Comparing the steric height in the Nordic Seas with satellite altimeter sea surface height
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摘要: 利用水文数据EN3计算了北欧海的比容高度, 并将其异常与卫星高度计得到的海平面异常数据进行了比较。北欧海的平均比容高度呈现海盆中央低、沿岸高的分布状态。1993-2010年比容高度线性变化最大值分别位于罗弗敦海盆和挪威沿岸, 这一分布状态可能与北欧海的淡化趋势有关。海平面异常与比容高度异常的相关性空间分布不均。两者在罗弗敦海盆和挪威海盆北部相关性较好, 而在挪威海北部相关性较差, 这表明, 挪威海大部分海区受到斜压效应的控制, 而正压效应在挪威海北部占主导作用。海平面异常和比容高度异常在格陵兰海和冰岛海相关性较差表明这一区域正压贡献占优。北欧海区域平均的比容高度异常与海平面异常在1996-2002年振幅相近。除此之外, 比容高度异常的振幅总体低于海平面异常, 特别是在2006年以后, 前者对后者变化的解释不足50%。Abstract: In this study the steric height anomaly which is calculated from the hydrological data (EN3) is compared with the sea level anomaly derived from satellite altimetry in the Nordic Seas. The overall pattern of steric height is that it is higher in the margin area and lower in the middle area. The extreme values of steric height linear change from 1993 to 2010 occur in the Lofoten Basin and off the Norwegian coast, respectively. Such a distribution may be partly attributed to the freshening trend of the Nordic Seas. The correlation between SLA (sea level anomaly) and SHA (steric height anomaly) is not uniform over the Nordic Seas. The time series of SLA and SHA agree well in the Lofoten Basin and northern Norwegian Basin, and worse in the northern Norwegian Sea, implying that the baroclinic effect plays a dominant role in most areas in the Norwegian Sea and the barotropic effect plays a dominant role in the northern Norwegian Sea. The weaker correlations between SLA and SHA in the Greenland and Iceland Seas lead a conclusion that the barotropic contribution is significant in these areas. The area-mean SHA over the entire Nordic Seas has similar amplitudes compared with the SLA during 1996-2002, but SHA has become lower than SLA, being less than half of SLA since 2006.
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Key words:
- steric height /
- EN3 hydrological dataset /
- altimetric sea level anomaly /
- Nordic Seas
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