Surface salinity variability in the northern North Atlantic during recent decades
Surface salinity variability in the northern North Atlantic during recent decades
复制标题
近几十年来北大西洋北部表面盐度变化
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
S. Häkkinen
中科院分区：
文献类型：
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作者：
S. Häkkinen
[1]基于综合大气海洋数据集（COADS）和国家环境预报中心/国家大气研究中心（NCEP/NCAR）再分析的大气强迫变率，利用数值模式模拟研究了北大西洋近50年来的海表盐度（SSS）变化。这里的重点是SSS的变化在副极地地区。副极地表层盐度变化的季节性是突出的最大标准差（SD）发生在夏季/秋季期间，使夏季SSS异常的幅度远远超过冬季。副极地环流SSS的年际变化主要是由于过量的冰融化，而长期（十年）的变化与纬向翻转的变化。在这两个后报，深混合（驱动翻转的变化）被迫热通量的变化，使弱的副极地热损失和随后的弱翻转通常表现在新鲜的表面条件下，在副极地环流在2年内。这是因为深对流的作用是混合高纬度地区接收的净淡水输入。因此，在缺乏广泛的深层混合的情况下，这是一个减缓翻转的信号，根据气候学预计的淡水输入将在表面积累。
[1] The sea surface salinity (SSS) variability in the North Atlantic is investigated using numerical model simulations for the last 50 years based on atmospheric forcing variability from the Comprehensive Atmosphere Ocean Data Set (COADS) and National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis. The focus here is the SSS variability in the subpolar region. The seasonality of the subpolar surface salinity variability is prominent with the maximum standard deviation (SD) occurring in the summer/fall period so that the amplitude of the summer SSS anomalies far exceed those of the wintertime. The interannual SSS variability in the subpolar gyre can be attributed mainly to excess ice melt, while the longer-term (decadal) variability is associated with meridional overturning variability. In these two hindcasts, the deep mixing (which drives overturning changes) is forced by heat flux variability so that weak subpolar heat loss and subsequent weak overturning are usually manifested in fresh surface conditions in the subpolar gyre within 2 years. This is because the role of deep convection is to mix down the net fresh water input received by the high latitudes. Hence, at the lack of widespread deep mixing, a signal of slowing down overturning, the fresh water input that would be expected based on climatology would accumulate at the surface.