Divergent Eddy Heat Fluxes in the Kuroshio Extension at 144°–148°E. Part II: Spatiotemporal Variability
Divergent Eddy Heat Fluxes in the Kuroshio Extension at 144°–148°E. Part II: Spatiotemporal Variability
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DOI：
10.1175/jpo-d-13-061.1
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发表时间：
2013-11
影响因子：
3.5
通讯作者：
S. Bishop
中科院分区：
文献类型：
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作者：
S. Bishop
黑潮扩展系统研究（KESS）提供了16个月的观测，以量化从一个中尺度分辨阵列的电流和压力装备的倒置回声测深仪的发散涡动热通量（DEHF）。KESS观测捕捉到了从稳定状态到不稳定状态的转变。两种制度下的DEHF的空间结构存在明显差异。稳定的制度有弱的下降梯度的DEHF。不稳定的制度表现出不对称沿着的平均路径与强大的下行梯度DEHF上游的平均槽在; 1478 E。台风的空间结构是由中尺度过程引起的。前6个月处于稳定状态，其中通量与向东传播的10 - 15天上游河曲有关。6个月后，黑潮延伸体经历了一个由稳定状态向不稳定状态的转变。这种制度的转变对应的红移中尺度现象的患病率;40天深外部产生的漩涡。DEHF振幅超过四倍，在不稳定的制度。冷芯环（CCR）的形成，CCR-喷流的相互作用，以及之间的耦合;40天的深涡是负责在平均图中的不对称的下降梯度通量在稳定的制度。黑潮延伸区具有与外部产生的涡旋相关的显著的深层能量，这些涡旋与喷流相互作用以驱动一些最大的DEHF事件。这些涡流通过涡流-平均流相互作用在射流的可变性中起着重要作用。垂直耦合产生的DEHF与斜压不稳定一致。这种相互作用不是从微扰开始的，而是从一开始就是一种有限振幅的相互作用。
The Kuroshio Extension System Study (KESS) provided 16 months of observations to quantify divergent eddy heat flux (DEHF) from a mesoscale-resolving array of current- and pressure-equipped inverted echo sounders. KESS observations captured a regime shift from a stable to unstable state. There is a distinct difference in the spatial structure of DEHFs between the two regimes. The stable regime had weak downgradient DEHFs. The unstable regime exhibited asymmetry along the mean path with strong downgradient DEHFs upstream of a mean trough at ;1478E. The spatial structure of DEHFs resulted from episodic mesoscale processes. The first 6 months were during the stable regime in which fluxes were associated with eastward-propagating 10‐15-day upper meanders. After 6 months, the Kuroshio Extension underwent a regime shift from a stable to unstable state. This regime shift corresponded with a red shift in mesoscale phenomena with the prevalence of ;40-day deep externally generated eddies. DEHF amplitudes more than quadrupled during the unstable regime. Cold-core ring (CCR) formation, CCR‐jet interaction, and coupling between ;40-day deep eddies were responsible for asymmetry in downgradient fluxes in the mean maps not observed during the stable regime. The Kuroshio Extension has prominent deep energy associated with externally generated eddies that interact with the jet to drive some of the biggest DEHF events. These eddies play an important role in the variability of the jet through eddy‐mean flow interactions. The DEHFs that result from vertical coupling act in accordance with baroclinic instability. The interaction is not growth from an infinitesimal perturbation, but from the start is a finite-amplitude interaction.