NINETEENTH CENTURY US WEST COAST SEA LEVEL AND TIDAL PROPERTIES

十九世纪美国西海岸海平面和潮汐特性

• 批准号: 1155610
• 负责人: Stefan Talke
• 金额: $ 9.38万
• 依托单位: Portland State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-03-01 至 2014-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1155610&HistoricalAwards=false
• 关键词: NINETEENTH; CENTURY; US; WEST; COAST

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.

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​​和未使用。 在该项目中，将开创恢复、数字化、审查和分析来自俄勒冈州阿斯托利亚（1853-1876）和加利福尼亚州圣地亚哥（1853-1872）的 19 世纪潮汐数据的新方法；这是太平洋最古老的三个潮汐记录中的两个。 这项工作的产品和相关元数据恢复将用于改进对东北太平洋 19 世纪平均海平面 (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，该项目将解决重要的当代科学问题，例如 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。 数据将得到改进（通过消除错误），并且通过从美国国家档案馆获取选定的 marigram（22 m 长的卷轴，每个卷轴包含一个月的铅笔潮汐追踪）的数字副本，将增强已恢复的阿斯托里亚和圣地亚哥的表格数据。 元数据（水准和基准记录、时间检查和天气记录）也将被恢复并用于纠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为 6 分钟分辨率，而不是传统的缓慢且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。 在可能的情况下，将应用气压、河流流量和等静压回弹的修正。 该分析将探讨旧金山的 MSL 是否代表美国西海岸，并将通过与现代记录进行比较，帮助限制 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。 光谱分析技术和潮汐站收集的天气数据将用于调查旧金山水位信号非潮汐变化的长期变化。 由于潮汐是由测深、河流流量、分层和其他当地过程产生的，因此评估其随时间的变化可以深入了解当地对河口功能的强制变化。 在可能的情况下，当地变化、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影响的重要当代科学问题。 由于该提案是一个概念验证，因此这里开发的方法将来可用于恢复 1850-1950 年数百个站年的潮汐数据，这些数据目前以模拟形式（通常为六角形）存储在档案中。 PI 是一位早期职业科学家。