A comparison of recent and historical tides and mean sea-levels off Ireland
A comparison of recent and historical tides and mean sea-levels off Ireland
复制标题
爱尔兰近海潮汐和历史潮汐以及平均海平面的比较
DOI：
10.1111/j.1365-246x.1982.tb02799.x
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发表时间：
1982
影响因子：
2.8
通讯作者：
D. Pugh
中科院分区：
文献类型：
--
作者：
D. Pugh
潮汐和平均海平面条件对于沿海地貌、海洋沉积以及针对海洋洪水的保护屏障设计的重要性，研究了其感兴趣特征的任何长期趋势。不幸的是，高质量的海平面观测非常罕见;然而，在1842年夏天，在一次Orlando Survey水准测量作业期间，在爱尔兰海岸（Airy 1845）周围的22个地点进行了为期2个月的海平面同步观测（图1）。自1977年以来，我们在其中三个地点进行了为期一年的测量，即卡斯尔汤森、考顿和巴利卡斯尔。本报告比较了1842年调和潮汐分析的结果和最近的数据，以确定潮汐成分或平均水平是否有任何显着的变化。1842年的测量是从6月下旬到8月下旬在白天每隔5分钟通过阅读一次潮汐标杆进行的。除了白天的读数外，还通过夜间的高水位或低水位进行了几个小时的观测。时间受到严格控制，随后调整为格林威治时间。在每个地点建立了永久性的基准点，测量的水位参照这些基准点。原始数据现已存档在埃尔斯特蒙塞的皇家格林威治天文台的艾里收藏中。我们首先从中提取了一系列的每小时海平面，然后进行常规的谐波分析，从2个月的数据中提取27个成分，通过最小二乘拟合观测（Murray 1964），省略了没有数据记录的时期。在这些分析中，使用从最近数据年份获得的值，将无法通过短数据跨度分析分离的成分（如Sz和K）（需要6个月的数据进行分离）联系起来。现代数据进行了分析，作为一个单一的年度集，并作为一系列连续的29天块。从对这些区块的分析中获得的各个潮汐分量的变异性表明了从1842年的短期数据中获得的值的置信度。表1、2和3总结了这些分析结果。除了随机变化外，主要的月球半日分量M，显示出预期的轻微季节性调制（Pugh & Vassie 1976），夏季的振幅大于冬季。这些季节性调制的值分别为0.015，0.005和0.007米在Castletownsend，Courtown和Ballycastle。图2示出了比较
The importance of tidal and mean sea-level conditions for coastal geomorphology , marine sedimentation, and for the design of protective barriers against marine flooding, makes a study of any secular trends in their characteristics of interest. Unfortunately, high quality sea-level observations are very rare; however, during the summer of 1842, excellent simultaneous observations of sea-level were made for 2 months at 22 sites around the coast of Ireland (Airy 1845) during an Ordnance Survey levelling operation (Fig. 1). Since 1977 we have made measurements for a year at three of these sites, Castletownsend, Courtown and Ballycastle. This report compares the results of harmonic tidal analyses of the 1842 and the recent data, to determine whether there are any significant changes in the tidal constituents or in the mean levels. The 1842 measurements were made by reading tide poles at 5 minute intervals during daylight hours, from late June until late August. In addition to daylight readings, observations were also taken for a few hours through the night-time high or low water. Times were carefully controlled and subsequently adjusted to Greenwich time. Permanent bench marks were established at each site, and the measured levels were referred to these marks. The original data are now archived in the Airy collection at the Royal Greenwich Observatory, Herstmonceux. We first extracted series of hourly sea-levels from them, then made conventional harmonic analyses, extracting 27 constituents from the 2 months of data, by a least squares fit to the observations (Murray 1964), omitting the periods when no data were recorded. Constituents which could not be separated by analysis of the short data span, such as Sz and K,, which require 6 months of data for separation, were related in these analyses using the values obtained from the year of recent data. The modem data were analysed both as single annual sets, and as a series of consecutive 29 day blocks. The variability of the individual tidal constituents obtained from the analyses of these blocks gives an indication of the confidence to be given to the values obtained from the short period of 1842 data. Tables 1 , 2 and 3 summarize these analysis results. In addition to random variations, the principal lunar semi-diurnal constituent, M,, showed the expected slight seasonal modulation (Pugh & Vassie 1976), having a larger amplitude in the summer than during the winter. The values of these seasonal modulations were 0.015, 0.005 and 0.007 m at Castletownsend, Courtown and Ballycastle respectively. Fig. 2 shows a comparison