NINETEENTH CENTURY US WEST COAST SEA LEVEL AND TIDAL PROPERTIES

潮汐数据是海洋中最古老、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）仍未数字化，也未被使用。在这个项目中，将采用新颖的方法来恢复、数字化、审查和分析19世纪来自俄勒冈州阿斯托里亚（1853-1876）和加利福尼亚州圣地亚哥（1853-1872）的潮汐数据；这是三个最古老的太平洋潮汐记录中的两个。这项工作和相关的元数据恢复的产品将被用于提高19世纪的估计平均海平面(韩剧)在东北太平洋,评估世俗潮汐的变化特性,并估计长期猛烈的变化,例如,气候感应non-tidal方差发生由于风,河流量和其他流程。因此，该项目将解决重要的当代科学问题，如MSL的长期变化和加速，气候变化和局部变化的长期影响，以及旧数据的质量。这些数据将得到改进（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精选婚姻图（22米长的卷轴，每个卷轴包含一个月的铅笔潮汐图）的数字副本来增强。元数据（水平面和基准面记录、时间检查和天气记录）也将被恢复，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，回收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，创新的分析技术将用于发现和纠正错误。使用校正后的数据集，对圣地亚哥、旧金山和阿斯托里亚的MSL变化进行评估和比较。在可能的范围内，将应用对气压、河流流量和均衡回弹的校正。分析将解决旧金山的MSL是否代表美国西海岸，并将通过与现代记录的比较，帮助限制MSL变化的长期趋势。将评估主要成分（如M2）和浅水溢出（如M4）的长期变化。在潮汐站收集的光谱分析技术和天气数据将用于研究旧金山水位信号的非潮汐变化的长期变化。由于潮水是由水深测量、河流流量、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深入了解河口功能的局部强迫变化。在可能的范围内，局部变化、气候和河流强迫的影响将被分离。更广泛的影响：更好地了解MSL和风暴的变化有助于解决具有政策含义的重要当代科学问题。由于该建议是一个概念证明，因此在未来，这里开发的方法可以用于恢复目前以模拟形式（通常为婚姻图）存储在档案中的1850-1950年的数百个站年潮汐数据。PI是一个早期的职业科学家。

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.