Variability and trends in the Southern Hemisphere high latitude, quasi-stationary planetary waves
Variability and trends in the Southern Hemisphere high latitude, quasi-stationary planetary waves
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南半球高纬度准静止行星波的变化和趋势
DOI：
10.1002/joc.4848
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Turner J
中科院分区：
文献类型：
--
作者：
Turner J
我们使用欧洲中期天气预报中心（ECMWF）中期再分析研究了1979-2013年南半球准定常行星波的变化和趋势。分析了热带和热带外强迫因子对行星波相位和振幅的影响。波数1-3的振幅表现出一个年周期，最小值在夏季，最大值在南半球的冬季。1号波的位相具有半年周期，春/秋季节向东移动，夏/冬季节向西移动，这是由于南大洋太平洋区半年振荡位相的差异造成的。3号波的位相有年周期，夏（冬）季偏东（向西）。1号波振幅的年际变化与阿蒙森海低压密切相关，而阿蒙森海低压又受到厄尔尼诺-南方涛动的强烈影响，因此1号波振幅在厄尔尼诺阶段的周期中较大。关于全年的趋势，自1979年以来，第1波的振幅有所下降（p < 0.1），而第2和第3波的振幅有所增加。这些变化与大部分热带海洋的海面温度变暖趋势一致。然而，与长期趋势有关的因素不如与年度间变化有关的因素那么清楚。
We investigate variability and trends of the Southern Hemisphere quasi-stationary planetary waves over 1979–2013 using the European Centre for Medium-range Weather Forecasts (ECMWF) Interim reanalyses. The effects of tropical and extra-tropical forcing factors on the phase and amplitude of the planetary waves are identified. The amplitudes of wave numbers 1–3 exhibit an annual cycle with a minimum in summer and maximum over the extended austral winter period. The phase of wave number 1 has a semi-annual cycle, moving east in austral spring/autumn and west in summer/winter as a result of differences in the phase of the semi-annual oscillation across the Pacific sector of the Southern Ocean. The phase of wave number 3 has an annual cycle, being more eastward (westward) in summer (winter). Year-to-year variability of the amplitude of wave number 1 is found to be strongly associated with the Amundsen Sea Low, which in turn is known to be strongly influenced by the El Niño–Southern Oscillation, with the consequence that the amplitude of wave number 1 is larger during the El Niño phase of the cycle. Regarding trends for the year as a whole, the amplitude of wave number 1 has decreased since 1979 (p < 0.1), while the amplitudes of wave numbers 2 and 3 have increased. These changes are consistent with the warming trends in sea surface temperatures across much of the tropical oceans. However, the factors associated with longer-term trends are less clear than for year-to-year variability.