Characteristics of northern hemisphere blocking as determined from a long time series of observational data
Characteristics of northern hemisphere blocking as determined from a long time series of observational data
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DOI：
10.3402/tellusa.v35i5.11446
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发表时间：
1983-10
期刊：
影响因子：
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通讯作者：
H. Lejenäs;H. Økland
中科院分区：
文献类型：
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作者：
H. Lejenäs;H. Økland
30年观测500 mb位势高度数据已用于评估北半球阻塞情况的特征。定义适合识别阻塞的区域索引并将其转换为计算机程序。阻塞情况的特征已被计算并以统计数据的形式呈现。正如预期的那样，有 2 个首选封锁区域，大西洋区域和太平洋区域。结果表明，大西洋东部地区堵流天数最多，太平洋西部地区堵流天数最多。年度变化表明，大西洋地区从二月到四月有一个延长的最大值，而太平洋地区在一月有一个明显的最大值。还调查了两个区域同时发生阻塞的情况。结果表明，没有对连接的偏好。对个别阻塞情况的调查表明，最短的阻塞也是在优选的地理位置形成的，而不仅仅是西风带波浪模式变化中的随机配置。阻塞事件有一种趋势似乎集中在某些地理位置，事件的持续时间越长。研究结果还表明，大西洋地区的长期事件比太平洋地区更为频繁。 DOI：10.1111/j.1600-0870.1983.tb00210.x
30 years of observational 500 mb geopotential height data have been used to assess the characteristics of northern hemisphere blocking situations. A zonal index suitable for identification of blockings is defined and translated into a computer program. Characteristics of blocking situations have been computed and are presented as statistics. As expected, there are 2 preferred regions for blocking, the Atlantic region and the Pacific region. The results show that the number of days with blocked flow has a maximum over the eastern part of the Atlantic region, while the maximum is found over the western part of the Pacific region. The annual variation shows that there is an extended maximum from February through April in the Atlantic region, while there is a pronounced maximum in January in the Pacific region. The occurrence of simultaneous blocking in the 2 regions has also been investigated. The results show that there is no preference for a connection. Investigation of individual blocking situations reveals that the shortest ones are also formed in preferred geographical locations, and are not just random configurations in the changing pattern of waves in the Westerlies. There is a tendency for blocking episodes to seem to be concentrated in certain geographical locations, the longer the duration of the episode. The results also show that long-lasting episodes are notably more frequent in the Atlantic region than in the Pacific. DOI: 10.1111/j.1600-0870.1983.tb00210.x