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和最长的记录，但19世纪和世纪初的大部分潮汐记录（沿着潮汐站收集的天气数据）仍然没有数字化和使用。 在这个项目中，将开创一种新的方法来恢复、数字化、审查和分析来自俄勒冈州阿斯托里亚（1853-1876年）和加利福尼亚州圣地亚哥（1853-1872年）的世纪潮汐数据;这是三个最古老的太平洋潮汐记录中的两个。 这项工作的产品和相关的元数据恢复将被用来提高估计的19世纪平均海平面（MSL）在东北太平洋，评估潮汐特性的长期变化，并估计长期变化的风暴，例如，气候引起的，非潮汐的变化，发生由于风，河流流量，和其他过程。 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。 数据将得到改进（通过删除错误），已经恢复的阿斯托里亚和圣地亚哥的列表数据将通过从美国国家档案馆获得选定的海平面图（22米长的卷轴，每个卷轴包含一个月的铅笔潮汐跟踪）的数字副本来增加。 还将恢复元数据（水准和基准记录、时间检查和天气记录），并用于校正原始数据，将历史平均海平面与现代测量值进行比较。 一个新颖的方面是，恢复潮汐卷将数字化到6分钟的分辨率使用软件，而不是传统的缓慢和容易出错的手制表。 此外，创新的分析技术将用于发现和纠正错误。 使用校正的数据集，将评估和比较圣地亚哥、弗朗西斯科和阿斯托里亚的MSL变化。 在可能的范围内，将应用气压、河流流量和均衡反弹的校正。 分析将解决是否MSL在旧金山弗朗西斯科是美国西海岸的代表，并将通过与现代记录的比较，有助于限制MSL变化的长期趋势。 主要成分的长期变化（例如，M2）和浅水涨潮（例如，M4）将被评估。 频谱分析技术和在潮汐站收集的天气数据将用于调查旧金山弗朗西斯科水位信号非潮汐方差的长期变化。 由于涨潮是由水深测量，河流流量，分层和其他当地的过程，评估其随时间的变化可以提供洞察当地被迫改变河口的功能。 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。 更好地了解MSL和风暴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证明，这里要开发的方法可以在未来被用来恢复数百个站年的1850-1950年潮汐数据，目前存储在档案中的模拟形式（通常作为marigrams）。 PI是一个早期的职业科学家。