Using TRMM spaceborne radar as a reference for compensating ground‐based radar range degradation: Methodology verification based on rain gauges in Israel
Using TRMM spaceborne radar as a reference for compensating ground‐based radar range degradation: Methodology verification based on rain gauges in Israel
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DOI：
10.1029/2010jd014496
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发表时间：
2011-01
影响因子：
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通讯作者：
M. Gabella;E. Morin;R. Notarpietro
中科院分区：
文献类型：
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作者：
M. Gabella;E. Morin;R. Notarpietro
[1] 虽然大量的科学工作集中在温带气候条件下的雷达降水估算，但相对较少的研究考察了干燥气候地区。本文研究了以色列 19 天降雨期的雨深估计，其中雨量计空间分布特别不均匀。这一事实加剧了雨量计观测的主要缺点，即采样不足。地基气象雷达（GR）可以补充有关降水分布的所需信息。然而，特别是在复杂的地形区域，雷达科学家面临着波束随距离变宽、波束填充不均匀、部分波束掩星以及垂直反射率剖面变化的问题。本文提出了基于星载气象雷达的范围调整对 GR 降水估计的改进。过去，热带降雨测量任务（TRMM）卫星雷达被用来检查世界各地的GR平均场偏差。然而，据我们所知，由于使用经过良好校准的 Ku 波段 TRMM 雷达作为参考得出的平均场偏差和与距离相关的补偿，GR 得出的累积降雨量首次与测量仪显示出更好的一致性。平均偏差从+1.0 dB改善至-0.3 dB；更有趣且更难获得的是误差分散度的减小。使用基于 TRMM 的范围补偿，散射从 2.21 dB 减少到 1.93 dB。我们的结论是，尝试补偿 GR 范围的下降是非常值得的。
[1] While intense scientific efforts have focused on radar precipitation estimation in temperate climatic regimes, relatively few studies have examined dry climatic regions. This paper examines rain depth estimation for a 19 day rainfall period in Israel, where the gauge spatial distribution is particularly nonhomogeneous. This fact exacerbates the main drawback of rain gauge observations, which is undersampling. Meteorological ground-based radar (GR) can supplement the desired information on precipitation distribution. However, especially in a complex orographic region, radar scientists are faced with beam broadening with distance, nonhomogeneous beam filling, and partial-beam occultation, together with changes in the vertical reflectivity profile. This paper presents an improvement of GR precipitation estimates thanks to a range adjustment based on spaceborne meteorological radar. In the past, the Tropical Rainfall Measuring Mission (TRMM) satellite radar was used for checking the GR mean field bias around the world. To our knowledge, however, it is the first time that GR-derived cumulative rainfall amounts show a better agreement with gauges, thanks to the mean field bias and range-dependent compensation derived using the well-calibrated Ku band TRMM radar as a reference. The average bias improves from +1.0 dB to −0.3 dB; more interesting and difficult to obtain is a reduction of the dispersion of the error. Using TRMM-based range compensation, the scatter decreases from 2.21 dB to 1.93 dB. We conclude that it is well worth trying to compensate for the GR range degradation.