Multiscale Studies of Synoptic and Mesoscale Disturbances Over the North Pacific, North America, and North Atlantic

根据该合同，首席研究员将对中纬度和热带扰动的生命周期进行多尺度（时间和空间）观测和数值研究。这项研究的动机是最近完成的和正在进行的国家科学基金会支持的调查结果，这些调查表明：(1)重要的中纬度天气系统的生命周期可以由环绕全球的对流层上层的长期连贯扰动控制，而这些扰动反过来又受到行星尺度流的配置和演变的影响；(2)中纬度扰动可通过冷潮影响热带地区，导致信风、东风和副热带急流加速；(3)南极海岸附近极锋急流的出现和消失是南半球澳大利亚-新西兰区冬季分裂急流存在的原因；(4)太平洋风暴路径末端的风暴在穿越北美西部时遵循优先路径；(5)在暖季、准静止的中纬度大陆反气旋周围顺时针旋转的高空中尺度位涡异常可以触发中尺度对流系统的形成，在某些情况下，这些对流系统可能与早期热带风暴有关。对这些主题的持续研究将继续进行。新的研究将主要集中在热带气旋的温带转变研究上。新的再分析数据集和新的遥感卫星观测（例如，对流层上层水汽风和先进的微波测深仪单元辐射，可以揭示热带气旋的暖核）将发挥优势。这些新的数据集和观测资料的可用性应允许，例如，检查过境热带气旋的结构（例如，暖核到冷核；对称到不对称），以努力了解可能导致风暴爆炸性再增强潜力的因素。案例将从过去和未来难以预测的过渡风暴中提取。研究方法将以正在进行的工作为基础，并将包括观察和建模两部分。

Under this award, the Principal Investigator will undertake multiscale (time and space) observational and numerical studies of the life cycles of mid-latitude and tropical disturbances. This research is motivated by the results of recently completed and ongoing NSF supported investigations that have demonstrated how: (1) the life cycles of significant mid-latitude weather systems can be controlled by long-lived coherent disturbances in the upper troposphere that circumnavigate the globe and in turn are influenced by the configuration and evolution of the planetary-scale flow; (2) mid-latitude disturbances can impact the tropics through cool surges that lead to an acceleration of the trade wind easterlies and the subtropical jet; (3) how the winter-season split jet in the Australia-New Zealand sector of the Southern Hemisphere owes its existence to the appearance and disappearance of the polar-front jet near the coast of Antarctica; (4) storms at the end of the Pacific storm track follow preferential pathways as they move across western North America, and (5) mesoscale potential vorticity anomalies aloft that rotate clockwise around warm-season, quasi-stationary mid-latitude continental anticyclones can trigger the formation of mesoscale convective systems that in some cases can become associated with incipient tropical storms. Ongoing research on these topics will continue.New research will focus primarily on studies of the extratropical transition of tropical cyclones. Advantage will be taken of new reanalysis data sets and new remotely sensed satellite observations (e.g., upper troposphere water vapor winds and advanced microwave sounder unit-radiances that can reveal warm cores in tropical cyclones). The availability of these new data sets and observations should permit, for example, an examination of the structure of transiting tropical cyclones (e.g., warm to cold core; symmetric to asymmetric) in an effort to understand the factors that may contribute to the explosive reintensification potential of the storms. Cases will be drawn from past and future difficult-to-predict transitioning storms. The research methodology will be based upon ongoing work and will involve both an observational and a modeling component.