Vertical velocities at Platteville, Colorado: An intercomparison of simultaneous measurements by the VHF and UHF profilers
Vertical velocities at Platteville, Colorado: An intercomparison of simultaneous measurements by the VHF and UHF profilers
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科罗拉多州普拉特维尔的垂直速度：VHF 和 UHF 剖面仪同时测量的相互比较
DOI：
10.1029/95rs00646
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
R. Strauch
中科院分区：
文献类型：
--
作者：
J. R. McAfee;K. Gage;R. Strauch
风廓线多普勒雷达测量沿雷达波束的“晴朗大气”中运动的径向分量。在较低的VHF(例如，50 MHz)，后向散射过程是高度各向异性的，从垂直入射附近的稳定层返回最大值。相比之下，在超高频，后向散射过程非常接近各向同性。由于散射机制的这些不同，比较配置剖面仪测量的垂直速度是很有意义的，一个在较低的甚高频下工作，另一个在超高频下工作。在科罗拉多州的普拉特维尔开展了一项观测活动，以相互比较两台配置在一起的剖面仪测量的垂直运动。甚高频(50兆赫)风廓线仪在垂直模式下运行，每半小时中断一次，以进行无线电声学探测系统(RASS)测量。超高频(404兆赫)剖面仪以美国中部剖面仪示范网络惯用的低模式和高模式运行。比较了这两个系统在1991年10月和11月所作的观测结果。在8公里以上，垂直运动的总体一致性很好，两个剖面仪都显示了科罗拉多落基山脉背风处的向下平均速度，最大可达6厘米，S−1。在8公里以下，超高频速度系统性地比甚高频速度更向下。这种系统差异归因于水流星对UHF观测的影响，这在每天和每小时的剖面上都可以清楚地看到。
Wind-profiling Doppler radars measure the radial component of motion in the “clear atmosphere” along the radar beam. At lower VHF (e.g., 50 MHz) the backscattering process is highly anisotropic with maximum returns from stable layers near vertical incidence. By contrast, at UHF the backscattering process is very nearly isotropic. Because of these differences in scattering mechanism it is of interest to intercompare vertical velocities measured by collocated profilers, one operating at lower VHF and the other at UHF. An observational campaign was undertaken at Platteville, Colorado, to intercompare vertical motions measured by two collocated profilers. The VHF (50 MHz) wind profiler was operated in a vertical-only mode interrupted every half hour for radio accoustic sounding system (RASS) measurements. The UHF (404 MHz) profiler was operated in low and high modes that are customary for the Demonstration Network of profilers in the central United States. Observations made by these two systems in October and November 1991 are intercompared. The overall agreement in vertical motions is quite good above 8 km with both profilers showing downward mean velocities in the lee of the Colorado Rocky Mountains as large as 6 cm s−1. Below 8 km the UHF velocities are systematically more downward than the VHF velocities. This systematic difference is attributed to the influence of hydrometeors on the UHF observations, as can be seen clearly in daily and hourly profiles.