A possible mechanism of solar modulation of the spatial structure of the North Atlantic Oscillation
A possible mechanism of solar modulation of the spatial structure of the North Atlantic Oscillation
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DOI：
10.1029/2004jd005258
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发表时间：
2005-01
影响因子：
--
通讯作者：
K. Kodera;Y. Kuroda
中科院分区：
文献类型：
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作者：
K. Kodera;Y. Kuroda
[1]冬季北大西洋涛动（NAO）的空间结构因太阳活动周期的不同而有显著差异。NAO在低太阳活动（LS）期间仅限于大西洋扇区，而在高太阳活动（HS）期间具有半球形结构。本研究的重点是确定所涉及的过程。分析结果表明，太阳活动的影响起源于平流层顶区，在那里，纬向平均纬向风的年际变化模式根据太阳活动而变化。在HS的初冬，主导的纬向风模态具有纬向偶极子型结构，通过与行星波的相互作用从平流层向下延伸到对流层。纬向风的偶极型异常在极区和周围地区之间的地面气压中产生半球尺度的跷跷板模式。因此，在HS期间的NAO具有半球形图案。在LS期间，纬向平均纬向风距平的向下延伸很弱，因此对流层的区域尺度变化占主导地位。
[1] The spatial structure of the North Atlantic Oscillation (NAO) in winter differs significantly according to the solar cycle. The NAO is confined to the Atlantic sector during low solar activity (LS), whereas it has a hemispherical structure during high solar activity (HS). The present study focuses on identifying the involved processes. The results of analyses suggest that the solar activity influence originates in the stratopause region, where the mode of interannual variation in the zonal-mean zonal winds changes according to solar activity. In the early winter of HS, the leading zonal wind mode has a meridional dipole-type structure that extends downward from the stratosphere to the troposphere through interaction with planetary waves. The dipole-type anomaly in the zonal winds produces a hemispherical scale seesaw pattern in the surface pressure between the polar region and surrounding regions. Thus the NAO during HS has a hemispherical pattern. During LS, the downward extension of zonal-mean zonal wind anomalies is weak, so the regional-scale variation becomes dominant in the troposphere.