EAGER: Lift in the Vertical Shear of Southerly Winds: A Mechanism of Elevated Convection at Night in the United States Great Plains

GSTDTAP

项目编号	1924679
	EAGER: Lift in the Vertical Shear of Southerly Winds: A Mechanism of Elevated Convection at Night in the United States Great Plains
	Qi Hu (Principal Investigator)
主持机构	University of Nebraska-Lincoln
项目开始年	2019
	2019-06-01
项目结束日期	2021-05-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	204515(USD)
国家	美国
语种	英语
英文摘要	One of the unique features of warm season weather in the U.S. Great Plains is that heavy precipitation takes place most frequently between midnight and early morning. Such nocturnal heavy precipitation contributes to nearly 80% of daily convective precipitation, critically affecting water resources availability, the economy, and the safety of the communities in the region. This nocturnal heavy precipitation is counterintuitive in the sense that the intensive convective activity over the Great Plains occurs at late night when the lower-troposphere is stably stratified, and the convective available potential energy is low. This paradoxical situation challenges the traditional understanding of development of severe convection yet also presents an opportunity for exploring new mechanisms for severe nocturnal convection and rainfall in the U.S. Great Plains. The goal of this study is to examine a mechanism that initiates nocturnal convection in the absence of passage of fronts or convective complex with a low level of convective available potential energy in the lower troposphere. The significance of outcomes of this study is the exploring of a new mechanism for warm season severe convection and rainfall in the Great Plains at mid-night to early morning hours. The validation of the new mechanism will fill the gap in the knowledge of initiation of nocturnal convection in the absence of frontal boundaries and convective complex and will extend the knowledge of nocturnal convection beyond the traditional thinking. The findings will help improve model capabilities to predict the timing and intensity of severe convection and rainfall in the U.S. Great Plains. The broader impacts of this study also include its potential to improve the safety and wellbeing of the communities across the U.S. Great Plains and, through education, expanding local public schools' science education programs by engaging students in learning fluid dynamics and appreciating the impacts of geosciences in improving people's lives. The central hypothesis is that the nocturnal intensification of the low-level southerly wind in the Great Plains is subject to Coriolis deflection, which would in turn lead to the development of a vortex rotating along the horizontal axis pointing to the north (the northern vortex). Interactions of the northern vortex with the wind blows from the Rockies generate a lift that can elevate air in the lower-troposphere high enough to initiate convection, responsible for heavy precipitation in the hours between mid-night and early morning in the Great Plains. The main research tasks are 1) identifying processes leading to development of the northern vortex; 2) quantifying the condition that creates the lift of the vortex; 3) quantifying the roles of the atmospheric moisture in generating the lift; and 4) identifying the missing or incorrectly described processes that have failed current models in reproducing the elevated convection of this kind. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/213963
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Qi Hu .EAGER: Lift in the Vertical Shear of Southerly Winds: A Mechanism of Elevated Convection at Night in the United States Great Plains.2019.