The data set comprises time series of sea level data from coastal tide gauges. The data holdings include over 1000 site years of data from about 200 sites comprising about 10 million records. About 75 per cent of the data are from some 100 sites around the British Isles - the remaining data are from coastal sites and islands scattered across the globe. Data are primarily hourly values. Recording periods vary from one month at some sites to over several years.There are three short series from around the Irish coast which were collected in 1842.

This dataset contains high and low water values manually digitised from historic hand-written tabulated ledgers, from the Port of London Authority (PLA). The dataset contains 463 years of data, from across 15 tide gauge sites along the Thames Estuary (bounding box = -0.3159W, 51.3914N, 1.3797E, 51.8428N), for the period 1911 to 1995. When these historic records are combined with digital records available from the PLA since 1995, the new sea level time-series spans the 109-year period from 1911 to 2019. London is one of the world’s most important coastal cities and is located around the Thames Estuary. Quantifying changes in sea levels in the Thames Estuary over the 20th century and early part of the 21st century is vital to inform future management of flood risk in London. This dataset is of importance for ongoing monitoring of mean sea-level rise, and changes in tidal range and extreme sea levels in the Thames Estuary. The project was led by the Ocean and Earth Science, University of Southampton and the Environment Agency, with contributions from the Leibniz Institute for Baltic Sea Research Warnemunde and the National Oceanography Centre. The study contributes to the objectives of UK National Environment Research Council (NERC) project E-Rise: Earliest detection of sea-level rise accelerations to inform lead time to upgrade/replace coastal flood defence infrastructure (NE/P009069/1; I.D.H.).

This database, and the accompanying website called ‘SurgeWatch’ (http://surgewatch.stg.rlp.io), provides a systematic UK-wide record of high sea level and coastal flood events over the last 100 years (1915-2014). Derived using records from the National Tide Gauge Network, a dataset of exceedence probabilities from the Environment Agency and meteorological fields from the 20th Century Reanalysis, the database captures information of 96 storm events that generated the highest sea levels around the UK since 1915. For each event, the database contains information about: (1) the storm that generated that event; (2) the sea levels recorded around the UK during the event; and (3) the occurrence and severity of coastal flooding as consequence of the event. The data are presented to be easily assessable and understandable to a wide range of interested parties. The database contains 100 files; four CSV files and 96 PDF files. Two CSV files contain the meteorological and sea level data for each of the 96 events. A third file contains the list of the top 20 largest skew surges at each of the 40 study tide gauge site. In the file containing the sea level and skew surge data, the tide gauge sites are numbered 1 to 40. A fourth accompanying CSV file lists, for reference, the site name and location (longitude and latitude). A description of the parameters in each of the four CSV files is given in the table below. There are also 96 separate PDF files containing the event commentaries. For each event these contain a concise narrative of the meteorological and sea level conditions experienced during the event, and a succinct description of the evidence available in support of coastal flooding, with a brief account of the recorded consequences to people and property. In addition, these contain graphical representation of the storm track and mean sea level pressure and wind fields at the time of maximum high water, the return period and skew surge magnitudes at sites around the UK, and a table of the date and time, offset return period, water level, predicted tide and skew surge for each site where the 1 in 5 year threshold was reached or exceeded for each event. A detailed description of how the database was created is given in Haigh et al. (2015). Coastal flooding caused by extreme sea levels can be devastating, with long-lasting and diverse consequences. The UK has a long history of severe coastal flooding. The recent 2013-14 winter in particular, produced a sequence of some of the worst coastal flooding the UK has experienced in the last 100 years. At present 2.5 million properties and £150 billion of assets are potentially exposed to coastal flooding. Yet despite these concerns, there is no formal, national framework in the UK to record flood severity and consequences and thus benefit an understanding of coastal flooding mechanisms and consequences. Without a systematic record of flood events, assessment of coastal flooding around the UK coast is limited. The database was created at the School of Ocean and Earth Science, National Oceanography Centre, University of Southampton with help from the Faculty of Engineering and the Environment, University of Southampton, the National Oceanography Centre and the British Oceanographic Data Centre. Collation of the database and the development of the website was funded through a Natural Environment Research Council (NERC) impact acceleration grant. The database contributes to the objectives of UK Engineering and Physical Sciences Research Council (EPSRC) consortium project FLOOD Memory (EP/K013513/1).

This dataset contains tabulations of the heights and times of tidal high and low water at St. Helena from 1 October 1826 to 31 October 1827. The tide was recorded by an instrument designed by Manuel Johnson, a future President of the Royal Astronomical Society, while waiting for an observatory to be built. The tabulations in this dataset were obtained by inspection of photographs of Johnson's tabulation sheets that are held in the archive RGO 6/500 in the Royal Greenwich Observatory collection at Cambridge University Library. It is an important record in the history of tidal science, as the only previous measurements at St. Helena had been those made by Nevil Maskelyne in 1761, and there were to be no other systematic measurements until the late 20th century. Johnson’s tide gauge, of a curious but unique design, recorded efficiently the height of every tidal high and low water for at least 13 months, in spite of requiring frequent re-setting. These heights compare very reasonably with a modern tidal synthesis based on present-day tide gauge measurements from the same site. Johnson’s method of timing is unknown, but his calculations of lunar phases suggest that his tidal measurements were recorded in Local Apparent Time. Unfortunately, the recorded times are found to be seriously and variably lagged by many minutes. Johnson’s data have never been fully published, but his manuscripts have been safely archived and are available for inspection at Cambridge University. His data have been converted to computer files as part of this study for the benefit of future researchers. This dataset supports the paper “Cartwright, D.E.; Woodworth, P.L.; Ray, R.D.. 2017 Manuel Johnson's tide record at St. Helena. History of Geo- and Space Sciences”. Richard Ray (National Aeronautics and Space Administration) and Philip Woodworth (National Oceanography Centre) modified and added figures to David E. Cartwright’s original draft paper and sections of text have been updated, but otherwise the paper is as he intended it. This work was undertaken when Philip Woodworth was an Honorary Research Fellow at the National Oceanography Centre in Liverpool in receipt of an Emeritus Fellowship from the Leverhulme Trust. Part of this work was funded by UK Natural Environment Research Council National Capability funding.

A large number of charts (originals and copies) together with tabulations of data are also available, some of which date back to the 1850s. A more detailed description of these will be available once they have been systematically catalogued and archived.

Historical sea level data for the Thames region. These data were originally screened as part of an Environment Agency project on extreme sea level in the Thames estuary. Coryton: 1966-1970, 1973-1974 North Woolwich: 1950, 1955-1963, 1965-1967, 1969-1970, 1973-1974 Southend: 1981-1983 Tilbury: 1931-1945, 1960-1961, 1967, 1970, 1984 Tower Pier: 1928-1942, 1944-1945, 1947-1951, 1954-1955, 1958, 1960-1966, 1973

The dataset contains 39148 years of sea level data from 1355 station records, with some stations having alternative versions of the records provided from different sources. GESLA-2 data may be obtained from www.gesla.org. The site also contains the file format description and other information. The text files contain headers with lines of metadata followed by the data itself in a simple column format. All the tide gauge data in GESLA-2 have hourly or more frequent sampling. The basic data from the US National Atmospheric and Oceanic Administration (NOAA) are 6-minute values but for GESLA-2 purposes we instead settled on their readily-available 'verified hourly values'. Most UK records are also hourly values up to the 1990s, and 15-minute values thereafter. Records from some other sources may have different sampling, and records should be inspected individually if sampling considerations are considered critical to an analysis. The GESLA-2 dataset has global coverage and better geographical coverage that the GESLA-1 with stations in new regions (defined by stations in the new dataset located more than 50 km from any station in GESLA-1). For example, major improvements can be seen to have been made for the Mediterranean and Baltic Seas, Japan, New Zealand and the African coastline south of the Equator. The earliest measurements are from Brest, France (04/01/1846) and the latest from Cuxhaven, Germany and Esbjerg, Denmark (01/05/2015). There are 29 years in an average record, although the actual number of years varies from only 1 at short-lived sites, to 167 in the case of Brest, France. Most of the measurements in GESLA-2 were made during the second half of the twentieth century. The most globally-representative analyses of sea level variability with GESLA-2 will be those that focus on the period since about 1970. Historically, delayed-mode data comprised spot values of sea level every hour, obtained from inspection of the ink trace on a tide gauge chart. Nowadays tide gauge data loggers provide data electronically. Data can be either spot values, integrated (averaged) values over specified periods (e.g. 6 minutes), or integrated over a specified period within a longer sampling period (e.g. averaged over 3 minutes every 6 minutes). The construction of this dataset is fundamental to research in sea level variability and also to practical aspects of coastal engineering. One component is concerned with encouraging countries to install tide gauges at locations where none exist, to operate them to internationally agreed standards, and to make the data available to interested users. A second component is concerned with the collection of data from the global set of tide gauges, whether gauges have originated through the GLOSS programme or not, and to make the data available. The records in GESLA-2 will have had some form of quality control undertaken by the data providers. However, the extent to which that control will have been undertaken will inevitably vary between providers and with time. In most cases, no further quality control has been made beyond that already undertaken by the data providers. Although there are many individual contributions, over a quarter of the station-years are provided by the research quality dataset of UHSLC. Contributors include: British Oceanographic Data Centre; University of Hawaii Sea Level Center; Japan Meteorological Agency; US National Oceanic and Atmospheric Administration; Puertos del Estado, Spain; Marine Environmental Data Service, Canada; Instituto Espanol de Oceanografica, Spain; idromare, Italy; Swedish Meteorological and Hydrological Institute; Federal Maritime and Hydrographic Agency, Germany; Finnish Meteorological Institute; Service hydrographique et oc?anographique de la Marine, France; Rijkswaterstaat, Netherlands; Danish Meteorological Institute; Norwegian Hydrographic Service; Icelandic Coastguard Service; Istituto Talassographico di Trieste; Venice Commune, Italy;

The dataset consists of 2580 tiff images of tide gauge charts from Bowling, River Clyde. The images were taken from annual bound volumes of tide gauge charts (~1 page per week, 52 pages per volume). A typical volume measures 37 x 34 x 3.5 cm and pages are single sided. The ledgers for Bowling begin in 1888 and end in 1952, but under this project, only the charts up until 04/01/1939 were photographed. The trace on the original charts was generated by a float tide gauge. The float inside a stilling-well was connected by a wire run over pulleys to a pen that moved up and down as the tide rose and fell. The images were generated by a commercial scanning organisation (TownsWeb Archiving Ltd) using a planetary overhead book scanner. In July 2016 The Peel Group Ltd. (Glasgow) approached BODC to donate their tidal archive, due to office redevelopment. The archive consists of ledgers of tide gauge charts (345 annual bound volumes) and handwritten ledgers (91 bound books) from several locations along the Clyde, with the earliest record beginning in 1841 from Glasgow Harbour. Later that year BODC received a grant from the Marine Environmental Data and Information Network (MEDIN) to photograph a selection of the ledgers. MEDIN released these funds to support small Data Archiving Projects that increase access to industry marine data. Ledgers also exist for Broomielaw, Dalmuir, Gourock, Govan Wharf, Greenock, Partick Wharf Glasgow, Queen's Dock Entrance Glasgow and Rothesay Dock. Most begin in the late 19th Century and run to the mid-20th century. It is hoped that these will be digitised in the future, subject to funding.

The UK national network of sea level gauges was established after violent storms in the North Sea in 1953 resulted in serious flooding in the Thames Estuary. The data are required for research and operational use and to facilitate specific scientific studies of coastal processes such as tidal response, storm surge behaviour and sea level rise; and for underpinning local and national operational systems such as the Storm Tide Forecasting Service at the Met Office. BODC has a special responsibility for the remote monitoring and retrieval of sea level data from the network. Daily checks are kept on the performance of the gauges and the data are downloaded weekly. These are then routinely processed and quality controlled prior to being made available.