Decadal variability of hydrography in the upper northern
Decadal variability of hydrography in the upper northern
复制标题
北部北部地区水文学的年代际变化
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
Y. Kushnir
中科院分区：
文献类型：
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作者：
G. Reverdin;D. Cayan;Y. Kushnir
我们调查的变化，北大西洋副北极环流在最近几十年的时间序列站的温度和盐度。年代际变率强的表面被确定，表现出垂直的连贯性比晚冬混合层更深的一层。在大西洋西北部，它对应于含有来自北冰洋或加拿大北极的水成分的层。研究了信号的空间相干性。滞后时间序列的经验正交函数分解表明，一个单一的模式解释了70%的上层海洋含盐量的方差，对应的传播信号从西到东北的副北极环流。最有可能的解释是，盐度信号起源于拉布拉多海的斜坡流，并扩散/平流向东的大银行在近西大西洋。在大西洋西北部，温度波动与盐度波动密切相关，并沿着平均T-S特征。这一信号表明，在斜坡流的淡水，冷水流出的大变化，并与冰盖密切相关。在55°N减弱的西风、格陵兰西部较弱的西北风和北大西洋中部和东部较弱的南风的流域尺度大气环流与第一主分量的高盐度和温水相有关。这种环流模式导致东北大西洋的波动，并滞后于盆地西北部的波动。风指数还表明，波动的淡水流出期间发生的异常偏北风的间隔，无论是东格陵兰岛（1965年，1968年至1969年）或关闭加拿大群岛（1983年至1984年）。
We investigate the variability of the North Atlantic subarctic gyre in recent decades from time series of station temperature and salinity. Decadal variability stronger at the surface is identified, which exhibits vertical coherence over a layer deeper than the late winter mixed layer. In the northwestern Atlantic, it corresponds to the layer with a component of water from the Arctic Ocean or from the Canadian Arctic. The spatial coherence of the signal is investigated. An empirical orthogonal function decomposition of lagged time series indicates that a single pattern explains 70% of the variance in upper ocean salt content, corresponding to a propagating signal from the west to the northeast in the subarctic gyre. The most likely interpretation is that the salinity signal originates in the slope currents of the Labrador Sea and is diffused/advected eastward of the Grand Banks over the near western Atlantic. In the northwestern Atlantic, temperature fluctuations are strongly correlated to salinity fluctuations and are aligned along the average T-S characteristics. This signal suggests large variations in the outflow of fresh, cold water in the slope current, and is strongly correlated with ice cover. A basin scale atmospheric circulation of weakened westerlies at 55°N, weaker northwesterlies west of Greenland and weaker southerlies over the central and eastern North Atlantic is associated with the high salinity and warm water phase of the first principal component. This circulation pattern leads fluctuations in the northeast Atlantic and lags those in the northwestern part of the basin. The wind indices also suggest that the fluctuations of the fresh water outflow occur during intervals of anomalously northerly winds, either east of Greenland (1965, 1968-1969) or off the Canadian Archipelago (1983-1984).