area is determined and the precipitation particle size is calculated.

[0109] Take the logarithm of the radar reflectivity factor obtained in Step 1 to obtain dBZ:

[0110] dBZ = 10log 10 (Z m )

[0111] Among all the observation data, filter out the data with dBZ value greater than 10 dB and determine it as the precipitation area.

[0112] When the dBZ value ranges from 10 to 40 dB, the precipitation intensity I (unit: mm / h) is determined according to the following formula:

[0113] Z m = 200I 1.6

[0114] When the dBZ value is greater than 40 dB, the precipitation intensity I is determined according to the following formula

[0115] Z m = 486I 1.37

[0116] Through the precipitation intensity I, the attenuation parameter Λ is determined as follows:

[0117] Λ = 4.11I -0.21

[0118] Through the attenuation parameter Λ and the normalized number concentration constant N0 (8000 m -3 mm -1 ), the distribution N(D) of the raindrop particle diameter D is determined:

[0119] N(D) = N0e -ΛD

[0120] The average particle diameter D is determined through numerical integration mean (unit: mm):

[0121]

[0122] Step 3) Through the precipitation particle size obtained in Step 2), the vertical falling velocity of the precipitation particles is calculated.

[0123] For the precipitation scenario, when its dBZ value is greater than 10 dB, according to the average particle diameter D of the particles mean , the vertical falling velocity v(D) of the particles can be determined:

[0124] v(D) = 1300(D mean *0.1) 0.5

[0125] where D mean is in the unit of mm and v(D) is in the unit of cm / s.

[0126] Step 4) The echo phase is calculated from the original echo signal of the precipitation radar;

[0127] The signal emitted by the radar is a linear frequency modulation pulse signal, as shown in the following formula:

[0128] s(t) = exp(j2π[f c t + 0.5αt 2 ), 0 ≤ t ≤ T p , α = W / T p

[0129] where, f c is the carrier frequency, α is the frequency modulation slope, T pis the pulse width, W is the signal bandwidth, t is the echo time within the pulse, and τ is the echo time shift.

[0130] The radar echo from a point target at R (delay τ = 2R / c) can be expressed as:

[0131] s(t) = exp(j2π[f c (t - τ) + 0.5α(t - τ) 2 )

[0132] The baseband echo obtained after down-conversion by the receiver can be expressed as:

[0133] s(t) = exp(-j2π[f c τ - 0.5α(t - τ) 2 )

[0134] The reference function of the matched filter constructed according to the transmit signal bandwidth, duration, and sampling rate can be expressed as:

[0135] s ref (t) = exp(-j2π[f c τ0 - 0.5α(t - τ0) 2 )

[0136] where τ0 is the reference signal time shift.

[0137] The pulse compression signal s out obtained through Fourier transform can be expressed as:

[0138] s out = IFFT{FFT[s(t)]·conj[FFT[s ref (t)]]}

[0139] Taking two adjacent pulse compression signals A = s out1 , B = s out2 , and N being the number of correlation points, the correlation coefficient of the adjacent pulse compression signals is:

[0140]

[0141] where μ A , μ B and σ A , σ B , are the mean and standard deviation of A and B respectively. ρ(A,B) is a complex number, and its phase is the interference phase.

[0142] Step 5) Calculate the radial velocity of the precipitation particles from the echo phase;

[0143] For the same target speed, different pulse repetition intervals will result in different phase values. By using the different phase values at two pulse repetition frequencies, the extended radial velocity can be calculated.

[0144] For the folded radial velocity, the phases at two pulse repetition frequencies are respectively: The corresponding folded radial velocities are respectively: where, V u1 , V u2 are the maximum unambiguous velocities corresponding to the pulse repetition intervals respectively. And V1 + MV u1 = V2 + MV u2 = V, M is the folding number, and V is the true speed. Let Then the true speed after unfolding can be calculated by the following formula:

[0145]

[0146] where is the extended maximum unambiguous velocity:

[0147] For the extended maximum unambiguous velocity calculated at each observation attitude, use the following formula to calculate n1 and n2 that make the equation hold:

[0148]

[0149] Using the calculated n1n2, calculate the unfolded radial velocities V 1True , V 2True :

[0150] V 1True = V1 + 2n1V u1

[0151] V 2True = V2 + 2n2V u2

[0152] Then average the unfolded radial velocities corresponding to each single pulse repetition interval calculated, and calculate the radial velocity V True :

[0153]

[0154] Since the radar is located on a moving platform, the calculated radial velocity is affected by both the target motion and the platform motion. After calculating the radial velocity, it is necessary to exclude the influence of the platform motion, and the platform motion V patformIn the geodetic coordinate system, the positive direction of the x-axis points to the geodetic north, the positive direction of the y-axis points to the geodetic east, and the positive direction of the z-axis is perpendicular to the plane where the x-axis and y-axis are located and points to the sky. V platform It consists of velocities in three directions: V north : the northward velocity of the platform movement, V east the eastward velocity of the platform movement, V up : the upward velocity of the platform movement:

[0155] V platform =(V north ,V east ,V up )

[0156] The platform movement affects the velocity measurement in the observation direction. The observation vector V of the radar observe is:

[0157]

[0158] where is the observation elevation angle at the satellite / aircraft, which is the angle between the radar observation direction and the positive direction of the z-axis; θ is the azimuth angle, which is the angle between the projection of the radar observation direction on the xy plane and the positive direction of the x-axis.

[0159] Then the projection V of the platform movement velocity in the observation direction platform_proj is calculated by the following formula:

[0160] V platform_proj =V platform ·V observe

[0161] The radial velocity V of the precipitation particles target is the calculated radial velocity V True minus the projection V of the platform movement velocity in the observation direction platform :

[0162] V target =V True -V platform_proj

[0163] Step 6) Remove the vertical falling velocity of the precipitation particles obtained in step 3) to obtain the radial movement velocity of the precipitation particles caused by the wind;

[0164] Subtract the projection of the precipitation vertical velocity v(D) obtained in step 3) in the radial direction from the target radial velocity V target to obtain the radial wind speed V wind , which can be expressed as

[0165]

[0166] Step 7) According to the radial motion velocity of precipitation particles caused by the wind field obtained in Step 6), combined with the radar observation geometry and the three-dimensional wind field inversion algorithm, the three-dimensional wind field of the precipitation area is inverted.

[0167] After obtaining the radial motion velocity of precipitation particles caused by the wind field, through more than three independent observations of the target area, the wind speed and wind direction in the target area are calculated by the least squares method.

[0168] Assume that the elevation angle and azimuth angle corresponding to the i-th (i≥3) observation in the target area are respectively expressed as and θ i , i represents the i-th observation quantity, and there are n observation quantities in total. Then the observation matrix is expressed by the following formula:

[0169]

[0170] The three-dimensional wind field of the atmosphere is calculated according to the following formula:

[0171]

[0172] Among them, V x , V y , V z are the velocities of the three-dimensional wind field of the atmosphere in the x, y, and z directions respectively. The definitions of the three directions are given in Step 5), and V wind is the radial wind speed calculated in Step 6), and p′ represents the transpose matrix of p.

[0173] Embodiment 2

[0174] Embodiment 2 of the present invention provides a Doppler precipitation radar precipitation and three-dimensional wind field synchronous inversion system, which is implemented based on the method of Embodiment 1. The system includes:

[0175] A reflectivity factor calculation module, which is used to determine the reflectivity factor of the observation area through the echo power of the Doppler precipitation radar;

[0176] A precipitation particle size calculation module, which is used to determine the precipitation area and calculate the precipitation particle size according to the reflectivity factor;

[0177] A vertical falling velocity calculation module, which is used to calculate the vertical falling velocity of precipitation particles through the precipitation particle size;

[0178] A radial motion velocity calculation module, which is used to calculate the radial velocity of precipitation particles according to the echo phase of the Doppler precipitation radar; remove the vertical falling velocity of precipitation particles to obtain the radial motion velocity of precipitation particles caused by the wind field;

[0179] An inversion module, configured to inversely obtain a three-dimensional wind field in a precipitation area according to the radial movement speed of precipitation particles caused by a wind field, in combination with radar observation geometry and a three-dimensional wind field inversion algorithm.

[0180] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method for synchronous inversion of Doppler precipitation radar precipitation and three-dimensional wind field, comprising: Step 1) determining the reflectivity factor of the observation area through the echo power of the Doppler precipitation radar; Step 2) determining the precipitation area and calculating the precipitation particle size according to the reflectivity factor; Step 3) calculating the vertical falling speed of the precipitation particles according to the size of the precipitation particles; Step 4) Calculate the radial velocity of precipitation particles according to the echo phase of the Doppler precipitation radar; remove the vertical falling velocity of precipitation particles to obtain the radial motion velocity of precipitation particles caused by the wind field; Step 5) According to the radial motion speed of precipitation particles caused by the wind field, combined with the radar observation geometry and the three-dimensional wind field inversion algorithm, the three-dimensional wind field of the precipitation area is inverted.

2. The method for synchronous inversion of Doppler precipitation radar precipitation and three-dimensional wind field according to claim 1, characterized in that: The Doppler precipitation radar is a satellite-borne or airborne radar, which adopts a working mode of multiple pulse repetition frequencies to expand the radial velocity range that can be measured, and adopts a conical scanning system.

3. The method for synchronous inversion of Doppler precipitation radar precipitation and three-dimensional wind field according to claim 1, characterized in that: The step 1) observes the reflectivity factor Z of the area m for: Where r is the distance from the observation area to the radar, λ is the wavelength of the electromagnetic wave, |K| is the dielectric constant, G at is the transmitting antenna gain, G ar is the receiving antenna gain, θ 0a is the cross-track beamwidth, θ 0c is the beam width along the track, c is the speed of light, τ is the transmit pulse width, P t is the transmission power, P r is the received power.

4. The method for synchronous inversion of Doppler precipitation radar precipitation and three-dimensional wind field according to claim 3 is characterized in that: The step 2) comprises: According to the reflectivity factor Z of the observation area m , the precipitation intensity I is determined by the empirical relationship between radar reflectivity factor and precipitation intensity: FROM m =200I 1.6 According to the precipitation intensity I, the attenuation parameter Λ is determined as: L=4.11I -0.21 The distribution N(D) describing the diameter D of raindrop particles is determined by the attenuation parameter Λ and the normalized number concentration constant N0: N(D)=N0e -ΛD Determination of the average particle size D by numerical integration mean for:

5. The method for synchronous inversion of Doppler precipitation radar precipitation and three-dimensional wind field according to claim 4, characterized in that: The vertical falling velocity v(D) of the precipitation particles in step 3) is: v(D)=1300D mean 0.5 Among them, D mean is the average particle size of the particles.

6. The method for synchronous inversion of Doppler precipitation radar precipitation and three-dimensional wind field according to claim 5, characterized in that: The calculation process of the echo phase of the Doppler precipitation radar in step 4) includes: For the signal transmitted by the Doppler radar, the baseband echo s(t) obtained after down-conversion by the receiver is: s(t)=exp(-j2π[f c τ-0.5α(t-τ) 2 ]) α=W / T p Among them, f c is the carrier frequency, t is the echo time within the pulse, τ is the echo time shift, α is the frequency modulation slope, T p is the pulse width, W is the signal bandwidth; j represents the imaginary part; Construct the reference function s for matched filtering ref (t) is: s ref (t)=exp(-j2π[f c τ0-0.5α(t-τ0) 2 ]) Where τ0 is the reference signal time shift; The pulse compression signal s is obtained by Fourier transform out for: s out =IFFT{FFT[s(t)]·conj[FFT[s ref (t)]]} Among them, FFT is Fourier transform, IFFT is inverse Fourier transform, and conj means finding the conjugate of a complex number; Take two adjacent pulse compression signals A = s out1 , B=s out2 , N is the number of related points, then the correlation coefficient ρ(A, B) of adjacent pulse compression signals is: Among them, μ A , μ B and σ A , σ B , are the mean and standard deviation of A and B respectively; Take the phase of ρ(A,B) This is the echo phase.

7. The method for synchronous inversion of Doppler precipitation radar precipitation and three-dimensional wind field according to claim 6, characterized in that: In step 4), the radial velocity V of the precipitation particles target The calculation process includes: According to the phase of the two pulse repetition frequencies The corresponding radial velocities after folding are: V1 = Among them, V u1 , V u2 are the maximum unambiguous velocity under the corresponding pulse repetition interval, V1+MV u1 =V2+MV u2 =V, M is the number of folds, V is the true speed, let Then the true speed V after unfolding is: in, is the maximum unambiguous speed after expansion: For the maximum unambiguous velocity after double PRF expansion calculated at each observation attitude, n1 and n2 that make the equation valid are calculated according to the following formula: According to n1 and n2, calculate the unfolded radial velocity V corresponding to each single pulse repetition interval. 1True , V 2True : In 1True =V1+2n1V u1 <h2 style=";text-align:left;direction:ltr">V<h2 style=";text-align:left;direction:ltr"> 2True <h2 style=";text-align:left;direction:ltr"> =V2+2n2V<h2 style=";text-align:left;direction:ltr"> u2 The radial velocity V is calculated according to the following formula True : The projection V of the moving platform where the radar is located in the observation direction is obtained according to the following formula: platform_proj : V platform_proj =V platform ·V observe Among them, V platform It is the representation of platform motion in the geographic coordinate system, which consists of the speeds in three directions: V platform =(V north ,V east ,V up ) Among them, V north is the northward velocity of the platform, V east is the eastward speed of the platform, V up is the upward speed of the platform; V observe is the radar observation vector: in, is the angle between the radar observation direction and the positive direction of the z-axis; θ is the angle between the projection of the radar observation direction on the xy plane and the positive direction of the x-axis; The radial velocity V of precipitation particles can be obtained according to the following formula: target : V target =V True -V platform_proj 。 8. The method for synchronous inversion of Doppler precipitation radar precipitation and three-dimensional wind field according to claim 7, characterized in that: The radial motion velocity V of precipitation particles caused by the wind field in step 4) wind for:

9. The method for synchronous inversion of Doppler precipitation radar precipitation and three-dimensional wind field according to claim 8, characterized in that: The three-dimensional wind field in the precipitation area in step 5) is: Among them, V x , V y , V z are the speeds of the three-dimensional atmospheric wind field in the x, y, and z directions respectively, p′ represents the transposed matrix of the observation matrix p, in, With θ n are the elevation and azimuth angles corresponding to the nth observation of the target area, n>3.

10. A Doppler precipitation radar precipitation and three-dimensional wind field synchronous inversion system, characterized in that: include: A reflectivity factor calculation module is used to determine the reflectivity factor of the observation area through the echo power of the Doppler precipitation radar; A precipitation particle size calculation module is used to determine the precipitation area and calculate the precipitation particle size according to the reflectivity factor; A vertical falling speed calculation module is used to calculate the vertical falling speed of precipitation particles according to the size of precipitation particles; The radial motion velocity calculation module is used to calculate the radial velocity of precipitation particles according to the echo phase of the Doppler precipitation radar; remove the vertical falling velocity of precipitation particles to obtain the radial motion velocity of precipitation particles caused by the wind field; and The inversion module is used to invert the three-dimensional wind field in the precipitation area according to the radial motion speed of precipitation particles caused by the wind field, combined with radar observation geometry and three-dimensional wind field inversion algorithm.

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