Understanding Tornadoes and Their Parent Supercells Through Ultra-High Resolution Simulation/Analysis

这项提议是临时分配将于2011年投入使用的Blue Waters计算机系统的时间，并提供差旅费，以支持不同的合作者与Blue Waters项目小组和供应商技术小组进行技术协调。该方法是使用复杂的大气动力学和热力学模型来数值模拟超级单体和不断演变的龙卷风之间的相互作用。这些模拟将解决影响龙卷风演变的小规模、动态活跃的特征，包括浅层流入龙卷风和形成的薄带降水。所使用的数值模式将是一个平行的、风暴尺度的大气模式CM1的发展。这项工作将更好地理解超级单体内部和周围不同环境条件对龙卷风发生和动力学的影响。需要蓝色水域这样规模的资源的理由是，如果没有它，就不可能解决几十米厚的薄降水帷幕，它可能会将大量角动量从云底转移到地面，龙卷风流入层，也有几十米厚，以及低洼冷空气池的影响。要诊断和了解龙卷风发生期间和之后超级单体内部微物理、浮力和涡度动力学之间的相互作用，需要比现有计算系统更高的分辨率。从这个项目中获得的见解应该有助于提高龙卷风预测能力，这有可能通过更早和更准确的警告来增加安全性。更广泛地说，这项研究产生的数据可以用来改进天气尺度模式的次网格参数化，提高它们预报恶劣天气的能力。

This proposal is for a provisional allocation of time on the Blue Waters computer system, due to become operational in 2011, and for travel funds to support technical coordination by various collaborators with the Blue Waters project team and vendor technical team.The project involves a study of the conditions that support tornado development and longevity. The approach is to simulate numerically the interaction between a supercell and an evolving tornado using a sophisticated model of atmospheric dynamics and thermodynamics. These simulations will resolve small-scale, dynamically active features that influence the evolution of the tornado, including the shallow inflow into the tornado and the thin bands of precipitation that form. The numerical model used will be a development of a parallel, storm-scale, atmospheric model named CM1. The work will produce a better understanding of the influence of different environmental conditions within and around the supercell on the genesis and dynamics of tornadoes. The rationale for requiring a resource of the scale of Blue Waters is that, without it, it will not be possible to resolve thin curtains of precipitation, tens of meters thick, which potentially transfer large amounts of angular momentum from cloud-base to ground, the tornado inflow layer, also tens of meters thick, and the influence of low-lying pools of cold air. Being able to diagnose and understand the interplay between microphysics, buoyancy and vorticity dynamics within the supercell, during and after tornado-genesis, requires higher resolution than is possible on existing computing systems.The insights gained from this project should be helpful in improving tornado forecasting capability which has the potential to increase safety through early and more accurate warnings. More general, data generated by this study may be used to improve sub-grid parameterizations for synoptic scale models, improving their ability to forecast severe weather.