Intermediate Intraseasonal Variability in the Western Tropical Pacific Ocean: Meridional Distribution of Equatorial Rossby Waves Influenced by a Tilted Boundary
Intermediate Intraseasonal Variability in the Western Tropical Pacific Ocean: Meridional Distribution of Equatorial Rossby Waves Influenced by a Tilted Boundary
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热带西部太平洋的中间季节内变化：受倾斜边界影响的赤道罗斯贝波的经向分布
DOI：
10.1175/jpo-d-19-0184.1
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发表时间：
2020-03
影响因子：
3.5
通讯作者：
Shuwen Tan
中科院分区：
文献类型：
--
作者：
Zhixiang Zhang;Lawrence J. Pratt;Fan Wang;Jianing Wang;Shuwen Tan
用赤道Rossby波解释热带西太平洋7个次表层系泊的速度测量发现的20-90天的中深度季节内变率(ISV)。从2014年9月到2015年10月，这些系泊设备沿142°E部署在北纬0°到7.5°之间。在1200m处的ISV能量最强出现在4.5°N处，峰值能量在4.5°N处也出现在涡旋分辨全球环流模式中。对模式输出的分析表明，ISV的来源是赤道Rossby短波，相速向西，群速度向东南和向下。此外，还发现前三个斜压模的叠加才能表示ISV的能量传播。用1.5层浅水模式进行的进一步分析表明，第一经向Rossby波解释了西太平洋ISV的特殊经向分布。同样的模型表明，位于系泊地以南的Irian Jaya和巴布亚新几内亚倾斜的海岸线将经向速度振荡的北峰位置从3°N移动到近4.5°N。因此，需要考虑这一边界相对于纯纬向排列的倾斜，以解释峰值的经向移动。正压转换率的计算表明，1000m以下的季内动能可以输送到平均气流中，这可能是中深度纬向急流的强迫机制。
Abstract Intermediate-depth intraseasonal variability (ISV) at a 20–90-day period, as detected in velocity measurements from seven subsurface moorings in the tropical western Pacific, is interpreted in terms of equatorial Rossby waves. The moorings were deployed between 0° and 7.5°N along 142°E from September 2014 to October 2015. The strongest ISV energy at 1200 m occurs at 4.5°N. Peak energy at 4.5°N is also seen in an eddy-resolving global circulation model. An analysis of the model output identifies the source of the ISV as short equatorial Rossby waves with westward phase speed but southeastward and downward group velocity. Additionally, it is shown that a superposition of first three baroclinic modes is required to represent the ISV energy propagation. Further analysis using a 1.5-layer shallow water model suggests that the first meridional mode Rossby wave accounts for the specific meridional distribution of ISV in the western Pacific. The same model suggests that the tilted coastlines of Irian Jaya and Papua New Guinea, which lie to the south of the moorings, shift the location of the northern peak of meridional velocity oscillation from 3°N to near 4.5°N. The tilt of this boundary with respect to a purely zonal alignment therefore needs to be taken into account to explain this meridional shift of the peak. Calculation of the barotropic conversion rate indicates that the intraseasonal kinetic energy below 1000 m can be transferred into the mean flows, suggesting a possible forcing mechanism for intermediate-depth zonal jets.
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影响因子：
3.7
作者：
B. Hua;M. D'orgeville;M. Fruman;C. Ménesguen;R. Schopp;P. Klein;H. Sasaki
通讯作者：
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影响因子：
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通讯作者：
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