本文選題：雙偏振雷達 + 衰減訂正　； 參考：《中國民航大學》2017年碩士論文

【摘要】：氣象雷達是探測氣象環(huán)境的重要手段,廣泛應用于減災和災害預警,它根據(jù)回波的變化來評估氣象目標的特性,當路徑上存在降雨區(qū)時,會造成反射率的衰減,無法準確的估計探測目標的氣象特征,也可能淹沒后方降雨區(qū)。對于頻率較低的X波段,這種衰減更加嚴重,為了準確分析氣象目標的真實特性,提高降水估測的精度,需要對反射率進行衰減訂正。雙偏振多普勒雷達相比于常規(guī)雷達,能夠提供表征粒子微物理特性的差分傳播相移,差分傳播相移與降雨率之間不僅具有比較高的相關性,而且還具有不受波束傳播阻礙效應、雷達校準、傳播路徑衰減影響的特性,因此使用差分傳播相移進行反射率的衰減訂正有很大的優(yōu)勢。然而差分傳播相移與差分傳播相移率的估計效果容易受到多變性的氣象環(huán)境和衰減的偏振參量的影響,導致使用差分傳播相移與對降雨區(qū)的反射率進行衰減訂正的性能降低,先驗信息難以獲取也會導致差分傳播相移率的估計能力下降,并且在低信噪比的情況下難以保留真實的氣象信息。針對上述問題,本論文提出的降雨區(qū)反射率衰減訂正方法能夠獲得較好的訂正效果。論文的主要工作為:第一,介紹了雙偏振多普勒雷達的工作原理以及主要的性能參數(shù),分析了各偏振參量的定義與物理意義,為后續(xù)對反射率進行衰減訂正提供理論依據(jù)。第二,研究了雙偏振氣象雷達的數(shù)據(jù)獲取過程,分析了影響雷達偏振參量的主要因素,采用徑向連續(xù)性對差分傳播相移進行了預處理,為后續(xù)數(shù)據(jù)分析提高可靠性。第三,提出了一種基于粒子濾波的反射率衰減訂正方法,該方法對激勵噪聲不敏感,在激勵噪聲先驗信息未知的情況下,仍然具有穩(wěn)定的估計結(jié)果,不僅可以準確估計差分傳播相移,使濾波處理后的數(shù)據(jù)具有更好的連續(xù)性、平滑性和準確性,改善了差分傳播相移率的非負性,而且粒子濾波處理后訂正的反射率比較接近真值。第四,提出了基于Kalman-Particle濾波的反射率的高精度衰減訂正方法,當激勵噪聲的先驗信息已知時,該方法能夠獲得精度較高的訂正結(jié)果,與所提的粒子濾波方法相比,經(jīng)過Kalman-Particle濾波方法處理的差分傳播相移與差分傳播相移率更加符合真實氣象環(huán)境,衰減訂正后的反射率更加接近真值,估計精度更高。但是運算量相對較大。
[Abstract]:Meteorological radar is an important means to detect meteorological environment, which is widely used in disaster mitigation and early warning. It evaluates the characteristics of meteorological target according to the change of echo, and it will cause the attenuation of reflectivity when there is a raindrop area on the path. The weather characteristics of the target can not be estimated accurately, and the downfall area may also be inundated. In order to accurately analyze the real characteristics of meteorological targets and improve the accuracy of precipitation estimation, the attenuation correction of reflectivity is needed for the X band with lower frequency. Compared with conventional radar, dual-polarization Doppler radar can provide differential propagation phase shift, which can represent the microphysical properties of particles. The phase shift of differential propagation and rainfall rate are not only highly correlated, but also have the effect of not being hindered by beam propagation. Radar calibration, propagation path attenuation effect, so using differential propagation phase shift for reflectivity attenuation correction has a great advantage. However, the estimation effect of differential propagation phase shift and differential propagation phase shift rate is easily affected by the variable meteorological environment and attenuation polarization parameters, which results in a decrease in the performance of using differential propagation phase shift and attenuation correction of reflectivity in rain area. The difficulty of obtaining prior information also leads to the decrease of the estimation ability of differential propagation phase shift rate, and it is difficult to retain the true meteorological information in the case of low signal-to-noise ratio (SNR). In order to solve the above problems, the correction method of reflectance attenuation in raindrop area proposed in this paper can get a better effect. The main work of this paper is as follows: first, the working principle and main performance parameters of dual-polarization Doppler radar are introduced, and the definition and physical significance of each polarization parameter are analyzed, which provides a theoretical basis for the subsequent correction of reflectivity attenuation. Secondly, the data acquisition process of dual-polarization weather radar is studied, and the main factors affecting the radar polarization parameters are analyzed. The differential propagation phase shift is preprocessed by radial continuity, which improves the reliability of the subsequent data analysis. Thirdly, a reflectivity attenuation correction method based on particle filter is proposed. This method is insensitive to excitation noise, and still has stable estimation results when the priori information of excitation noise is unknown. Not only can the phase shift of differential propagation be estimated accurately, but also the data processed by filter have better continuity, smoothness and accuracy, and the non-negativity of differential propagation phase shift rate can be improved. And the corrected reflectivity of particle filter is close to the true value. Fourthly, a high precision attenuation correction method based on Kalman-Particle filter is proposed. When the priori information of excitation noise is known, the proposed method can obtain higher accuracy correction results, compared with the proposed particle filter method. The differential propagation phase shift and differential propagation phase shift rate processed by the Kalman-Particle filtering method are more in line with the real meteorological environment. The attenuated revised reflectivity is closer to the true value and the estimation accuracy is higher. But the computation is relatively large.
【學位授予單位】：中國民航大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN958

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1 崔愛璐;基于差分傳播相移的Dual-Pol雷達衰減訂正方法研究[D];中國民航大學;2017年

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本文編號：1864755