WRF simulation of downslope wind events in coastal Santa Barbara County
WRF simulation of downslope wind events in coastal Santa Barbara County
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WRF 模拟沿海圣巴巴拉县下坡风事件
DOI：
10.1016/j.atmosres.2017.03.010
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发表时间：
2017
影响因子：
5.5
通讯作者：
M. Jackson
中科院分区：
文献类型：
--
作者：
F. Cannon;L. Carvalho;Charles Jones;T. Hall;David N. Gomberg;J. Dumas;M. Jackson
国家气象局（NWS）认为频繁的阵风下坡风，伴随着快速变暖和相对湿度下降，是影响圣巴巴拉（SB）附近加州南部沿海地区的最重要的天气事件之一。这些极端条件通常被称为“日落”，影响了近年来影响SB的所有主要野火的演变。日落极大地增加了火灾、航空和海上航行的危险，因此是区域预报的优先事项。目前，NWS采用2公里分辨率的天气研究预报（WRF）模式，以补充区域到地方尺度的预报。然而，没有系统的研究已经进行了评估的技能WRF在模拟sundowners.This研究提出了一个案例研究的11天期间，在2004年春季，在此期间，sundowners事件观察到多个夜晚。我们进行敏感性实验WRF使用现有的观测验证，并表明WRF是熟练的，在代表这些事件的一般中尺度结构，虽然存在重要的缺点。此外，我们讨论了在使用最佳性能配置的情况下，研究过程中的日落的生成和演变，并比较这些结果后报两个主要SB火灾。独特的，但类似的，剖面的风和稳定性的观察SB之间的案例研究，尽管在大尺度环流相当大的差异，表明共同的条件可能存在于所有的事件。这些发现有助于了解日落事件的演变，并对事件预测具有潜在价值。
The National Weather Service (NWS) considers frequent gusty downslope winds, accompanied by rapid warming and decreased relative humidity, among the most significant weather events affecting southern California coastal areas in the vicinity of Santa Barbara (SB). These extreme conditions, commonly known as “sundowners”, have affected the evolution of all major wildfires that impacted SB in recent years. Sundowners greatly increase fire, aviation and maritime navigation hazards and are thus a priority for regional forecasting. Currently, the NWS employs the Weather Research Forecasting (WRF) model at 2 km resolution to complement forecasts at regional-to-local scales. However, no systematic study has been performed to evaluate the skill of WRF in simulating sundowners.This research presents a case study of an 11-day period in spring 2004 during which sundowner events were observed on multiple nights. We perform sensitivity experiments for WRF using available observations for validation and demonstrate that WRF is skillful in representing the general mesoscale structure of these events, though important shortcomings exist. Furthermore, we discuss the generation and evolution of sundowners during the case study using the best performing configuration, and compare these results to hindcasts for two major SB fires. Unique, but similar, profiles of wind and stability are observed over SB between case studies despite considerable differences in large-scale circulation, indicating that common conditions may exist across all events. These findings aid in understanding the evolution of sundowner events and are potentially valuable for event prediction.