Mesoscale controls on cumulus convection

积云对流是一个重要的大气过程，在局地尺度上引起恶劣天气，在全球尺度上调节大气环流。尽管这一过程具有根本的重要性，但对它的理解和预测仍然不完整。因此，对恶劣天气的短期预报和对未来气候的预测仍然高度不确定，无法为社会弱势群体提供可靠的指导。我的研究计划的长期目标是提高对积云对流的定量理解，并将这些知识应用于改善天气和气候预测。******这一建议建立在我的研究小组最近对积云对流的物理理解的基础上，特别是对亚云中尺度环流的量化以及这些环流与云层对流之间的紧密联系。特别是，更强的环流会产生更大、更有活力的云，从而更好地克服夹带（吸入环境空气）的抑制作用，上升得更深。******我提出的研究计划提供了多种途径来建立在这种理解的基础上，并将其转化为改进的预测，每个途径都由我指导下的不同研究生进行。首先，将一个有前景的云下中尺度强迫理论模型应用于大尺度模式中这种强迫的预测，以改进它们对对流起始的表示。其次，利用观测系统模拟实验（OSSEs）开发和测试了一种新的观测反演积云夹带方法。第三，在不同的气候条件下，将利用这些数据进行气候学研究，以量化云下强迫和其他环境参数对夹带的影响。第四，利用2015年多伦多泛美运动会的密集观测，量化湖风和其他中尺度过程在控制多伦多周围积云对流中的作用。第五，进行加拿大对流事件的云分辨集合，以了解调节这些事件的多尺度过程，并评估改进短期对流预报的潜在方法。******通过对难以捉摸的过程进行量化的创新思想，以及将新的见解转化为改进的天气和气候预测，我的研究项目使加拿大社会和国际研究界受益。特别是，其科学进步旨在减轻加拿大各地最终用户面临的恶劣天气风险，并缩小目前对未来气候预测的巨大不确定性。多种研究人员的培训也将有助于下一代加拿大自然科学家解决具有区域和世界意义的问题。

Cumulus convection is a critical atmospheric process, causing severe weather on the local scale and regulating the atmospheric circulation on the global scale. Despite the fundamental importance of this process, the understanding and prediction of it remain incomplete. As a result, short-term forecasts of severe weather and future climate projections remain highly uncertain, failing to provide reliable guidance to vulnerable sectors of society. The long-term objective of my research program is to improve the quantitative understanding of cumulus convection and apply that knowledge toward improved weather and climate prediction.******This proposal builds on recent progress by my research group in the physical understanding of cumulus convection, in particular the quantification of sub-cloud mesoscale circulations and the strong links between these circulations and cloud-layer convection. In particular, stronger circulations give rise to larger and more vigorous clouds that better overcome the suppressive effects of entrainment (the ingestion of environmental air) and ascend deeper.******My proposed research program provides multiple pathways to build on this understanding and translate it into improved prediction, each conducted by a different graduate student under my supervision. First, a promising theoretical model of sub-cloud mesoscale forcing will be applied to the prediction of such forcing in large-scale models, to improve their representation of convection initiation. Second, a new observational retrieval of cumulus entrainment will be developed and tested using Observation System Simulation Experiments (OSSEs). Third, climatologies using this retrieval will be conducted to quantify the impacts of sub-cloud forcing and other environmental parameters on entrainment in different climate regimes. Fourth, intensive observations from the 2015 Toronto Pan Am Games will be exploited to quantify the role of lake breezes and other mesoscale processes in controlling cumulus convection around Toronto. Fifth, cloud-resolving ensembles of Canadian convection events will be conducted to understand the multi-scale processes regulating these events and evaluate a potential method for improving short-range convection forecasts.******Through its innovative ideas for the quantification of elusive processes, and for its translation of new insights into improved weather and climate prediction, my research program benefits both Canadian society and the international research community. In particular, its scientific advancements are geared toward mitigating severe-weather risks faced by end-users across Canada and narrowing the currently large uncertainties on future climate projections. The training of multiple research personnel will also contribute to the next generation of Canadian natural scientists tackling problems of regional and worldwide significance.