NINETEENTH CENTURY US WEST COAST SEA LEVEL AND TIDAL PROPERTIES

潮汐数据是海洋中最古老和最长的记录，但19世纪和20世纪初的大部分潮汐记录(以及潮汐站收集的天气数据)仍然没有数字化，也没有被使用。在这个项目中，将开创恢复、数字化、审查和分析19世纪潮汐数据的新方法，这些潮汐数据来自美国阿斯托里亚(1853-1876)和加利福尼亚州圣地亚哥(1853-1872)；这是三个最古老的太平洋潮汐记录中的两个。这项工作和相关元数据恢复的产品将用于改进对19世纪东北太平洋平均海平面(MSL)的估计，评估潮汐特性的长期变化，并估计暴风雨的长期变化，例如，由于风、河流流动和其他过程而发生的气候引起的非潮汐变化。因此，该项目将解决当代重要的科学问题，如MSL的长期变化和加速、气候变化和当地变化的长期影响，以及旧数据的质量。数据将得到改进(通过消除错误)，已经为阿斯托里亚和圣地亚哥恢复的表格数据将通过从美国国家档案馆获得选定的金字塔(22米长的卷轴，每个卷轴包含一个月的铅笔潮汐痕迹)的数字副本来扩大。还将恢复元数据(水准测量和基准记录、时间校对和天气记录)，用于校正原始数据，并将历史平均海平面与现代测量结果进行比较。一个新颖的方面是，恢复的潮汐卷将使用软件数字化到6分钟的分辨率，而不是传统的缓慢和容易出错的手工制表。此外，将使用创新的分析技术来发现和纠正错误。使用校正后的数据集，将评估和比较圣地亚哥、旧金山和阿斯托里亚的MSL变化。在可能的范围内，将应用大气压力、河流流量和均衡反弹的修正。这项分析将解决旧金山的MSL是否代表美国西海岸的问题，并与现代记录相比，将有助于限制MSL变化的长期趋势。将评估主要成分(例如M2)和浅水潮汐(例如M4)的长期变化。频谱分析技术和潮汐观测站收集的天气数据将被用来调查旧金山水位信号中非潮汐变化的长期变化。由于涨潮是由水深测量、河流流动、分层和其他局部过程产生的，因此评估它们随时间的变化可以洞察局部强制改变河口功能的情况。在可能的范围内，局部变化、气候和河流强迫的影响将被分开。更广泛的影响：更好地了解MSL和暴风雨的变化有助于解决具有政策含义的重要当代科学问题。由于这项提议是一种概念验证，这里将要开发的方法将来可以用来恢复1850-1950年数百个站年的潮汐数据，这些数据目前以模拟形式(通常是金字塔)存储在档案中。私家侦探是一位早期的职业科学家。

Tidal data are the oldest and longest records available from the ocean, but much of the 19th and early 20th century tidal record (along with the weather data collected at tide stations) remains un-digitized and unused. In this project, novel ways of recovering, digitizing, vetting and analyzing 19th century tide data from Astoria, OR (1853-1876) and San Diego, CA (1853-1872) will be pioneered; these are two of the three oldest Pacific Ocean tidal records. The products of this work and related metadata recovery will be used to improve estimates of 19th century mean sea level (MSL) in the north-eastern Pacific, assess the secular change in tidal properties, and estimate long-term changes in storminess, for example, the climate induced, non-tidal variance that occurs due to wind, river flow, and other processes. This project will therefore address important contemporary scientific issues such as the long-term variation and acceleration in MSL, the long-term effects of climate change and local change, and the quality of old data. The data will be improved (by removing errors) and the tabulated data that has already been recovered for Astoria and San Diego will be augmented by obtaining digital copies of selected marigrams (22 m long scrolls that each contain one month of pencil tide tracings) from the US National Archive. Metadata (leveling and datum records, time checks and weather records), will also be recovered and used to correct the raw data and to compare historic mean sea-level with modern measurements. One novel aspect is that recovered tide rolls will be digitized to 6 minute resolution using software, rather than the traditional slow and error prone hand tabulations. Further, innovative analysis techniques will be used to find and correct errors. Using the corrected data sets, MSL variation from San Diego, San Francisco, and Astoria will be assessed and compared. To the extent possible, corrections for barometric pressure, river flow, and isostatic rebound will be applied. The analysis will address whether MSL at San Francisco is representative of the US West Coast, and will, by comparison with the modern record, help constrain long-term trends in MSL variation. Secular shifts in the primary constituents (e.g., M2) and the shallow-water overtides (e.g., M4) will be assessed. Spectral analysis techniques and weather data collected at tide stations will be used to investigate secular changes to the non-tidal variance in the water level signal for San Francisco. Because overtides are produced by bathymetry, river flow, stratification, and other local processes, assessing their change over time can provide insight into locally forced changes to the functioning of estuaries. To the extent possible, the effects of local changes, climate, and river forcing will be separated.Broader Impacts: A better understanding of changes to MSL and storminess helps address important contemporary scientific questions with policy implications. Because the proposal is a proof of concept, the methods to be developed here can in the future be used to recover hundreds of station-years of the 1850-1950 tide data that are currently stored in analog form (usually as marigrams) in archives. The PI is an early career scientist.