Local Enhancement of Extreme Precipitation during Atmospheric Rivers as Simulated in a Regional Climate Model
Local Enhancement of Extreme Precipitation during Atmospheric Rivers as Simulated in a Regional Climate Model
复制标题
区域气候模型模拟的大气河流极端降水的局部增强
DOI：
10.1175/jhm-d-17-0246.1
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发表时间：
2018
影响因子：
3.8
通讯作者：
E. Salathe
中科院分区：
文献类型：
--
作者：
R. Lorente‐Plazas;T. Mitchell;G. Mauger;E. Salathe
本文研究了两个地形特征不同的地区--奥林匹克山脉和普吉特海湾--产生极端降水的天气条件。为了捕捉地形极端降水，在NCEP-NCAR再分析的驱动下，进行了动力降尺度，并对1970-2010年冷季月份进行了评估。将聚类技术应用于区域气候模拟，发现奥林匹克山脉和普吉特海湾是降水量具有明显时间变异性的区域。结果表明，尽管这两个地区位置很近，而且一个地区位于另一个地区的下游，但每个地区约有三分之一的极端降水事件发生在另一个地区，而另一个地区没有发生类似的极端事件。极端降水事件的天气条件组合表明，由于其动力成分(850hPa风)及其热力学成分[综合水汽(IWV)]的不同，综合水汽输送(IVT)存在差异。对于普吉特湾项目，由于风速较低，IVT比奥林匹克山地项目低。与这两个地区极端降水的项目相比，奥运山项目的IVT较低，但在这种情况下，差异是由于较低的IWV和更偏南的风。大尺度条件的这些差异促进了增强每个地点降水的中尺度机制的差异。对于普吉特海湾赛事，静态稳定性较高，且有微弱的雨影。对于奥林匹克山地项目，静态稳定性较低，存在较强的雨影。在这两个地区的极端事件期间，地形调制被最小化，大尺度效应占主导地位。
This paper examines the synoptic conditions that yield extreme precipitation in two regions with different orographic features, the Olympic Mountains and Puget Sound. To capture orographic extreme precipitation, a dynamical downscaling is performed, driven by the NCEP–NCAR reanalysis and evaluated for cool-season months from 1970 to 2010. Clustering techniques are applied to the regional climate simulation, which reveals the Olympic Mountains and Puget Sound as regions with distinct temporal variability in precipitation. Results show that approximately one-third of the extreme precipitation events in each region occur without a similarly extreme event in the other, in spite of the fact that the two areas are very closely located and one is downstream of the other. Composites of synoptic conditions for extreme precipitation events show differences in integrated vapor transport (IVT) due to its dynamical component (winds at 850 hPa) and its thermodynamical component [integrated water vapor (IWV)]. For Puget Sound events, IVT is lower compared to Olympic Mountain events because of lower wind speeds. Olympic Mountain events have lower IVT compared to events with extreme precipitation in both regions, but in this case, the difference is due to lower IWV and more southerly winds. These differences in the large-scale conditions promote differences in the mesoscale mechanisms that enhance precipitation in each location. For Puget Sound events, static stability is higher, and there is a weak rain shadow. For Olympic Mountain events, static stability is lower, and a strong rain shadow is present. During extreme events in both regions, orographic modulation is minimized and large-scale effects dominate.
影响因子：
5.2
作者：
Paltan, Homero;Waliser, Duane;Dadson, Simon
通讯作者：
Dadson, Simon