Mesoscale controls on cumulus convection

积云对流是一种重要的大气过程，它在局地尺度上引起灾害性天气，在全球尺度上调节大气环流。 尽管这一过程至关重要，但对它的理解和预测仍然不完整。 因此，恶劣天气的短期预报和未来气候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在积云对流的物理理解方面取得的进展，特别是云下中尺度环流的量化以及这些环流与云层对流之间的密切联系。 特别是，更强的环流会产生更大、更活跃的云，更好地克服夹带（环境空气的摄入）的抑制作用，并上升得更深。我提出的研究计划提供了多种途径来建立这种理解，并将其转化为改进的预测，每一个都由我监督下的不同研究生进行。首先，一个有前途的理论模式的云下中尺度强迫将被应用到预测这种强迫在大尺度模式，以提高其代表性的对流启动。 第二，一个新的观测反演积云卷吸将开发和测试使用观测系统模拟实验（OSSEs）。第三，使用这种检索的气候学将进行量化的影响，云下强迫和其他环境参数的夹带在不同的气候制度。 第四，将利用2015年多伦多泛美运动会的密集观测来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，将进行加拿大对流事件的云解析集合，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。通过量化难以捉摸的过程的创新理念，以及将新的见解转化为改进的天气和气候预测，我的研究计划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终端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。 培训多名研究人员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.