View source for Newlyn Tidal Observatory

{{Short description|British tidal observatory}}
{{Infobox building
| name                = Newlyn Tidal Observatory
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| image               = Newlyn harbour light 342.jpg
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| image_caption       = View of Newlyn Harbour with the lighthouse and Tidal Observatory to its right
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| alternate_names     = [[Earth:Global Sea Level Observing System|GLOSS]] ID 241
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| building_type       = [[Earth:Tide gauge|tide gauge]]
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| location            = Newlyn
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| location_country    = United Kingdom
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| opened_date         = 1915
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| operator            = [[Organization:National Oceanography Centre|National Oceanography Centre]]<ref name="NOC">{{cite web |title=Newlyn |url=https://psmsl.org/data/obtaining/stations/202.php |website=[[Organization:National Oceanography Centre|National Oceanography Centre]] |access-date=3 October 2023 |archive-date=3 October 2023 |archive-url=https://web.archive.org/web/20231003203237/https://psmsl.org/data/obtaining/stations/202.php |url-status=live}}</ref>
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| known_for           = [[Ordnance datum|Ordnance Datum Newlyn]]
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'''Newlyn Tidal Observatory''' is a grade II listed [[Earth:Tide gauge|tide gauge]] hut on the South Pier in Newlyn, Cornwall in England. Measurements of sea level taken at the observatory between 1915 and 1921 were used to define the reference level, Ordnance Datum Newlyn, for height measurement on the British mainland. The tide gauge has collected over 100 years of observations which has significantly contributed to studies in [[Sea level|sea level]] science.

==Building and location==
The observatory is a building situated behind the lighthouse at the end of the South Pier in Newlyn, near Penzance, in Cornwall. Constructed of concrete, it has the appearance of a small hut and is painted in red and white stripes.<ref name="bbc"/> Inside the building is an Ordnance Survey [[Benchmark (surveying)|benchmark]], constituted of a brass bolt (OSBM SW 4676 2855), and a {{convert|1.6|m|adj=on}} diameter stilling well set into the pier which has ocean access via an inlet.<ref name ="MG"/><ref>{{cite web |title=Newlyn Tidal Observatory |url=http://www.pol.ac.uk/ntslf/tgi/ntobs.html |website=[[Organization:Proudman Oceanographic Laboratory|Proudman Oceanographic Laboratory]] |archive-url=https://web.archive.org/web/20050414145457/http://www.pol.ac.uk/ntslf/tgi/ntobs.html |archive-date=14 April 2005}}</ref><ref>{{cite web |title=NEWLYN |url=https://psmsl.org/data/obtaining/stations/202.php |website=Permanent Service for Mean Sea Level |access-date=8 November 2023 |quote=Documentation added 1991-06-11 Newlyn 170/161 RLR(1964) is 11.7m below TGBM SW4676 2855 |archive-date=3 October 2023 |archive-url=https://web.archive.org/web/20231003203237/https://psmsl.org/data/obtaining/stations/202.php |url-status=live}}</ref>

==History==
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| caption = The observatory building in 2011
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The [[Earth:Ordnance Survey|Ordnance Survey]] established the observatory in 1915 to contribute to the measurement of a national [[Vertical datum|vertical datum]] defined by mean sea level. The subsequent 6-year measurement campaign at the observatory, conducted from 1 May 1915 to 30 April 1921, determined the value of mean sea level as {{cvt|4.751|m}} below the level of the brass bolt benchmark inside the hut. Due to the stable underlying granite bedrock, the proximity to the open ocean, and the absence of rivers, the observations at Newlyn were selected as the basis, or [[Ordnance datum|ordnance datum]], for elevation measurements across Great Britain. To realise the reference [[Vertical datum|datum]] across the country, in the early twentieth century spirit [[Levelling|levelling]] techniques were used to measure a national network of circa 200 fundamental benchmarks, all referenced to the Newlyn brass bolt.<ref name="bbc">{{cite news |last1=Amos |first1=Jonathan |title=The Cornish hut that gave rise to sea level benchmark |url=https://www.bbc.co.uk/news/science-environment-56935097 |access-date=3 October 2023 |work=BBC |date=30 April 2021 |archive-date=3 October 2023 |archive-url=https://web.archive.org/web/20231003203242/https://www.bbc.co.uk/news/science-environment-56935097 |url-status=live}}</ref><ref name ="MG">{{cite journal |title=A Century of Sea Level Measurements at Newlyn, Southwest England |journal=[[Earth:Marine Geodesy|Marine Geodesy]] |date=18 March 2016 |doi=10.1080/01490419.2015.1121175 |last1=Bradshaw |first1=E. |last2=Woodworth |first2=P.L. |last3=Hibbert |first3=A. |last4=Bradley |first4=L.J. |last5=Pugh |first5=D.T. |last6=Fane |first6=C. |last7=Bingley |first7=R.M. |volume=39 |issue=2 |pages=115–140 |bibcode=2016MarGe..39..115B |s2cid=131242174 |doi-access=free}}</ref><ref name="guide">{{cite web |title=A Guide to Coordinate Systems in Great Britain |url=https://www.ordnancesurvey.co.uk/documents/resources/guide-coordinate-systems-great-britain.pdf |website=[[Earth:Ordnance Survey|Ordnance Survey]] |access-date=3 October 2023 |pages=15–16 |archive-date=24 September 2015 |archive-url=https://web.archive.org/web/20150924061607/http://www.ordnancesurvey.co.uk/docs/support/guide-coordinate-systems-great-britain.pdf |url-status=live}}</ref><ref name="NG"/>

From 1915 to 1983 the observatory measured sea level using a float in the stilling well, along with a gauge supplied by [[Company:William Cary (instrument maker)|Cary and Porter]]. With advances in technology, an Aanderaa pressure gauge was installed in 1981 to operate alongside the well gauge. Since 1983 the primary sensor has been a bubbler pressure gauge.<ref name ="MG"/><ref>{{cite web |title=Station information |url=https://gloss-sealevel.org/gloss-station-handbook |website=[[Earth:Global Sea Level Observing System|Global Sea Level Observing System]] |quote=1915 – 1984 Float/stilling well 1983 – Bubbler gauge |access-date=3 October 2023 |archive-date=28 May 2023 |archive-url=https://web.archive.org/web/20230528233912/https://gloss-sealevel.org/gloss-station-handbook |url-status=live}}</ref> 

The Ordnance Survey operated the tide gauge until 1983, when the Natural Environment Research Council took over the management.<ref name ="MG"/> The observatory was designated as grade II listed status by Historic England in December 2018.<ref>{{cite web |title=Newlyn tidal observatory and part of the south pier |url=https://historicengland.org.uk/listing/the-list/list-entry/1460225 |website=Historic England |access-date=3 October 2023 |archive-date=3 October 2023 |archive-url=https://web.archive.org/web/20231003203242/https://historicengland.org.uk/listing/the-list/list-entry/1460225 |url-status=live}}</ref> As of 2023 the observatory is operated by the [[Organization:National Oceanography Centre|National Oceanography Centre]], and funding support is contributed by the UK Environment Agency.<ref name="NOC"/><ref name ="MG"/>

==Impact==
[[File:Newlyn Monthly Mean Sea Level 1915 - 2023 (m).png|thumb|right|260px|Time series plot of monthly Mean Sea Level at Newlyn, Cornwall, 1915 to 2023]]
The 6 years of observations captured at the observatory up to 1921 continue to define the height reference system for Great Britain, with varied applications including flood planning, understanding air pollution, infrastructure design, and deliveries by unmanned aerial vehicles.<ref name ="bbc"/> 

In 2016 Bradshaw et al. published an article to commemorate 100 years of sea level measurements at the Newlyn observatory, in particular highlighting how the collected data had "played a fundamental role in UK geodesy and oceanography",<ref name ="MG"/> and in 2021 the impact of the data on ocean and climate change studies was noted.<ref name="NG">{{cite news |last1=Manning |first1=Jonathan |title=A century ago, scientists in this remote Cornish hut established height zero. Here's why it matters. |url=https://www.nationalgeographic.co.uk/science-and-technology/2021/08/a-century-ago-scientists-in-this-remote-cornish-hut-established-height-zero-heres-why-it-matters |access-date=3 October 2023 |work=National Geographic |date=25 August 2021 |quote=While ODN has proved a priceless reference point for land heights in Britain, it is plays a key role in ocean studies, too |archive-date=3 October 2023 |archive-url=https://web.archive.org/web/20231003203242/https://www.nationalgeographic.co.uk/science-and-technology/2021/08/a-century-ago-scientists-in-this-remote-cornish-hut-established-height-zero-heres-why-it-matters |url-status=live}}</ref><ref>{{cite news |last1=Simons |first1=Paul |title=Newlyn pier plays a crucial role in understanding climate change |url=https://www.thetimes.co.uk/article/weather-eye-sat-1-may-tqvjfhr7h |work=The Times |date=1 May 2021 |access-date=3 October 2023 |archive-date=3 October 2023 |archive-url=https://web.archive.org/web/20231003205434/https://www.thetimes.co.uk/article/weather-eye-sat-1-may-tqvjfhr7h |url-status=live}}</ref>

==See also==
* {{Annotated link | Ordnance Survey National Grid}}
* {{Annotated link | Principal Triangulation of Great Britain}}
* {{Annotated link | Chart datum}}

==References==
{{Reflist}}

==Further reading==
* Cockram R., L. Holmes, R. Hogg and F. Iddiols. "The Newlyn Tidal Observatory." (2018) {{ISBN|978-0-9567528-4-0}}

[[Category:Geodetic surveys]]
[[Category:Vertical datums]]
[[Category:Geophysical observatories]]

{{Sourceattribution|Newlyn Tidal Observatory}}