Comparisons of sea level and bottom pressure measurements at Drake Passage
Comparisons of sea level and bottom pressure measurements at Drake Passage
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德雷克海峡海平面和底部压力测量结果的比较
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发表时间：
1988
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通讯作者：
R. Peterson
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文献类型：
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作者：
R. Peterson
将德雷克海峡两侧的验潮仪和海平面气压测量值与500米深处的海底压力多年时间序列进行了比较。由英国南极调查局法拉第基地的潮汐和海平面气压记录得出的经40小时低通滤波器平滑的合成次表层压力（SSP），在6到600天的周期内与德雷克海峡南部的海底压力具有相干性，但在年周期上约有60°的相位差。对于长于60天的周期，这两个序列之间的差异主要是年际的，并且与海底压力本身的季节性变化一样大或更大。南极洲附近开阔海洋混合层密度的年际变化太小，无法解释这种差异。法拉第的SSP序列跨度为21年，略长于18.6年的月球交点潮，后者似乎存在于记录中。在德雷克海峡北侧，来自智利威廉姆斯港的SSP在任何周期段都与附近的海底压力不太匹配，这显然是由于100天以下周期的局地风以及上层密度的年周期所致。即使在季节周期内，南极绕极流输运的正压变化比由于上层密度变化引起的斜压变化大一个数量级，但利用这些海面观测也无法直接估算正压变化。
Tide gauge and atmospheric sea level pressure measurements from each side of Drake Passage are compared with multiyear time series of bottom pressure at 500 m depth. Synthetic subsurface pressure (SSP), smoothed with a 40-hour low-pass filter, derived from tidal and sea level pressure records from the British Antarctic Survey base Faraday is coherent with bottom pressure from southern Drake Passage for periods of 6 to 600 days, but it is about 60° out-of-phase at the annual period. The difference between the two series for periods longer than 60 days is mainly annual and is as large as, or larger than, the seasonal variability of bottom pressure itself. Annual variations in open ocean mixed-layer density near Antarctica are too small to account for the difference. The Faraday SSP series spans 21 years, slightly longer than the 18.6-year lunar nodal tide, which appears to exist in the record. At the northern side of Drake Passage, SSP from Puerto Williams, Chile, does not compare well with nearby bottom pressure for any band of periods, apparently due to local winds for periods under 100 days and to annual cycles in upper layer density. Barotropic changes in transport of the Antarctic Circumpolar Current cannot be directly estimated using these surface observations, even though over seasonal periods they are an order of magnitude larger than the baroclinic changes due to variations in upper layer density.