CN103616736A - Rainfall foundation monitoring method based on GNSS signal depolarization effect - Google Patents

本发明公开了一种基于GNSS信号去极化效应的降雨强度地基监测方法。利用穿过雨区后的GNSS前向散射信号中的水平极化和垂直极化分量，结合当地的雨滴谱分布特性，计算描述GNSS信号去极化效应的交叉极化分辨率XPD与降雨强度R的关系；根据该XPD-R关系模型，利用GNSS接收机测量的交叉极化分辨率（XPD）值，得到降雨强度。本发明对于下一步开展相关的外场实验，拓展GNSS的气象应用，实时估测降雨强度，实现全球降雨观测具有重要的参考价值；对于发挥GNSS的特有优势，发展对地遥感技术，探索区域降水探测新技术具有重要意义。

The invention discloses a ground monitoring method for rainfall intensity based on the depolarization effect of GNSS signals. Using the horizontal and vertical polarization components of the GNSS forward scattering signal after passing through the rain area, combined with the local raindrop spectral distribution characteristics, the cross-polarization resolution XPD and rainfall intensity R that describe the depolarization effect of the GNSS signal are calculated According to the XPD-R relationship model, the rainfall intensity is obtained by using the cross-polarization resolution (XPD) value measured by the GNSS receiver. The present invention has important reference value for carrying out related field experiments in the next step, expanding the meteorological application of GNSS, estimating the rainfall intensity in real time, and realizing global rainfall observation; for developing the unique advantages of GNSS, developing ground remote sensing technology, and exploring regional precipitation detection New technologies are important.

Rainfall intensity groundwork detection method based on GNSS depolarization signal effect

Technical field

The invention belongs to atmospheric remote sensing and atmospheric exploration technical field, is a kind of method of rainfall to the depolarisation effect inverting rainfall intensity of vacant lot link GNSS signal generation of utilizing.

Background technology

Traditionally, people use rain gage directly to obtain single-point rainfall intensity.It is high that rain gage is surveyed rainfall survey station single-point precision, and its measurement result is the master data source of carrying out regional analysis.But due to the sparse property of its laying, the unevenness of distribution, make rain gage observation Shortcomings aspect extensive area Rainfall Monitoring.In recent years, utilize the parameter such as reflectivity (Z), difference propagation phase-shift (KDP), Analysis of Differential Reflectivity Factor Measured (ZDP) of ground weather radar and the relation of rainfall intensity (R), quantitatively calculating the rainfall intensity in radius of investigation, is the more method of research.But weather radar is active remote sensing equipment, disguised not enough.Utilizing satellite-borne microwave imager and precipitation radar (TRMM/PR) remote sensing satellite track below rainfall intensity is also one of focus in recent years.But its spatial resolution and temporal resolution are limited.

As everyone knows, rainfall has serious impact to communication system.Rainfall, to the decay of microwave and depolarisation effect, is the factor can not be ignored in communication, for no exception in the communication system of Ku, K, Ka wave band.The research of TAUR (1975) and Ali (1986) shows, the proportional relation of rainfall attenuation and rainfall intensity.Heavy showers can produce stronger decay, and decay increases along with the increase of microwave frequency.The adverse effect of rainfall attenuation to communication, can be used as the information source of monitoring rainfall.The power attenuation of people based on existing wireless communications network signal and the relations of rainfall intensity such as Israel Messer (2006), studied the method for Regional Precipitation intensity monitoring.Goldshtein and Messer (2009) have utilized the rainfall attenuation of International Telecommunications Union (ITU) (ITU) suggestion and the empirical model of rainfall intensity, have estimated the average rainfall intensity on signal path when microwave frequency is 20GHz.Yellow (2006) researcher of Lee utilizes the rainfall attenuation of Ku band communication satellite to carry out technical research and experimental verification to the rainfall intensity on signal path; The obtaining means of rainfall intensity has been enriched in the research of this technology, for the regionally detecting of rainfall intensity provides valuable data.The people such as E.Cardellach in 2010 have proposed to utilize the concept of the GNSS polarization occultation acquisition of signal heavy showers that low orbit satellite receives, but in the document of publishing, have no so far concrete theoretical research and experimental result.

Summary of the invention

The object of the invention is to propose the rainfall intensity groundwork detection method based on GNSS signal, provide a kind of real-time, continuous, passive and monitor the Ground-based remote sensing detection method of rainfall intensity on a large scale, for disastrous rainfall monitoring early warning, Climate assessed are explored new approach and means, for the Big Dipper two generations satellite navigation system of expanding China's independent development capability provides technical support in the application such as rainfall monitoring on a large scale of space-based, ground and surface ship off-lying sea.

The technical solution that realizes the object of the invention is:

General thought of the present invention is: utilize through the horizontal polarization in the GNSS Forward scattering signal behind rain belt and vertical polarization component, in conjunction with local raindrop size distribution distribution character, calculate the cross polarization resolution XPD of GNSS depolarization signal effect and the relation of rainfall intensity R described; According to this XPD-R relational model, cross polarization resolution (XPD) value of utilizing GNSS receiver to measure, obtains rainfall intensity.

According to above-mentioned general thought, the present invention is as follows to the implementation procedure based on GNSS depolarization signal effect monitoring rainfall intensity:

1, according to actual raindrop shape approximation model, adopt Rayleigh approximation elliposoidal particle scattering algorithm, calculate the forward scattering amplitude f of horizontal direction after the single raindrop that GNSS signal incides different radii _hforward scattering amplitude f with vertical direction _v;

2, the GNSS signal obtaining according to step 1 incides the forward scattering amplitude f of horizontal direction after the single raindrop of different radii _hforward scattering amplitude f with vertical direction _v, utilize raindrop size distribution distributed model, calculate the propagation constant k of GNSS signal horizontal direction after group's raindrop _hpropagation constant k with vertical direction _v;

The propagation constant k of GNSS signal horizontal direction after group's raindrop of 3, obtaining according to step 2 _hpropagation constant k with vertical direction _v, adopt method for numerical simulation, obtain the XPD-R relational model of cross polarization resolution (XPD) with the rainfall intensity (R) of describing GNSS depolarization signal effect;

4, cross polarization resolution (XPD) value of utilizing GNSS polarized signal receiver to measure, the XPD-R relational model obtaining according to step 3, obtains rainfall intensity.

The present invention compared with prior art, its remarkable advantage:

(1) passive passive detection: because signal source is GNSS signal, without emitter, equipment complexity and cost are low;

(2) real-time, continuity are strong: because GNSS receiver sample frequency is higher, can realize rainfall intensity in real time, continuous monitoring, therefore, the temporal resolution of Rainfall measurement is higher;

(3) GNSS signal resource is abundant, covering the whole world, can realize the rainfall of unattended high mountain, desert area and measure, and boat-carrying, on-board equipment can be realized the motor-driven monitoring of marine rainfall;

(4) disguise: owing to taking passive detection pattern to be difficult for being found, effective ego-defense.

Accompanying drawing explanation

Fig. 1 is the rainfall intensity groundwork detection method realization flow figure based on GNSS depolarization signal effect of the present invention.

Fig. 2 is in the path situation of different rain belts, and GPS L1 frequency band signals is the situation of change with rainfall intensity (R) through the cross polarization resolution (XPD) after rain belt.

Fig. 3 is in the path situation of different rain belts, and GPS L2 frequency band signals is the situation of change with rainfall intensity (R) through the cross polarization resolution (XPD) after rain belt.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail.

The first step, utilizes Ray formula [Oguchi, T., Electromagnetic Wave Propagation and Scattering in Rain and Other Hydrometeors, Proc. IEEE, 1983,71:1029-1079], the relative complex permittivity of calculating raindrop; According to actual raindrop shape approximation model, adopt Rayleigh approximation elliposoidal particle scattering algorithm, calculate the forward scattering amplitude f of horizontal direction after the single raindrop that this GNSS signal incides different radii _hforward scattering amplitude f with vertical direction _v.

Ray formula used is

ϵ ' = ϵ ∞ + ( ϵ s - ϵ ∞ ) [ 1 + ( λ s λ ) 1 - α sin ( απ 2 ) ] 1 + 2 ( λ s λ ) 1 - α sin ( απ 2 ) + ( λ s λ ) 2 ( 1 - α ) - - - ( 1 )

ϵ ' ' = ( ϵ s - ϵ ∞ ) ( λ s λ ) 1 - α cos ( απ 2 ) 1 + 2 ( λ s λ ) 1 - α sin ( απ 2 ) + ( λ s λ ) 2 ( 1 - α ) + σλ 18.8496 × 10 10 - - - ( 2 )

Parameter is wherein

σ＝12.5664×10 ⁸

ε _∞＝5.27134+2.16474×10 ^-2t-1.31198×10 ^-3t ²

α = 16.8129 t + 273 + 6.09265 × 10 - 2

In above-mentioned formula, λ is operation wavelength (cm), t be temperature (℃), this formula scope of application is the temperature of-20 ℃ to 50 ℃.

Actual raindrop shape approximation model is,

a b =

1 r eq &le; 0.5 1.0048 + 0.0114 * r eq 10 - 10.512 * ( r eq 10 ) 2 + 29.456 * ( r eq 10 ) 3 - 26.832 * ( r eq 10 ) 4 0.5 < r eq &le; 4.5 - - - ( 1 )

Wherein, a is raindrop minor semi-axis (cm), and b is raindrop major semi-axis (cm), r _eqbe and the isopyknic spheroid equivalent redius of actual raindrop (cm).

Scattering algorithm formula used is

f h = k 2 a b 2 3 &epsiv; - 1 1 + ( &epsiv; - 1 ) A 1 - - - ( 2 )

f v = k 2 a b 2 3 [ &epsiv; - 1 1 + ( &epsiv; - 1 ) A 1 cos 2 &alpha; + &epsiv; - 1 1 + ( &epsiv; - 1 ) A 2 sin 2 &alpha; ] - - - ( 3 )

Parameter is wherein

m = b a

A 1 = 1 2 ( m 2 - 1 ) ( m 2 m 2 - 1 tan - 1 m 2 - 1 - 1 )

A ₂＝1-2A ₁

In above-mentioned formula, a is raindrop minor semi-axiss, and b is raindrop major semi-axis, and k is free-space propagation constant, and α is incident angle.

Second step, the GNSS signal obtaining according to step 1 incides the forward scattering amplitude f of horizontal direction after the single raindrop of different radii _hforward scattering amplitude f with vertical direction _v, utilize raindrop size distribution to distribute scattering amplitude is superposeed, obtain the forward scattering polarization characteristic of group raindrop to microwave, utilize formula

k h , v = 2 &pi; k &Integral; f h , v ( r eq , 0 ) n ( r eq ) d r eq - - - ( 4 )

Draw the propagation constant k of GNSS signal horizontal direction after group's raindrop _hpropagation constant k with vertical direction _v.

In formula, n (r _eq) for raindrop size distribution distributes, k is free-space propagation constant, f _hand f _vit is respectively the forward scattering amplitude of the horizontal and vertical direction of single raindrop.

MP raindrop size distribution distributes:

N(r)=N ₀exp(-Λr) (5)-

Wherein, the equivalent redius that r is raindrop (mm), N ₀be respectively concentration with Λ and scale parameter has

N ₀=16000(m ^-3mm ^-1),Λ=8.2R ^-0.21

Wherein, R is raininess (mm h ^-1).The raindrop number of raindrop radius between r～r+dr in N (r) dr representation unit volume.MP spectrum distributes and has the feature of general raindrop size distribution, applies comparatively extensive.

The 3rd step, the propagation constant k of GNSS signal horizontal direction after group's raindrop of obtaining according to step 2 _hpropagation constant k with vertical direction _v, adopt method for numerical simulation, obtain the XPD-R relational model of cross polarization resolution (XPD) with the rainfall intensity (R) of describing GNSS depolarization signal effect.

The depolarisation effect of rainfall to microwave, uses cross polarization resolution (XPD) tolerance conventionally, and it is defined as

XPD = 20 lg | E 11 E 12 | - - - ( 6 )

Wherein, E ₁₁for same polarization electric field intensity, E ₁₂for cross polarization electric field intensity.Gps signal for right-handed circular polarization, E ₁₁for right-handed circular polarization signal, E ₁₂for left-hand circular polarization signal.

The cross polarization resolution XPD of right-handed circular polarization signal can calculate by following formula:

XPD = 20 lg | ( 1 + G ) e 2 &phi;i 1 - G | - - - ( 7 )

Wherein,

G = e ( &lambda; 1 - &lambda; 2 ) L , - - - ( 8 )

L is the path that signal passes rain belt.Suppose raindrop inclination angle Gaussian distributed, average is θ ₀, standard deviation is σ _θ.φ is the amount relevant with raindrop inclination angle, when raindrop change of pitch angle Gaussian distributed, and φ=θ ₀, and

&lambda; 1 - &lambda; 2 = - i ( k h - k v ) e - 2 &sigma; &theta; 2 2 . - - - ( 9 )

Utilize the above-mentioned propagation constant k trying to achieve _hand k _v, in conjunction with MP raindrop size distribution, distribute, can set up XPD-R relational model.

The 4th step, cross polarization resolution (XPD) value of utilizing GNSS polarized signal receiver to measure, the XPD-R relational model obtaining according to step 3, obtains rainfall intensity.Select the GNSS polarized signal receiver that meets following requirement to measure:

Frequency: GPS L1 frequency range 1575.42 ± 1.023MHz

Carrier phase measurement precision :≤1mm

Antenna peak gain: >=10dB

Antenna polarization requires: left-handed and dextrorotation output

Output observed quantity turnover rate: >=1Hz.

Below in conjunction with embodiment, the present invention is described in further details.

Embodiment

The GPS L1 frequency band signals (frequency is 1575.42MHz) of choosing right-handed circular polarization is analyzed for example.

1, calculate forward scattering amplitude

Choosing the GPS L1 frequency band signals through behind rain belt that GNSS receiver can collect calculates; While supposing rainfall, raindrop temperature is 20 ℃, utilizes Ray formula to calculate the now relative complex permittivity of raindrop.According to actual raindrop shape approximation model, adopt Rayleigh approximation elliposoidal particle scattering algorithm, the gps signal that calculates this frequency incides the forward scattering amplitude f of horizontal direction after the single raindrop of different particle radii _hforward scattering amplitude f with vertical direction _v.

2, calculate propagation constant

The GPS L1 frequency band signals obtaining according to step 1 incides the forward scattering amplitude f of horizontal direction after single raindrop _hforward scattering amplitude f with vertical direction _v, utilize raindrop size distribution to distribute scattering amplitude is superposeed, obtain the forward scattering polarization characteristic of group raindrop to microwave, utilize formula (3) to draw the propagation constant k of GPS L1 frequency band signals horizontal direction after group's raindrop _hpropagation constant k with vertical direction _v.MP spectrum distributes as shown in formula (4), (5).

3, XPD-R relational model

The propagation constant k of GPS L1 frequency band signals horizontal direction after group's raindrop of obtaining according to step 2 _hpropagation constant k with vertical direction _v, adopt method for numerical simulation, obtain the XPD-R relational model of cross polarization resolution (XPD) with the rainfall intensity (R) of describing GPS L1 frequency band signals depolarisation effect.The gps satellite elevation angle is that the gps satellite of 0 degree calculates, because depolarisation effect is now [Cardellach comparatively obviously, E., A.Rius, and F.Cerezo, Polarimetric GNSS Radio-Occultations for heavy rain detection, Geoscience and Remote Sensing Symposium, 2010,3841-3844].Here rainfall intensity scope is 1-100mm h ^-1, rain belt path is elected respectively 1km, 5km, 10km and 50km as, suppose raindrop be subject to aerodynamic affect less, its inclination angle Gaussian distributed, average is 0 °, standard deviation is 0 °.According to formula (7), (8), (9), can obtain in the path situation of different rain belts, cross polarization resolution (XPD) is with the situation of change of rainfall intensity (R), as shown in Figure 2.

As shown in Figure 2, under specific frequency, specific rain belt path, the XPD of GPS L1 frequency band signals behind rain belt is along with the increase of rainfall intensity reduces gradually.This is due to the increase along with rainfall intensity, and the scattering that raindrop produce signal is stronger, and the cross polarization amount of generation is stronger, thereby a little less than making co polarized component, finally makes XPD reduce gradually.When the path of different rain belts, path is longer, and the value of XPD is less, tallies with the actual situation.To sum up, when the path of different rain belts, cross polarization resolution is all responsive to rainfall intensity, and XPD-R relation has feasibility and the practicality of inverting rainfall intensity.

Similarly, can obtain other frequency band signals of GNSS through after rain belt, cross polarization resolution (XPD) is with the situation of change of rainfall intensity (R).The XPD-R relation of GPS L2 frequency band signals (frequency is 1227.60MHz) as shown in Figure 3.

4, obtain rainfall intensity

According to this XPD-R relational model, cross polarization resolution (XPD) value of utilizing GNSS receiver to measure, obtains rainfall intensity.

1.一种基于GNSS信号去极化效应的降雨强度地基监测方法，其特征在于步骤如下：1. a kind of rainfall intensity foundation monitoring method based on GNSS signal depolarization effect, it is characterized in that step is as follows: 步骤1，利用Ray公式，计算雨滴的相对复介电常数，根据实际雨滴形状近似模型，采用瑞利近似椭球形粒子散射算法，计算GNSS信号入射到不同半径的单一雨滴后水平方向的前向散射振幅f_h和垂直方向的前向散射振幅f_v；Step 1, using the Ray formula to calculate the relative complex permittivity of raindrops, according to the actual raindrop shape approximation model, using the Rayleigh approximate ellipsoidal particle scattering algorithm, calculate the forward scattering in the horizontal direction after the GNSS signal is incident on a single raindrop with different radii amplitude f _h and forward scattering amplitude f _v in the vertical direction; 步骤2，根据步骤1所获取的GNSS信号入射到不同半径的单一雨滴后水平方向的前向散射振幅f_h和垂直方向的前向散射振幅f_v，利用雨滴谱分布，计算GNSS信号经过群雨滴后水平方向的传播常数k_h和垂直方向的传播常数k_v；Step 2, according to the forward scattering amplitude f _h in the horizontal direction and the forward scattering amplitude f _v in the vertical direction after the GNSS signal acquired in step 1 is incident on a single raindrop with different radii, use the spectral distribution of raindrops to calculate the GNSS signal passing through a group of raindrops Then the propagation constant k _h in the horizontal direction and the propagation constant k _v in the vertical direction; 步骤3，根据步骤2所获取的GNSS信号经过群雨滴后水平方向的传播常数k_h和垂直方向的传播常数k_v，采用数值模拟，获取描述GNSS信号去极化效应的交叉极化分辨率XPD与降雨强度R的XPD-R关系模型；Step 3, according to the propagation constant k _h in the horizontal direction and the propagation constant k _v in the vertical direction of the GNSS signal obtained in step 2 after passing through the group of raindrops, use numerical simulation to obtain the cross-polarization resolution XPD describing the depolarization effect of the GNSS signal XPD-R relationship model with rainfall intensity R; 步骤4，利用GNSS极化信号接收机测量的交叉极化分辨率XPD值，根据步骤3获取的交叉极化分辨率XPD与降雨强度R的XPD-R关系，得到降雨强度。Step 4, using the cross-polarization resolution XPD value measured by the GNSS polarimetric signal receiver, and according to the XPD-R relationship between the cross-polarization resolution XPD obtained in step 3 and the rainfall intensity R, the rainfall intensity is obtained. 2.根据权利要求1所述的基于GNSS信号去极化效应的降雨强度地基监测方法，其特征在于：所述步骤1中，所用Ray公式为2. the rainfall intensity ground monitoring method based on GNSS signal depolarization effect according to claim 1, is characterized in that: in described step 1, used Ray formula is &epsiv;&epsiv; '' == &epsiv;&epsiv; &infin;&infin; ++ (( &epsiv;&epsiv; sthe s -- &epsiv;&epsiv; &infin;&infin; )) [[ 11 ++ (( &lambda;&lambda; sthe s &lambda;&lambda; )) 11 -- &alpha;&alpha; sinsin (( &alpha;&pi;&alpha;&pi; 22 )) ]] 11 ++ 22 (( &lambda;&lambda; sthe s &lambda;&lambda; )) 11 -- &alpha;&alpha; sinsin (( &alpha;&pi;&alpha;&pi; 22 )) ++ (( &lambda;&lambda; sthe s &lambda;&lambda; )) 22 (( 11 -- &alpha;&alpha; )) &epsiv;&epsiv; '' '' == (( &epsiv;&epsiv; sthe s -- &epsiv;&epsiv; &infin;&infin; )) (( &lambda;&lambda; sthe s &lambda;&lambda; )) 11 -- &alpha;&alpha; coscos (( &alpha;&pi;&alpha;&pi; 22 )) 11 ++ 22 (( &lambda;&lambda; sthe s &lambda;&lambda; )) 11 -- &alpha;&alpha; sinsin (( &alpha;&pi;&alpha;&pi; 22 )) ++ (( &lambda;&lambda; sthe s &lambda;&lambda; )) 22 (( 11 -- &alpha;&alpha; )) ++ &sigma;&lambda;&sigma;&lambda; 18.849618.8496 &times;&times; 1010 1010 其中in σ＝12.5664×10⁸ σ=12.5664×10 ⁸

ε_∞＝5.27134+2.16474×10^-2t-1.31198×10^-3t² ε _∞ =5.27134+2.16474×10 ^-2 t-1.31198×10 ^-3 t ² &alpha;&alpha; == 16.812916.8129 tt ++ 273273 ++ 6.092656.09265 &times;&times; 1010 -- 22 上述式中λ为工作波长(cm)，t为温度(℃)，该公式适用范围为-20℃到50℃的温度；In the above formula, λ is the working wavelength (cm), t is the temperature (°C), and the applicable range of this formula is from -20°C to 50°C; 实际雨滴形状近似模型为，The approximate model of the actual raindrop shape is, aa bb == 11 rr eqeq &le;&le; 0.50.5 1.00481.0048 ++ 0.01140.0114 ** rr eqeq 1010 -- 10.51210.512 ** (( rr eqeq 1010 )) 22 ++ 29.45629.456 ** (( rr eqeq 1010 )) 33 -- 26.83226.832 ** (( rr eqeq 1010 )) 44 0.50.5 << rr eqeq &le;&le; 4.54.5 其中,a是雨滴短半轴(cm)，b是雨滴长半轴(cm)，r_eq是和实际雨滴等体积的球体等效半径(cm)；Among them, a is the semi-minor axis of the raindrop (cm), b is the semi-major axis of the raindrop (cm), r _eq is the equivalent radius of a sphere (cm) with the same volume as the actual raindrop; 瑞利近似椭球形粒子散射算法公式为The formula of Rayleigh approximate ellipsoidal particle scattering algorithm is mm == bb aa ,, AA 11 == 11 22 (( mm 22 -- 11 )) (( mm 22 mm 22 -- 11 tanthe tan -- 11 mm 22 -- 11 -- 11 )) ,, AA 22 == 11 -- 22 AA 11 ff hh == kk 22 aa bb 22 33 &epsiv;&epsiv; -- 11 11 ++ (( &epsiv;&epsiv; -- 11 )) AA 11 ff vv == kk 22 aa bb 22 33 [[ &epsiv;&epsiv; -- 11 11 ++ (( &epsiv;&epsiv; -- 11 )) AA 11 coscos 22 &alpha;&alpha; ++ &epsiv;&epsiv; -- 11 11 ++ (( &epsiv;&epsiv; -- 11 )) AA 22 sinsin 22 &alpha;&alpha; ]] 其中，a是雨滴短半轴，b是雨滴长半轴，k为自由空间传播常数，α为入射角。Among them, a is the semi-minor axis of the raindrop, b is the semi-major axis of the raindrop, k is the free space propagation constant, and α is the incident angle. 3.根据权利要求1所述的基于GNSS信号去极化效应的降雨强度地基监测方法，其特征在于：所述步骤2中，计算传播常数k_h和k_v的计算公式为3. the rainfall intensity ground-based monitoring method based on GNSS signal depolarization effect according to claim 1, is characterized in that: in the described step 2, the calculation formula of calculating propagation constant _k and _k is: kk hh ,, vv == 22 &pi;&pi; kk &Integral;&Integral; ff hh ,, vv (( rr eqeq ,, 00 )) nno (( rr eqeq )) dd rr eqeq 式中,n(r_eq)为雨滴谱分布,k为自由空间传播常数，f_h和f_v分别是GNSS信号入射到单一雨滴后水平和垂直方向的前向散射振幅；计算中利用MP雨滴谱分布模型，其公式为where n(r _eq ) is the spectral distribution of raindrops, k is the free space propagation constant, f _h and f _v are the horizontal and vertical forward scattering amplitudes of the GNSS signal incident on a single raindrop, respectively; the calculation uses the MP raindrop spectrum The distribution model, whose formula is N(r)=N₀(exp)-(Λr)N(r)=N ₀ (exp)-(Λr) 其中，r为雨滴的等效半径(mm)，N₀和Λ分别为浓度和尺度参数有Among them, r is the equivalent radius of the raindrop (mm), N ₀ and Λ are the concentration and scale parameters respectively. N₀=16000(m^-3mm^-1),Λ=8.2R^-0.21 N ₀ =16000(m ^-3 mm ^-1 ), Λ=8.2R ^-0.21 其中，R为雨强(mm h^-1)，N(r)dr表示单位体积内雨滴半径介于r～r+dr之间的雨滴数目。Wherein, R is the rain intensity (mm h ^-1 ), and N(r)dr represents the number of raindrops whose radius is between r~r+dr in a unit volume. 4.根据权利要求1所述的基于GNSS信号去极化效应的降雨强度地基监测方法，其特征在于：所述步骤3中，数值模拟交叉极化分辨率XPD与降雨强度R的XPD-R关系，所用公式为4. the rainfall intensity ground monitoring method based on GNSS signal depolarization effect according to claim 1, is characterized in that: in described step 3, the XPD-R relation of numerical simulation cross-polarization resolution XPD and rainfall intensity R , the formula used is &lambda;&lambda; 11 -- &lambda;&lambda; 22 == -- ii (( kk hh -- kk vv )) ee -- 22 &sigma;&sigma; &theta;&theta; 22 22 GG == ee (( &lambda;&lambda; 11 -- &lambda;&lambda; 22 )) LL XPDXPD == 2020 lglg || (( 11 ++ GG )) ee 22 &phi;i&phi;i 11 -- GG || 式中L为信号穿过雨区的路径长度，k_h和k_v分别为GNSS信号经过群雨滴后水平方向的传播常数和垂直方向的传播常数，φ是与雨滴倾角有关的量，当雨滴倾角变化服从高斯分布时，等于其均值，σ_θ为雨滴倾角分布的标准差。In the formula, L is the path length of the signal passing through the rain area, k _h and k _v are the propagation constants of the GNSS signal in the horizontal direction and the vertical direction after passing through the group of raindrops, respectively, and φ is a quantity related to the inclination angle of raindrops. When the inclination angle of raindrops When the change obeys the Gaussian distribution, it is equal to its mean value, and σ _θ is the standard deviation of the raindrop inclination angle distribution. 5.根据权利要求1所述的基于GNSS信号去极化效应的降雨强度地基监测方法，其特征在于：所述步骤4中，对GNSS极化信号接收机的技术要求为5. the rainfall intensity ground-based monitoring method based on GNSS signal depolarization effect according to claim 1, is characterized in that: in described step 4, the technical requirement to GNSS polarization signal receiver is 频率：GPS L1频段1575.42±1.023MHzFrequency: GPS L1 frequency band 1575.42±1.023MHz 载波相位测量精度：≤1mmCarrier phase measurement accuracy: ≤1mm 天线峰值增益：≥10dBAntenna peak gain: ≥10dB 天线极化要求：左旋和右旋输出Antenna polarization requirements: left-handed and right-handed output 输出观测量更新率：≥1Hz。Output observation update rate: ≥1Hz.