The Dynamical Linkage of Atmospheric Blocking to Drought, Heatwave and Urban Heat Island in Southeastern US: A Multi-Scale Case Study
The Dynamical Linkage of Atmospheric Blocking to Drought, Heatwave and Urban Heat Island in Southeastern US: A Multi-Scale Case Study
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DOI：
10.3390/atmos9010033
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发表时间：
2018-01-01
期刊：
影响因子：
2.9
通讯作者：
Burt, Ethan
中科院分区：
文献类型：
--
作者：
Dong, Li;Mitra, Chandana;Burt, Ethan
大气阻塞是一种长期存在于对流层中层的结构，通常与干旱、热浪、洪水和冷空气爆发等极端天气事件有关。2007年8月13日至17日，美国上空持续存在一个引人注目的大气阻塞，加剧了美国东南部现有的干旱。这一明显的阻塞事件不仅加剧了同时发生的干旱状况，还导致美国东南部出现破纪录的热浪。在这场热浪中观测到的过量热量可归因于与沉降相关的绝热变暖以及亚拉巴马和邻近州上空的干热空气平流。在局地尺度上，我们选择阿拉巴马州的伯明翰作为研究区域，探讨阻塞对城市热岛的影响。基于遥感数据，在阻塞发生日，该地区的表面（皮肤）城市热岛为8 ℃。这提供了部分证据表明，地面城市热岛强度可能是由阻塞引起的热浪放大。目前的工作提供了一个独特的案例研究，其中阻塞，干旱，热浪和城市热岛都同时发生，并在空间尺度的频谱相互作用。我们的结论是，大气阻塞是能够加强干旱，引发热浪，并可能放大城市热岛强度在同期。
Atmospheric blocking is a long standing structure stalled in the mid-troposphere which is often associated with extreme weather events such as droughts, heatwaves, flood and cold air outbreak. A striking atmospheric blocking is identified to persist over the US during 13-17 August 2007, exacerbating the existing drought over the Southeastern US. This pronounced blocking event not only intensified the concurrent drought conditions, but also led to a record-breaking heatwave over the Southeast of the US. The excessive heat observed during this heatwave is attributable to the subsidence-associated adiabatic warming as well as the dry-and-warm air advection over Alabama and the neighboring states. At the local scale, we choose Birmingham, AL, as the study area for exploring the blocking influence on urban heat island. Based on the remote sensing data, the surface (skin) urban heat island is found to be 8 C in this area on the block-onset day. This provides partial evidences that the surface urban heat island intensity is likely amplified by the blocking-induced heat waves. The present work provides a unique case study in which blocking, drought, heatwave and urban heat island all occur concurrently, and interplay across a spectrum of spatial scales. We conclude that atmospheric blocking is capable of reinforcing droughts, initiating heatwaves, and probably amplifying the urban heat island intensity during the concurrent period.