Antecedent North Pacific Jet Regimes Conducive to the Development of Continental U.S. Extreme Temperature Events during the Cool Season
Antecedent North Pacific Jet Regimes Conducive to the Development of Continental U.S. Extreme Temperature Events during the Cool Season
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先前的北太平洋急流状况有利于美国大陆冷季极端温度事件的发展
DOI：
10.1175/waf-d-18-0168.1
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发表时间：
2019
影响因子：
2.9
通讯作者：
Keyser, Daniel
中科院分区：
文献类型：
--
作者：
Winters, Andrew C.;Bosart, Lance F.;Keyser, Daniel
这项研究认为，美国大陆的发展极端温度事件（ETEs）在凉爽的季节（9月至5月），极端温度的定义在极端温度的空间覆盖范围和事件的定义。在确定ETE之后，将其分为地理集群，并使用NPJ相图根据埃特启动之前的北太平洋急流（NPJ）流的状态进行分层。NPJ相图是由冷季NPJ变化的两个主要模态发展而来的。第一模态对应于气候NPJ出口区域的纬向延伸或收缩，而第二模态对应于气候NPJ出口区域的向极或向赤道移动。250百帕纬向风异常的投影到NPJ相图之前ETE表明，NPJ的首选状态和演变之前ETE变化很大的基础上的地理位置的埃特启动和季节。然而，南部平原的极端温暖事件是一个例外，因为该地区的极端温暖事件在所有季节都是在NPJ收缩后开始的。NPJ相图随后被用来检查天气尺度的流动演变非常有利于启动南部平原极端温暖的事件，通过合成分析。复合分析表明，一个收缩的NPJ支持北美上空对流层上层流型的放大，然后在埃特启动之前在南部平原上空诱导持续的对流层下层暖空气平流。
This study considers the development of continental U.S. extreme temperature events (ETEs) during the cool season (September–May), where extreme temperatures are defined in terms of percentiles and events are defined in terms of the spatial coverage of extreme temperatures. Following their identification, ETEs are classified into geographic clusters and stratified based on the state of the North Pacific jet (NPJ) stream prior to ETE initiation using an NPJ phase diagram. The NPJ phase diagram is developed from the two leading modes of NPJ variability during the cool season. The first mode corresponds to a zonal extension or retraction of the exit region of the climatological NPJ, while the second mode corresponds to a poleward or equatorward shift of the exit region of the climatological NPJ. The projection of 250-hPa zonal wind anomalies onto the NPJ phase diagram prior to ETEs demonstrates that the preferred state and evolution of the NPJ prior to ETEs varies considerably based on the geographic location of ETE initiation and the season. Southern plains extreme warm events are an exception, however, since extreme warm events in that location most frequently initiate following a retracted NPJ during all seasons. The NPJ phase diagram is subsequently utilized to examine a synoptic-scale flow evolution highly conducive to the initiation of southern plains extreme warm events via composite analysis. The composite analysis demonstrates that a retracted NPJ supports an amplification of the upper-tropospheric flow pattern over North America, which then induces persistent lower-tropospheric warm-air advection over the southern plains prior to ETE initiation.
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影响因子：
8.9
作者：
C. Grams;H. Wernli;M. Böttcher;J. Čampa;U. Corsmeier;S. Jones;J. Keller;C. Lenz;L. Wiegand-
通讯作者：
C. Grams;H. Wernli;M. Böttcher;J. Čampa;U. Corsmeier;S. Jones;J. Keller;C. Lenz;L. Wiegand-
佛罗里达柑橘面临冰冻风险。
DOI：
--
发表时间：
1993
期刊：
影响因子：
--
作者：
Mary W. Downton;K. Miller
通讯作者：
K. Miller
影响因子：
3.2
作者：
Cordeira, Jason M.;Ralph, F. Martin;Moore, Benjamin J.
通讯作者：
Moore, Benjamin J.
影响落基山脉以东冷空气爆发的因素
DOI：
--
发表时间：
1991
期刊：
影响因子：
--
作者：
G. Hartjenstein;R. Bleck
通讯作者：
R. Bleck
与北太平洋急流变化的时间相干模式相关的天气特征
DOI：
--
发表时间：
2017
期刊：
影响因子：
--
作者：
Kyle S. Griffin;Jonathan E. Martin
通讯作者：
Jonathan E. Martin