Assessing variability in the size and strength of the North Atlantic subpolar gyre
Assessing variability in the size and strength of the North Atlantic subpolar gyre
复制标题
评估北大西洋副极地环流的大小和强度的变化
DOI：
10.1002/2017jc012798
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发表时间：
2017
影响因子：
--
通讯作者：
Susan Lozier
中科院分区：
文献类型：
--
作者：
N. Foukal;Susan Lozier
近期关于北大西洋亚极地环流（SPG）规模和强度的研究对该环流的时间变异性给出了截然不同的评估：利用卫星海面高度（SSH）的经验正交函数（EOF）分析的研究报告称，自1992年以来SPG的规模和强度迅速下降（约每十年20%），而同期的原位观测报告要么没有趋势，要么略有下降。在此，我们通过两种不同的方法分析1993年至2015年卫星SSH所反映的SPG的规模和强度来研究这种差异：通过EOF分析间接进行，以及更直接地通过对环流中心和边界的测量。我们将环流的边界定义为SSH的最大闭合等值线，中心定义为SSH最小值，强度定义为边界处与中心处SSH的差值。我们确定在研究期间SPG强度呈线性下降（每十年5.1%），但在SPG面积上未发现有统计学意义的趋势。环流强度的趋势比基于EOF的趋势要弱，且很可能低于原位测量的检测水平。我们得出结论，先前被确定为SPG环流急剧下降的变异性更适宜归因于卫星测高期间整个海盆的海平面上升。此外，我们发现SPG东部的特性与SPG的规模并非共同变化，这表明SPG的动力学并不控制环流间通量的强度。
Recent studies on the size and strength of the North Atlantic subpolar gyre (SPG) offer contrasting assessments of the gyre's temporal variability: studies that use empirical orthogonal function (EOF) analyses of satellite sea-surface height (SSH) report a rapid decline in SPG size and strength since 1992 (∼20% per decade), while concurrent in situ observations report either no trend or a slight decline. Here we investigate this discrepancy by analyzing the size and strength of the SPG with satellite SSH from 1993 to 2015 with two separate methods: indirectly via EOF analysis and more directly through measurements of the gyre center and boundary. We define the boundary of the gyre as the largest closed contour of SSH, the center as the minimum SSH, and the strength as the difference between the SSH at the boundary and the center. We identify a linear decline over the study period in the SPG strength (5.1% per decade), but find no statistically significant trend in the SPG area. The trend in the gyre strength is weaker than the EOF-based trend and is most likely below the level of detection of the in situ measurements. We conclude that the variability previously identified as a sharp decline in SPG circulation can be more appropriately attributed to basin-wide sea level rise during the satellite altimetry period. In addition, we find that the properties of the eastern SPG do not co-vary with the SPG size, suggesting that SPG dynamics do not control the strength of the inter-gyre throughput.
北大西洋海洋热异常的年代际演化：埃克曼、翻转和水平输送的影响
影响因子：
4.9
作者：
Roussenov V
通讯作者：
Roussenov V