On the importance of midlatitude oceanic frontal zones for the mean state and dominant variability in the tropospheric circulation
On the importance of midlatitude oceanic frontal zones for the mean state and dominant variability in the tropospheric circulation
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DOI：
10.1029/2008gl034010
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发表时间：
2008-08-13
影响因子：
5.2
通讯作者：
Xie, Shang-Ping
中科院分区：
文献类型：
--
作者：
Nakamura, Hisashi;Sampe, Takeaki;Xie, Shang-Ping
观测表明，中纬度天气系统在具有明显海表温度（SST）梯度的海洋锋区附近被组织成“风暴路径”。对规定海温纬向均匀分布的一对大气环流模式试验表明，它们观测到的配置不是偶然的。在一项实验中，风暴路径被锚定在中纬度海温锋附近，该锋维持近地表的热梯度并为涡旋提供能量。由涡旋输送的西风动量沿锋面产生了一个明确的极锋急流，即使在冬季副热带急流增强时也是如此。在另一个实验中，海温锋的移除导致涡旋活动和PFJ的显著减弱，特别是在冬季。这也导致了西风急流变率的主导模态——环空模的减弱和冬季明显的结构畸变。虽然是理想化的，但我们的实验表明，中纬度海洋锋对对流层环流及其变率的重要性。
Observations indicate that midlatitude weather systems are organized into "storm tracks'' near oceanic frontal zones with pronounced sea-surface temperature (SST) gradients. A pair of atmospheric general circulation model experiments with zonally uniform SST profiles prescribed show that their observed collocation is not fortuitous. In one experiment, a storm track is anchored around a midlatitude SST front that maintains near-surface thermal gradients and energizes eddies. Westerly momentum transport by eddies produces a well-defined polar-front jet along the front, even in winter when a subtropical jet stream intensifies. In the other experiment, removal of the SST front leads to a substantial weakening in eddy activity and the PFJ especially in winter. It also leads to a weakening of the annular mode-the dominant mode of westerly-jet variability-and its notable structural distortion in winter. Though idealized, our experiments suggest the importance of midlatitude oceanic fronts for the tropospheric circulation and its variability.