The Mississippi Valley Convection Minimum on Summer Afternoons: Observations and Numerical Simulations
The Mississippi Valley Convection Minimum on Summer Afternoons: Observations and Numerical Simulations
复制标题
夏季下午密西西比河谷对流最小：观测和数值模拟
DOI：
10.1175/mwr-d-15-0238.1
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发表时间：
2016
影响因子：
3.2
通讯作者：
Q. Cazenave
中科院分区：
文献类型：
--
作者：
D. Kirshbaum;F. Fabry;Q. Cazenave
对美国大陆上空15年合成雷达图像的分析表明，夏季下午，相对于周边地区，密西西比河谷下部的深对流发生率明显最低。为了了解这种对流签名背后的机制，准理想化的数值模拟与天气研究和预报（WRF）模式进行。模拟，广泛地再现山谷对流最小值，表明对流抑制最大化，低层上升最小化，在平坦的山谷地形。相反，较弱的抑制和较强的机械强迫上升超过山谷两侧的山丘联合收割机结合起来，更容易启动对流。虽然该地区的地形是不显着的，它对区域对流模式的影响比土地利用的变化。
AbstractAnalysis of 15 years of composite radar images over the continental United States reveals a distinct minimum of deep-convection occurrence over the interior lower Mississippi Valley on summer afternoons, relative to surrounding areas. To understand the mechanisms behind this convection signature, quasi-idealized numerical simulations with the Weather Research and Forecasting (WRF) Model are performed. The simulations, which broadly reproduce the valley convection minimum, suggest that convective inhibition is maximized, and low-level ascent minimized, over the flat valley terrain. By contrast, weaker inhibition and stronger mechanically forced ascent over the hills flanking the valley combine to initiate convection more readily. Although the orography of the region is unremarkable, it has a stronger influence on the regional convection pattern than do variations in land use.