Investigation of observational error sources in multi Doppler radar vertical air motion retrievals: Impacts and possible solutions
Investigation of observational error sources in multi Doppler radar
vertical air motion retrievals: Impacts and possible solutions
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多普勒雷达垂直空气运动反演中观测误差源的调查：影响和可能的解决方案
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
T. Matsui
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作者：
M. Oue;P. Kollias;A. Shapiro;A. Tatarevic;T. Matsui
抽象的。在过去的几十年里，多多普勒雷达网络观测已被用于不同的配置，以进行中尺度对流系统的三维风反演。本文利用天气研究与预报（WRF）模式模拟，研究了所选雷达体积覆盖模式（VCP）、VCP采样时间、雷达数量和平流订正附加值对对流云上部垂直运动反演的影响。云分辨模式雷达模拟器（CR-SIM）和三维变分多多普勒雷达反演技术。模型真实值之间的比较（即，WRF运动场）和上升气流的属性（上升气流分数，上升气流的大小，和质量通量）检索从CR-SIM产生的多多普勒雷达场被用来调查这些影响。总体而言，VCP的海拔战略和采样时间被发现有显着的影响，在6公里以上的高度反演的上升气流的属性。使用2分钟或更短的VCP进行检索显示上升气流检索的影响很小，和使用快照云场检索的错误是可比的。增加仰角密度和/或增加来自另一个雷达的数据可以减少这种不确定性。研究发现，如果在2分钟内进行VCP，则具有密集仰角的VCP似乎比来自第四雷达的数据的添加更有效。使用密集的仰角结合平流校正应用于2分钟VCP可以有效地提高上升气流反演。对于较长的VCP采样周期（5分钟）的误差是相当大的，平流校正的值是具有挑战性的，由于在模拟的中尺度对流系统的动力结构的快速变形。这项研究突出了几个限制因素在检索上层垂直速度从多多普勒雷达网络，并建议使用快速扫描雷达可以大大提高风检索的质量，如果在有限的空间域进行。
Abstract. Multi-Doppler radar network observations have been used in different configurations over the last several decades to conduct three-dimensional wind retrievals in mesoscale convective systems. Here, the impact of the selected radar volume coverage pattern (VCP), the sampling time for the VCP, the number of radars used, and the added value of advection correction on the retrieval of the vertical air motion in the upper part of convective clouds is examined using the Weather Research and Forecasting (WRF) model simulation, the Cloud Resolving Model Radar SIMulator (CR-SIM) and a three-dimensional variational multi-Doppler radar retrieval technique. Comparisons between the model truth (i.e., WRF kinematic fields) and updraft properties (updraft fraction, updraft magnitude, and mass flux) retrieved from the CR-SIM-generated multi-Doppler radar field are used to investigate these impacts. In overall, the VCP elevation strategy and sampling time is found to have a significant effect on the retrieved updraft properties above 6 km altitude. Retrievals conducted using a 2-min or shorter VCPs show small impacts on the updraft retrievals, and the errors are comparable to retrievals using a snapshot cloud field. Increasing the density of elevations angles and/or an addition of data from one more radar can reduce this uncertainty. It is found that the VCP with dense elevation angles appears to be more effective than the addition of data from the fourth radar, if the VCP is performed in 2 minutes. The use of dense elevation angles combined with an advection correction applied to the 2-min VCPs can effectively improve the updraft retrievals. For longer VCP sampling periods (5 min) the errors are considerably larger, and the value of advection correction is challenging due to the rapid deformation of the dynamical structures in the simulated mesoscale convective system. This study highlights several limiting factors in the retrieval of upper-level vertical velocity from multi-Doppler radar networks and suggests that the use of rapid-scan radars can substantially improve the quality of wind retrievals if conducted in a limited spatial domain.