Search

CN-121613460-B - Radar precipitation measurement method and device based on inclined 45-degree depolarization ratio

CN121613460BCN 121613460 BCN121613460 BCN 121613460BCN-121613460-B

Abstract

The invention provides a radar precipitation measurement method and device based on an inclined 45-degree depolarization ratio, which uses or reforms a radar for realizing inclined 45-degree polarization to acquire single-shot double-receiving two-channel complex voltage data and calculates an inclined baseline depolarization ratio And reflectivity factor Z, identifying melting layer according to vertical directional profile observation collected by the radar in vertical directional mode, and applying upper and lower boundaries of the melting layer to near horizontal scanning mode to implement liquid rainfall identification Perform rain attenuation correction with Z, based on the corrected rain attenuation And Z, inverting rainfall parameters such as rainfall intensity, mass weighted average diameter, normalized intercept, number concentration, water content and the like through a lookup table or a neural network. The invention improves the precision and the robustness of precipitation measurement.

Inventors

  • HUANG HAO
  • LU CHEN
  • ZHAO WENXUAN
  • ZHAO KUN
  • WANG XING

Assignees

  • 南京大学

Dates

Publication Date
20260508
Application Date
20260202

Claims (8)

  1. 1. The radar precipitation measurement method based on the inclined 45-degree depolarization ratio is characterized by comprising the following steps of: calculating the oblique baseline linear depolarization ratio by utilizing two-channel complex voltage data acquired by radar The radar adopts a 45-degree inclined linear polarization single-shot double-shot mode; identifying upper and lower boundaries of a melting layer according to a vertical directional section acquired by the radar in a vertical directional mode, mapping the lower boundaries of the melting layer to radar horizontal scanning mode observation, and then identifying liquid rainfall and shielding mixed phase or ice phase rainfall; for the oblique baseline depolarization ratio And the reflectivity factor Z is used for correcting rain fade; According to the inclined baseline depolarization ratio after correcting rain failure Inversion is carried out on the reflectivity factor Z, and rainfall parameters are obtained, wherein the rainfall parameters comprise rainfall intensity, mass weighted average diameter, normalized intercept, digital concentration and water content; identifying a melting layer according to a vertical directional profile acquired by the radar in a vertical directional mode, wherein the method comprises the following steps: in each vertical directional section, calculating a reflectivity factor Z profile and an inclined 45-degree linear depolarization ratio SLDR profile which are changed along with the height; estimating the center of a zero-degree bright layer according to local peaks in the reflectivity factor Z profile; Determining the upper and lower boundaries of the melting layer according to the height interval corresponding to the inclined 45-degree depolarization ratio SLDR profile; mapping to radar horizontal scanning mode observation according to the height and upper and lower boundaries of the melting layer, identifying liquid rainfall, shielding mixed phase or ice phase rainfall, and carrying out quantitative inversion only on a liquid rainfall area; for the oblique baseline depolarization ratio And the reflectance factor Z is used for correcting rain attenuation, and the method comprises the following steps: for the device with the phase measurement function, the differential propagation phase shift is calculated after the phase shift is compounded from the inclined 45-degree substrate back to the H/V substrate through substrate transformation And differential propagation phase shift rate ; Using the differential propagation phase shift rate Empirical relationship to specific decay or self-consistent algorithm for the oblique baseline depolarization ratio And the reflectivity factor Z is used for correcting rain fade; For devices without phase measurement function, a device based on a reflectivity factor Z and a tilted baseline depolarization ratio is adopted Self-consistent rain fade correction method with optimal radial consistency, and method for correcting inclined baseline depolarization ratio And the reflectivity factor Z is used for correcting rain fade.
  2. 2. The radar precipitation measurement method based on the inclined 45-degree depolarization ratio according to claim 1, wherein the inclined baseline depolarization ratio is calculated according to two-channel complex voltage data acquired by the radar And a reflectance factor Z, further comprising: When the radar cannot scan horizontally, a pitching and azimuth mechanism is additionally arranged on the radar, or a scanning function is started to realize near-horizontal scanning; when the radar polarization mode is horizontal/vertical polarization, the transmitting linear polarization direction is rotated by 45 degrees in a plane vertical to the beam propagation direction so as to realize oblique 45-degree linear polarization transmission; The radar maintains a two-channel coherent receiving structure, and a vertical pointing mode is reserved for identifying a melting layer.
  3. 3. The radar precipitation measurement method based on the inclined 45-degree depolarization ratio according to claim 1, wherein the inclined baseline depolarization ratio is calculated by using two-channel complex voltage data acquired by a radar And a reflectance factor Z comprising: decoupling two-channel complex voltage data acquired by the radar; calculating co-polarized power and cross-polarized power between the decoupled two-channel complex voltage data; Calculating the inclined baseline depolarization ratio according to the ratio of the co-polarized power and the cross-polarized power after noise depolarization in the power domain ; After noise depolarization is carried out on the co-polarized power, the reflectance factor Z is obtained through conversion of a radar constant and an observation distance; Noise depolarization and filtering are performed on the oblique baseline linear depolarization ratio SLDR in the region where the signal-to-noise ratio SNR is less than the preset threshold.
  4. 4. The radar precipitation measurement method based on a diagonal 45-degree depolarization ratio according to claim 1, wherein the diagonal baseline depolarization ratio after correction for rain failure And a reflectivity factor Z, resulting in precipitation parameters, comprising: oblique baseline linear depolarization ratio after correcting rain attenuation based on lookup table LUT or multilayer perceptron MLP neural network And inverting the reflectivity factor Z to obtain precipitation parameters.
  5. 5. The method for radar precipitation measurement based on a diagonal 45-degree depolarization ratio according to claim 4, wherein the diagonal baseline depolarization ratio after correction for rain failure is based on LUT Inversion is carried out on the reflectivity factor Z to obtain precipitation parameters, and the method comprises the following steps: Construction of oblique baseline linear depolarization ratio based on T-matrix scattering model And a lookup table of the association between the reflectivity factor Z and rainfall intensity, mass weighted average diameter, normalized intercept, number concentration, water content precipitation parameters; For observed oblique baseline linear depolarization ratio And obtaining corresponding precipitation parameters through the lookup table after multidimensional interpolation is carried out on the reflectivity factor Z.
  6. 6. The radar precipitation measurement method based on a diagonal 45-degree depolarization ratio according to claim 4, wherein the diagonal baseline depolarization ratio after correcting for rain failure based on an MLP neural network Inversion is carried out on the reflectivity factor Z to obtain precipitation parameters, and the method comprises the following steps: oblique baseline depolarization ratio after correcting rain failure And taking the reflectivity factor Z as the input of the MLP neural network to obtain the precipitation parameters output by the MLP neural network.
  7. 7. A radar precipitation measurement device based on a 45 degree oblique depolarization ratio, characterized in that it is applied to the radar precipitation measurement method based on a 45 degree oblique depolarization ratio according to any one of claims 1 to 6, and comprises: The calculation module is used for calculating the inclined baseline depolarization ratio according to the two-channel complex voltage data acquired by the radar The radar adopts a 45-degree inclined linear polarization single-shot double-shot mode; The identification module is used for identifying the upper and lower boundaries of the melting layer according to the vertical directional profile acquired by the radar in the vertical directional mode, mapping the lower boundaries of the melting layer to the radar horizontal scanning mode for observation, and then identifying liquid rainfall and shielding mixed phase or ice phase rainfall; a correction module for correcting the oblique baseline depolarization ratio And the reflectivity factor Z is used for correcting rain fade; An inversion module for correcting the inclined baseline depolarization ratio according to the rain failure And inverting the reflectivity factor Z to obtain precipitation parameters, wherein the precipitation parameters comprise rainfall intensity, mass weighted average diameter, normalized intercept, digital concentration and water content.
  8. 8. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the radar precipitation measurement method based on a 45 degree oblique depolarization ratio as claimed in any one of claims 1 to 6 when the program is executed by the processor.

Description

Radar precipitation measurement method and device based on inclined 45-degree depolarization ratio Technical Field The invention relates to the technical field of weather forecast, in particular to a radar precipitation measurement method and device based on an inclined 45-degree depolarization ratio. Background Radar Quantitative Precipitation Estimation (QPE) is one of the key technologies in weather forecast, urban waterlogging prevention and watershed hydrologic early warning. Traditional single polarization weather radar can only acquire reflectivity factorsThe accurate acquisition of micro-physical information such as the size, the shape and the like of precipitation is difficult, and accurate observation of precipitation is difficult. In order to improve the microphysical observation and quantitative precipitation estimation capability of cloud precipitation, the double-polarization radar technology is widely developed. For example, the weather radar can measure the echo and the phase through the dual-transmitting dual-receiving system on the horizontal and vertical two orthogonal polarization channels, and not only can obtain the reflectivity factorIt is also possible to obtain differential reflectivity sensitive to particle phase, particle size, size/shape, and moisture contentDifferential phase(Specific differential propagation phase)) Correlation coefficientAnd a series of polarization variables are equal, so that the quantitative inversion precision of the precipitation parameters is improved. In addition, the dual polarization technology is also used for cloud radar, and the existing cloud radar generally directs an antenna beam to be near to the vertical direction, adopts a single-shot dual-reception system (such as MIRA-35C), and arranges two mutually orthogonal linear polarization channels (which can be still be conventionally recorded as "horizontal" H and "vertical" V, but are all on the horizontal plane at the moment) in a plane perpendicular to the propagation direction. The receiving end can output the polarization power, the cross polarization power and the phase information of the two channels at the same time, thereby constructing Doppler spectrum and reflectivity factors on the vertical profileAnd linear depolarization ratio. When the rain drops are vertically oriented, the average long axis of the rain drops is horizontal, the propagation direction is vertical, the scattering characteristics of the two orthogonal linear polarizations on the horizontal plane are approximately equivalent to those of the liquid rain drops, H/V-In pure rain areas, which are usually very low, the melting layer (bright band) and the solid precipitation area will be significantly raised. Thus, the prior cloud radar mostly utilizes vertical pointingThe height and thickness of the melting layer are identified, and the melting layer is used for cloud physical research or assisting in identifying a bright band of a weather radar, so that stable constraint is difficult to provide for precipitation parameters (particularly particle size). Notably, also because of the vertical downward pointing, the scattered power and phase of two orthogonal linear polarizations of the hydrogel particles are approximately equal, and cloud radar does not generally adopt a dual-transmission dual-reception system #The true value is close to 0 dB,The true value is near 0 deg/km). In recent years, in order to further improve the application field of the cloud radar, the industry has begun to try to use the cloud radar of the single-shot dual-reception system for horizontal PPI scanning or RHI scanning. In the early stage, the radar mainly uses the conventional weather radar to adopt horizontal and vertical polarization channels, however, unlike the conventional weather radar, the single-transmission double-reception polarization parameters are as followsAlthough it may be used to indicate melting particles, tilting ice crystal particles. In the case of a rainfall,Only larger (flatter) oscillations of the raindrops (having flatter shape sums) can be represented, but the quantitative description ability for rainfall information is insufficient. To increase sensitivity to particle shape, some research efforts have proposed measuring the oblique baseline linear depolarization ratio SLDR under a "45 degree oblique linear polarization" substrate. For example, one study on 35 GHz MIRA-35 cloud radar suggests that by operating the radar in SLDR mode, the distribution of particle shapes in the vertical direction in the mix Xiang Yun can be inverted using the sensitivity of SLDR to particle geometry measured by scanning. Scholars also try to identify different ice crystal habits (e.g., dendrites, columns, shot, hail, etc.) using the observations of scanning polarized W-band radar in SLDR modes, demonstrating that SLDR mode has important application potential in cloud/ice microphysical inversion. The above work still focuses mainly on cloud an