Rain versus Snow in the Sierra Nevada, California: Comparing Doppler Profiling Radar and Surface Observations of Melting Level
Rain versus Snow in the Sierra Nevada, California: Comparing Doppler Profiling Radar and Surface Observations of Melting Level
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DOI：
10.1175/2007jhm853.1
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发表时间：
2008-04
影响因子：
3.8
通讯作者：
J. Lundquist;D. Gottas
中科院分区：
文献类型：
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作者：
J. Lundquist;D. Gottas
摘要北美西部的海洋山脉海拔范围很广，对温暖的冬季风暴引发的洪水极其敏感，主要是因为降雨落在更高的海拔上，而且与典型的风暴期间相比，降雨覆盖的盆地贡献面积要大得多。对这条雨雪线的准确预报对水文预报至关重要。这项研究考察了如何使用在山脉上游测量的遥感大气雪层(具体地说，在雷达风廓线上方测量的明亮波段)来准确描述沿山脉迎风坡面从雪到雨的表面转变的高度，重点是2001年至2005年在加利福尼亚州内华达山脉进行的测量。积雪的积累与地表温度、太阳辐射的日循环以及自由对流层融化水平的波动有关。在1.5℃时，50%的降水事件落在雨中，50%的降水事件落在雪中，平均而言，50%的实测降水事件是降雪。
Abstract The maritime mountain ranges of western North America span a wide range of elevations and are extremely sensitive to flooding from warm winter storms, primarily because rain falls at higher elevations and over a much greater fraction of a basin’s contributing area than during a typical storm. Accurate predictions of this rain–snow line are crucial to hydrologic forecasting. This study examines how remotely sensed atmospheric snow levels measured upstream of a mountain range (specifically, the bright band measured above radar wind profilers) can be used to accurately portray the altitude of the surface transition from snow to rain along the mountain’s windward slopes, focusing on measurements in the Sierra Nevada, California, from 2001 to 2005. Snow accumulation varies with respect to surface temperature, diurnal cycles in solar radiation, and fluctuations in the free-tropospheric melting level. At 1.5°C, 50% of precipitation events fall as rain and 50% as snow, and on average, 50% of measured pre...