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首页> 外文学位 >Attenuation Correction of X-band Polarimetric Doppler Weather Radar Signals: Application to Systems with High Spatio-Temporal Resolution.
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Attenuation Correction of X-band Polarimetric Doppler Weather Radar Signals: Application to Systems with High Spatio-Temporal Resolution.

机译：X波段极化多普勒天气雷达信号的衰减校正：在具有高时空分辨率的系统中的应用。

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摘要

In the last decade the atmospheric science community has seen widespread and successful application of X-band dual-polarization weather radars for measuring precipitation in the lowest 2 km of the troposphere. These X-band radars have the advantage of a smaller footprint, lower cost, and improved detection of hydrometeors due to increased range resolution. In recent years, the hydrology community began incorporating these radars in novel applications to study the spatio-temporal variability of rainfall from precipitation measurements near the ground, over watersheds of interest. The University of Iowa mobile XPOL radar system is one of the first to be used as an X-band polarimetric radar network dedicated to hydrology studies. During the spring of 2013, the Iowa XPOL radars participated in NASA Global Precipitation Measurement's (GPM) first field campaign focused solely on hydrology studies, called the Iowa Flood Studies (IFloodS). Weather radars operating in the 3.2 cm (X-band) regime can suffer from severe attenuation, particularly in heavy convective storms. This has led to the development of sophisticated algorithms for X-band radars to correct the meteorological observables for attenuation. This is especially important for higher range resolution hydrology-specific X-band weather radars, where the attenuation correction aspect remains relatively unexamined. This research studies the problem of correcting for precipitation-induced attenuation in X-band polarimetric weather radars with high spatio-temporal resolution for hydrological applications. We also examine the variability in scattering simulations obtained from the drop spectra measured by two dimensional video disdrometers (2DVD) located in different climatic and geographical locations. The 2DVD simulations provide a ground truth for various relations (e.g., AH-KDP and AH-ADP) applied to our algorithms for estimating attenuation, and ultimately correcting for it to provide improved rain rates and hydrometeor identification. We developed a modified ZPHI attenuation correction algorithm, with a differential phase constraint, and tuned it for the high resolution IFloodS data obtained by the Iowa XPOL radars. Although this algorithm has good performance in pure rain events, it is difficult to fully correct for attenuation and differential attenuation near the melting layer where a mixed phase of rain and melting snow or graupel exists. To identify these regions, we propose an improved iterative FIR range filtering technique, as first presented by Hubbert and Bringi (1995), to better estimate the differential backscatter phase, delta, due to Mie scattering at X-band from mixed phase precipitation. In addition, we investigate dual-wavelength algorithms to directly estimate the alpha and beta coefficients, of the AH = alpha * KDP and ADP = beta * KDP relations, to obtain the path integrated attenuation due to rain and wet ice or snow in the region near the melting layer. We use data from the dual-wavelength, dual-polarization CSU-CHILL S-/X-band Doppler weather radar for analyzing the coefficients and compare their variability as a function of height, where the hydrometeors are expected to go through a microphysical transformation as they fall, starting as snow or graupel/hail then melting into rain or a rain-hail mixture. The S-band signal is un-attenuated and so forms a reference for estimating the X-band attenuation and differential attenuation. We present the ranges of the alpha and beta coefficients in these varying precipitation regimes to help improve KDP-based attenuation correction algorithms at X-band as well as rain rate algorithms based on the derived AH.
机译：在过去的十年中，大气科学界已经广泛使用X波段双极化天气雷达来成功测量对流层最低2 km的降水。这些X波段雷达的优势是占地面积更小，成本更低，并且由于增加了距离分辨率而改善了对水凝物的探测。近年来，水文学界开始将这些雷达应用到新颖的应用中，以研究目标流域附近地面降水量测量降雨的时空变化。爱荷华大学的移动XPOL雷达系统是最早用作专门用于水文学研究的X波段极化雷达网络的系统之一。在2013年春季，爱荷华州XPOL雷达参加了美国宇航局全球降水测量（GPM）的首次野外活动，该活动专门针对水文学研究，称为爱荷华州洪水研究（IFloodS）。在3.2厘米（X波段）范围内运行的天气雷达可能会遭受严重的衰减，特别是在强对流风暴中。这导致开发用于X波段雷达的复杂算法，以校正气象观测值的衰减。这对于更高范围分辨率的水文专用X波段气象雷达尤其重要，因为在该雷达中，衰减校正方面仍未得到检查。这项研究研究了校正在水文应用中具有高时空分辨率的X波段极化气象雷达中降水引起的衰减的问题。我们还检查了散射模拟的可变性，这些散射模拟是由位于不同气候和地理位置的二维视频测速仪（2DVD）通过测得的液滴光谱获得的。 2DVD模拟为我们应用于估算衰减的算法的各种关系（例如AH-KDP和AH-ADP）提供了基本事实，并最终对其进行了校正以提供改进的降雨率和水凝气象识别。我们开发了一种改进的具有差分相位约束的ZPHI衰减校正算法，并针对爱荷华州XPOL雷达获得的高分辨率IFloodS数据进行了调整。尽管此算法在纯雨事件中具有良好的性能，但是很难完全校正存在雨水和融雪或gra的混合相的融化层附近的衰减和微分衰减。为了识别这些区域，我们提出了一种改进的迭代FIR范围滤波技术，该技术首先由Hubbert和Bringi（1995）提出，以更好地估计由于混合相在X波段的Mie散射而引起的差分反向散射相位delta。此外，我们研究了双波长算法以直接估算AH = alpha * KDP和ADP = beta * KDP关系的alpha和beta系数，以获得该区域由于雨，湿冰或雪造成的路径积分衰减在熔化层附近。我们使用来自双波长，双极化CSU-CHILL S // X波段多普勒天气雷达的数据来分析系数，并比较其随高度变化的可变性，其中水凝物预计将经历微物理转换，如它们从雪或雨滴/冰雹开始落下，然后融化成雨水或雨-冰雹混合物。 S波段信号未衰减，因此构成了估算X波段衰减和差分衰减的参考。我们介绍了这些变化的降水方式中的alpha和beta系数的范围，以帮助改进X波段上基于KDP的衰减校正算法以及基于派生AH的降雨率算法。

著录项

  • 作者

    Galvez, Miguel Bustamante.;

  • 作者单位

    Colorado State University.;

  • 授予单位 Colorado State University.;
  • 学科 Electrical engineering.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 122 p.
  • 总页数 122
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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