Understanding the Predictability of Initiation and Morphological Evolution of PECAN (Plains Elevated Convection at Night) Nocturnal Mesoscale Convective Systems

平原夜间高架对流（PECAN）野外活动将于2015年夏季在大平原中部发生。PECAN的科学研究重点是夜间对流，主要研究四个方面：1)夜间对流的发生和中尺度对流团的早期演化；2)钻孔和其他波状扰动；3)夜间中尺度对流系统的动力学和微物理；4)夜间对流发生和演变预报。观测行动计划需要三架研究飞机，七个移动多普勒雷达和多个探测系统。实验设计的一个主要部分是包括固定和移动PECAN综合探测阵列（PISA）单元，该单元由各种剖面仪器组成。PECAN的更广泛的社会影响是提高对水文、能源、农业和公共安全目的的夜间活动的预测。实地活动将包括大量学生，包括努力扩大参与和加强多样性。还将进行公众宣传。通过该奖项，PI Gallus将担任PECAN的首席预报员。为了促进这一作用，我们将使用数据同化运行天气研究与预报（WRF）模型的实时配置。高中尺度对流系统（MCSs），特别是夜间发生的中尺度对流系统，对预报员来说是一个艰巨的挑战。这些事件更难以准确模拟，部分原因是地面以上观测不足，但也因为对它们的发生和维持缺乏了解。MCSs内的初始化和形态演化很可能受到钻孔、升高边界和其他升高辐合带等特征的影响，这些特征在模型中没有很好地初始化，因此这些特征如何调节对流尚不清楚。这些特征通常与低层喷流（LLJ）共存，其模拟也容易受到模拟行星边界层演化误差的影响。这个奖项所获得的工具和知识将有助于更好地理解管理系统。更广泛的影响：这项工作将提高对夜间MCSs升高的理解，从而提高对这些具有挑战性事件的预测，并加强对学生的教育和培训，他们将协助开展研究和现场预测。这项工作有可能直接提高这种天气危害的安全性。

The Plains Elevated Convection at Night (PECAN) field campaign will occur the Summer of 2015 in the central Great Plains. The scientific focus of PECAN is nocturnal convection, with four separate research topics to be addressed: 1) Nocturnal convection initiation and early evolution of mesoscale convective clusters; 2) Bore and other wave-like disturbances; 3) Dynamics and microphysics of nocturnal mesoscale convective systems; 4) Prediction of nocturnal convection initiation and evolution. The observational campaign plan calls for three research aircraft, seven mobile Doppler radars, and multiple sounding systems. A main part of the experimental design is the inclusion of fixed and mobile PECAN Integrated Sounding Array (PISA) units which consists of a variety of profiling instruments. The broader societal impact of PECAN is to improve forecasts of these nocturnal events for hydrology, energy, agriculture and public safety purposes. The field campaign would include a large number of students, including efforts to broaden participation and enhance diversity. Public outreach would also be conducted. Via this award, PI Gallus will serve as lead forecaster for PECAN. To facilitate this role, we will run a real-time configuration of the Weather Research and Forecasting (WRF) model using data assimilation.Intellectual Merit :Elevated mesoscale convective systems (MCSs), particularly those occurring at night, are a difficult challenge for forecasters. These events are more difficult to accurately simulate, partly because of insufficient observations above ground level, but also due to deficiencies in understanding of their initiation and maintenance. Initiation of and morphological evolution within MCSs is likely influenced by features such as bores, elevated boundaries, and other elevated convergence zones that are not initialized well in the models, and thus how these features modulate convection is not well-understood. These features often coexist with low-level jets (LLJ) whose simulation is also sensitive to errors in the simulated planetary boundary layer evolution. Tools and knowledge gained by this award will provide a better understanding of MCSs. Broader Impacts :This work will lead to both improved understanding of elevated nocturnal MCSs that should lead to improved forecasting of these challenging events, and enhanced education and training of students who will assist in conducting the research and also the forecasting in the field. This work has the potential to directly improve safety from this weather hazard.