Variability of subduction rates of the subtropical North Pacific mode waters
Variability of subduction rates of the subtropical North Pacific mode waters
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DOI：
10.1007/s00343-011-0237-x
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发表时间：
2011-08
影响因子：
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通讯作者：
Haibo Hu;Qinyu Liu;Y. Zhang;Wei Liu
中科院分区：
文献类型：
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作者：
Haibo Hu;Qinyu Liu;Y. Zhang;Wei Liu
整个太平洋的气候学俯冲速率是已知的，但年际到年代际变化的机制仍不清楚。利用大气环流模式LICOM 1.0计算了1958-2001年北太平洋三种副热带模态沃茨的年俯冲率。模式试验的重点是在每日风强迫和季节热通量下海洋动力过程的年际变化。模式水的形成区域被定义为一个位涡最小露头位置。模拟结果表明，俯冲速率最大值（>100 m/a）分别位于副热带模态水（STMW）和中央模态水（CMW）形成区。这些区域与气候计算值一致。东副热带模态水（ESTMW）形成区的俯冲速率较小，约为75 m/a。俯冲速率显示出明显的年际和年代际变化与海洋动力学的变化。1981-1990年期间，STMW的平均俯冲速率较其他时期小得多，而CMW的平均俯冲速率在1975年之前为负异常，1978年之后为正异常。的变化同意Ekman和地转平流和混合层深度。在1970-1990年期间，ESTMW俯冲速率的年际变化最小，这是由于弱的风应力旋度。本文探讨了来自大气的年际信号是如何存储在海洋的不同部分，从而可能有助于更好地理解太平洋年代际振荡（PDO）事件的反馈机制。
The climatology subduction rate for the entire Pacific is known, but the mechanism of interannual to decadal variation remains unclear. In this study, we calculated the annual subduction rates of three types of North Pacific subtropical mode waters using a general circulation model (LICOM1.0) for the period of 1958–2001. The model experiments focused on interannual variations of ocean dynamical processes under daily wind forcings and seasonal heat fluxes. The mode water formation region was defined by a potential vorticity minimum at outcrop locations. The model results show that two subduction rate maxima (>100 m/a) were located in the Subtropical Mode Water (STMW) and the Central Mode Water (CMW) formation regions. These regions are consistent with a climatologically calculated value. The subduction rate in the Eastern Subtropical Mode Water (ESTMW) formation region was smaller at about 75 m/a. The subduction rate shows clear interannual and decadal variations associated with oceanic dynamic variabilities. The average subduction rate of the STMW was much smaller during the period of 1981–1990 compared with other periods, while that of the CMW had a negative anomaly before 1975 and a positive anomaly after 1978. The variability agreed with Ekman and geostrophic advections and mixed layer depths. The interannual variability of the subduction rate for the ESTMW was smallest during 1970–1990, as a result of a weak wind stress curl. This paper explores how interannual signals from the atmosphere are stored in different parts of the ocean, and thus may contribute to a better understanding of feedback mechanisms for the Pacific Decadal Oscillation (PDO) event.