Evolution and decay of a warm-core ring within the western subarctic gyre of the North Pacific, as observed by profiling floats
Evolution and decay of a warm-core ring within the western subarctic gyre of the North Pacific, as observed by profiling floats
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DOI：
10.1007/s10872-011-0027-2
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发表时间：
2011-04
影响因子：
2.3
通讯作者：
S. Itoh;Y. Shimizu;S. Ito;I. Yasuda
中科院分区：
文献类型：
--
作者：
S. Itoh;Y. Shimizu;S. Ito;I. Yasuda
这项研究调查了迁移到北太平洋副北极环流西部的暖心环的垂直结构和水特性的时间变化，其基础是对来自两个剖面浮标的温度和盐度数据的分析，以及船上和卫星观测数据。这些漂浮物最初于2003年9月被部署到寒冷和新鲜的Oyashio水中，并于2003年10月被夹带到一个温暖的核心环中，直到2004年12月才离开。急剧冷却和清新的上部核心水的环，观察到在上述夹带的浮子与冷水和淡水到环，而结构和水的性质的适度变化，观察在一个准孤立的阶段，从2003年11月至2004年11月，当环没有经历与环境水文特征的重大相互作用。在26.6σθ以上的相对暖盐水区，冬季受大气影响形成300 dB以上的深层混合层，春季至秋季在季节性密度跃层以下有明显的密度梯度。相比之下，较低的核心，与低于26.6σθ相对冷和淡水，在整个观察期间不通风。等密度面在准孤立阶段表现出约50分贝/年的变浅趋势，表明粘性衰减超过几年的时间尺度。在环内也经常观察到明显寒冷和粘稠的水，表明来自鄂霍次克海的水入侵。
This study investigated temporal variations in the vertical structure and water properties of a warm-core ring that migrated into the western subarctic gyre of the North Pacific, based on analyses of temperature and salinity data derived from two profiling floats, together with shipboard and satellite observation data. The floats were initially deployed into cold and fresh Oyashio water in September 2003, and were entrained into a warm-core ring in October 2003, remaining within the ring until detrainment in December 2004. Drastic cooling and freshening of the upper core water of the ring were observed during the above entrainment of the floats with cold and fresh water into the ring, whereas moderate variations in structure and water properties were observed during a quasi-isolated phase from November 2003 to November 2004 when the ring did not experience major interactions with ambient hydrographic features. The upper part of the core water (upper core), with relatively warm/saline water above 26.6σθ, was under the influence of the atmosphere in winter via the formation of a deep mixed layer exceeding 300 dB, and had a prominent pycnostad below the seasonal pycnocline from spring to autumn. In contrast, the lower core, with relatively cold and fresh water below 26.6σθ, was not ventilated throughout the observation period. Isopycnal surfaces showed a shoaling trend of about 50 dB/year during the quasi-isolated phase, suggesting viscous decay over a timescale of several years. Markedly cold and thick water was also frequently observed within the ring, indicating the intrusion of water from the Sea of Okhotsk.