Extreme temperature days in the south-central United States
Extreme temperature days in the south-central United States
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DOI：
10.3354/cr008151
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发表时间：
1997-05-08
期刊：
影响因子：
1.1
通讯作者：
Muller, RA
中科院分区：
文献类型：
--
作者：
Henderson, KG;Muller, RA
美国中南部的极端高温天气可能会对能源需求、农业和人类舒适度产生重大影响。在本文中，极端日的定义是超过该日长期平均气温的1个标准差的一天。使用这种方法，发现每个季节都会出现类似数量的极端日。从历史气候网络每日(HCN/D)记录中选择了16个站来代表B州地区的情况。各站极端日的时间序列均存在明显的季节间和年际变化。在冬天，每年大约有10到15天是温暖的。然而，这两种类型的事件都不会持续很长时间。这种模式表明，在这个季节，活跃的大气环流在中纬度地区移动锋面和气团。冬季寒冷日数较多，与北美大范围经向环流有关，而冬季纬向气流产生较频繁的温暖日数。在夏季，每年有规律地出现寒冷的日子，但寒冷的天气是短暂的。然而，温暖的事件遵循着一种非常不同的模式。温暖的白天频率在夏季变化更大，当温暖事件确实发生时，它们往往会持续更长的时间。夏季冷暖日数频繁的大尺度环流差异较小，表明区域尺度的副热带气流格局和大西洋副热带高压的扩张可能是夏季重要的强迫因子。在这个世纪里，有一种长期的趋势，即所有季节的寒冷天气都会更加频繁。然而，在过去十年中，这一趋势可能正在逆转。
Extreme temperature days in the south-central United States can have significant impacts on energy demand, agriculture, and human comfort. In this paper an extreme day is defined as a day that exceeds 1 standard deviation of the long-term average temperature for that day. Using this methodology, similar numbers of extreme days are found to occur in each season. Sixteen stations are selected from the Historical Climate Network Daily (HCN/D) record to represent conditions across a B-state region. Significant interseasonal and interannual variability are found in the time-series of extreme days at all stations. In winter approximately 10 to 15 warm and told days occur each year. However, neither type of event persists for long periods of time. This pattern is indicative of the vigorous atmospheric circulation that moves fronts and air masses through the midlatitudes during this season. Winters with a high frequency of cold days are associated with large-scale meridional circulation over North America, while zonal flow in winter produces more frequent warm days. In summer cold days occur regularly each year but cold events are short-lived. Warm events, however, follow a very different pattern. Warm day frequency is much more Variable in the summer, and warm events tend to persist for longer periods of time when they do occur. Large-scale circulation differences between summers with frequent warm and cold days are weak, indicating that regional-scale patterns of subtropical flow and the expansion of the Atlantic Subtropical High are most likely important forcing factors in summer. Over this century there is a long-term trend toward more frequent cold days in all seasons. However, this trend may be reversing in the past decade.