Climatology and interannual variability of arctic cyclone activity: 1948-2002
Climatology and interannual variability of arctic cyclone activity: 1948-2002
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DOI：
10.1175/1520-0442(2004)017
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发表时间：
2004-06-01
影响因子：
4.9
通讯作者：
Ikeda, M
中科院分区：
文献类型：
--
作者：
Zhang, XD;Walsh, JE;Ikeda, M
北极气旋活动的气候变化和变率的背景下进行了调查，使用修改后的自动气旋识别和跟踪算法，这不同于以前使用的算法，单一计数每个气旋。调查延长到55年（1948年至2002年）的时间周期延长到6小时的时间分辨率，通过记录的季节性和主导的时间模式的气旋活动的变化，并通过诊断区域活动量化的气旋活动指数（CAI）的早期研究。CAI将气旋强度、频率和持续时间的信息整合为气旋活动的综合指数。北极气旋活动在20世纪后半期有所增加，而中纬度的活动从1960年到1990年代初普遍减少，这与以前的研究结果一致。新的调查结果包括以下内容。1)从中纬度进入北极的气旋的数量和强度都有所增加，这表明风暴路径转移到北极，特别是在夏季。2)在1960-93年活动减少的时期之前和之后，中纬度气旋活动的积极趋势与北大西洋和欧亚板块气旋活动的变化密切相关。3)北冰洋（70 ° ~ 90 ° N）和北极边缘区（60 ° ~ 70 ° N）气旋活动的同步相位和振幅变化对决定整个北极气旋活动的变化起着关键作用。4)北极气旋活动显示出显著的低频变率，在1960年代有一个负相位，在1990年代有一个正相位，在此基础上叠加了7.8年和4.1年的振荡。7.8年的信号一般对应于北极海冰和海洋运动的气旋和反气旋制度的交替。
Arctic cyclone activity is investigated in the context of climate change and variability by using a modified automated cyclone identification and tracking algorithm, which differs from previously used algorithms by single counting each cyclone. The investigation extends earlier studies by lengthening the time period to 55 yr (1948-2002) with a 6-hourly time resolution, by documenting the seasonality and the dominant temporal modes of variability of cyclone activity, and by diagnosing regional activity as quantified by the cyclone activity index (CAI). The CAI integrates information on cyclone intensity, frequency, and duration into a comprehensive index of cyclone activity. Arctic cyclone activity has increased during the second half of the twentieth century, while midlatitude activity generally decreased from 1960 to the early 1990s, in agreement with previous studies. New findings include the following. 1) The number and intensity of cyclones entering the Arctic from the midlatitudes has increased, suggesting a shift of storm tracks into the Arctic, particularly in summer. 2) Positive tendencies of midlatitude cyclone activity before and after the 1960-93 period of decreasing activity correlate most strongly with variations of cyclone activity in the North Atlantic and Eurasian sectors. 3) Synchronized phase and amplitude variations in cyclone activity over the Arctic Ocean (70degrees-90degreesN) and the Arctic marginal zone (60degrees-70degreesN) play a critical role in determining the variations of cyclone activity in the Arctic as a whole. 4) Arctic cyclone activity displays significant low-frequency variability, with a negative phase in the 1960s and a positive phase in the 1990s, upon which 7.8- and 4.1-yr oscillations are superimposed. The 7.8- yr signal generally corresponds to the alternation of the cyclonic and anticyclonic regimes of the Arctic sea ice and ocean motions.