Collaborative Research: Climatological and Event-Based Radar Delineation of UHI Convection for Urban Corridors Within the Southeastern U.S.

天气损失的增加部分可归因于美国恶劣天气更为常见的地区人口密度更大。 在这些观测所涉及的广泛尺度上，恶劣天气事件的频率和强度变化与人类引起的气候变化没有明确的联系。 然而，在较小的尺度上，例如人口集中的城市地区，人为的天气变化更为突出。 这项调查研究了城市热岛如何增强美国东南部一系列城市之间的对流。这项研究为美国东南部多城市地区开发了一种基于雷达的暖季对流气候学，在过去的二三十年里，城市人口大量增加。 研究人员将开发一种城市/农村雷达反射率气候学，以表征几个城市和农村控制区的对流分布。 通过同时评估的反射率模式周围的六个不同大小的城市加上两个控制区域下定义的暖季大气环境，比较合成将开发的城市热岛相关的对流在哪里和在什么强度的演变，并在城市的外围。 然后，调查人员将比较和对比这些地点的城市/农村雷达反射率最大值，并将它们与雷暴危害联系起来。 最后，将开发一种基于雷达的单元格跟踪仪器，用于分析个别城市热岛增强事件。 该仪器将评估这些事件的方向，气象环境，其演变相对于土地利用和elevation.This研究项目将提供城市热岛对流如何在不同规模和地形的城市变化的第一个地理合成。 通过根据其反射率水平对对流事件进行分层，这是风暴对恶劣天气倾向的替代品，研究人员将开发一套观测结果，可以告知研究人员和从业人员城市如何增强和减轻风暴强度，重新定向它们的运动，并创建雷暴活动的热点。 一个更复杂的观点，不同的土地覆盖对对流风暴的影响，预计将出现从这项研究中，其中的相互作用的表面特性，土地利用，和城市修改天气模式产生更多的地理变异的雷暴强度和相关的危害。 城市热岛增强是基本了解土地覆盖对形成雷暴和灾害分布的作用的重要组成部分。 此外，由于预测在人为全球变暖的情况下，雷暴频率增加，城市雷暴可能会放大天气和灾害规划政策的经济相关性。 这项研究将使研究人员和从业人员能够调整和部署一个方法模板，用于持续监测城市环境中的雷暴。

Increases in weather losses can, in part, be attributable to greater population densities in regions of the U.S. where severe weather is more common. At the broad scales over which these observations have been made, changes in the frequency and intensity of severe weather events are not clearly linked to human-induced climate change. At the smaller scales, however, such as urban regions where population is concentrated, human-induced modification of weather is more prominent. This investigation examines how the urban heat island augments convection among a range of cities in the southeastern U.S. The study develops a radar-based, warm-season climatology of convection for a multi-city region in the southeastern U.S., a thunderstorm-prone area that has seen substantial increases in urban population over the last two to three decades. The investigators will develop an urban/rural radar reflectivity climatology that will characterize the distribution of convection across several cities and rural control regions. By simultaneously assessing the patterns of reflectivity around six different sized cities plus two control regions under defined warm-season atmospheric environments, a comparative synthesis will be developed of where and at what intensities urban heat island-associated convection evolves over and in the periphery of cities. The investigators then will compare and contrast urban/rural radar reflectivity maximums for these locations and associate them with thunderstorm hazards. Finally, the development of a radar-based cell-tracking instrument will provide for the analysis of individual urban heat island enhanced events. This instrument will assess these events in terms of their orientation, meteorological setting, and their evolution relative to land use and elevation.This research project will provide the first geographic synthesis of how urban heat island convection varies across cities of different sizes and topography. By stratifying convective events according to their reflectivity level, which is a surrogate of a storm's propensity for severe weather, the investigators will develop a set of observations that can inform researchers and practitioners regarding how cities enhance and lessen storm intensity, redirect their motion, and create hotspots of thunderstorm activity. A more complex view of the effects of differing land cover on convective storms is expected to emerge from this study, one in which interaction of surface properties, land-use, and urban modified weather patterns yield more geographic variability in thunderstorm intensity and associated hazards. The urban heat island enhancement is an important component in basic understanding of the role of land cover on shaping the distribution of thunderstorms and hazards. Furthermore, given predicted increases in thunderstorm frequency under a scenario of human-induced global warming, urban thunderstorms may amplify the economic relevance to weather and hazard planning policy. This research will permit researchers and practitioners to tune and deploy a methodological template for continued monitoring of thunderstorms in urban settings.