Editing Tide gauge

{{short description|Device for measuring the change in sea level relative to a datum}}
[[File:Tidal gauge dsc06189.jpg|thumb|right|A tide gauge]]
[[File:Kronstadt tide gauge.JPG|thumb|right|The tide gauge in [[Kronstadt]], Russia<ref>{{cite web |title=The Kronstadt sea-gauge |website=Your Guide in St Petersburg |url=http://www.visit-saint-petersburg.ru/sea-gauge/ |access-date=26 April 2019}} With explanatory diagram showing Lea-type float gauge and stilling-well.</ref>]]

A '''tide gauge''' is a device for measuring the change in [[sea level]] relative to a [[vertical datum]].<ref>{{Cite journal |last1=Iliffe |first1=J. C. |last2=Ziebart |first2=M. K. |last3=Turner |first3=J. F. |date=2007 |title=A New Methodology for Incorporating Tide Gauge Data in Sea Surface Topography Models |url=https://www.tandfonline.com/doi/full/10.1080/01490410701568384 |journal=Marine Geodesy |language=en |volume=30 |issue=4 |pages=271–296 |doi=10.1080/01490410701568384 |bibcode=2007MarGe..30..271I |issn=0149-0419 |access-date=27 July 2024|url-access=subscription }}</ref><ref>{{Cite journal |last=Mitchum |first=Gary T. |date=2000 |title=An Improved Calibration of Satellite Altimetric Heights Using Tide Gauge Sea Levels with Adjustment for Land Motion |url=http://www.tandfonline.com/doi/abs/10.1080/01490410050128591 |journal=Marine Geodesy |language=en |volume=23 |issue=3 |pages=145–166 |doi=10.1080/01490410050128591 |bibcode=2000MarGe..23..145M |issn=0149-0419 |access-date=27 July 2024|url-access=subscription }}</ref> It is also known as a '''mareograph''',<ref name="Torge2012">{{cite book | last1=Torge | first1=W. | last2=Müller | first2=J. | title=Geodesy | publisher=De Gruyter | series=De Gruyter Textbook | year=2012 | isbn=978-3-11-025000-8 | url=https://books.google.com/books?id=RcfmBQAAQBAJ | access-date=2021-12-08 | page=80}}</ref> '''marigraph''',<ref>{{cite web |url=http://itic.ioc-unesco.org/index.php?option=com_content&view=article&id=1023:9&catid=1142&Itemid=2433 |title=4. Tide, Mareograph, Sea Level |author=International Tsunami Information Center |publisher=[[UNESCO]] |access-date=2014-06-16 |archive-date=2018-07-24 |archive-url=https://web.archive.org/web/20180724032123/http://itic.ioc-unesco.org/index.php?option=com_content&view=article&id=1023:9&catid=1142&Itemid=2433 |url-status=dead }}</ref> and '''sea-level recorder'''.<ref>{{cite book |title=Handbook of Sea-Level Research |editor1=Ian Shennan |editor2=Antony J. Long |editor3=Benjamin P. Horton |url=https://books.google.com/books?id=ErbEBgAAQBAJ&pg=PA557|year=2015|publisher=Wiley|isbn=978-1-118-45257-8|page=557}}</ref>
When applied to [[freshwater]] continental [[water body|water bodies]], the instrument may also be called a '''limnimeter'''.<ref name="Merriam-Webster 2022">{{cite web | title=Definition of LIMNIMETER | website=Merriam-Webster | date=2022-10-07 | url=https://www.merriam-webster.com/dictionary/limnimeter | access-date=2022-10-07}}</ref><ref>{{Cite web|title=Definition of LIMNIMETER|url=https://www.merriam-webster.com/dictionary/limnimeter|access-date=2021-08-14|website=www.merriam-webster.com|language=en}}</ref>

==Operation==
Sensors continuously record the height of the [[water level]] with respect to a height reference surface close to the [[geoid]]. Water enters the device by the bottom pipe (far end of the tube, see picture), and electronic sensors measure its height and send the data to a tiny computer.{{citation needed|date=May 2018}}

Historical data are available for about 1,450 stations worldwide, of which about 950 have provided updates to the global data center since January 2010.<ref>{{cite web|title=Obtaining Tide Gauge Data|url=http://www.psmsl.org/data/obtaining/|website=Permanent Service for Mean Sea Level|publisher=PSMSL|access-date=2016-03-07|ref=PSMSL_data}}</ref> At some places records cover centuries, for example in [[Amsterdam]] where data dating back to 1700 is available.<ref>{{cite web|url=http://www.psmsl.org/data/longrecords/|title=Other Long Records not in the PSMSL Data Set|access-date=2015-05-11|publisher=PSMSL}}</ref>

When it comes to estimating the greater ocean picture, new modern tide gauges can often be improved upon by using satellite data.{{citation needed|date=May 2018}}

Tide gauges are used to measure [[tides]] and quantify the size of [[tsunami]]s. The measurements make it possible to derive the mean [[sea level]]. Using this method, sea level slopes up to several 0.1 m/1000&nbsp;km and more have been detected.{{citation needed|date=May 2018}}

A tsunami can be detected when the sea level begins to rise, although warnings from [[seismic activity]] can be more useful.{{citation needed|date=May 2018}}

==History==
Sea-level measurements were made using simple measuring poles or "tide staffs" until around 1830, when self-recording gauges with mechanical [[Float (nautical)|floats]] and stilling wells were introduced.<ref>[http://noc.ac.uk/science-technology/climate-sea-level/sea-level/tides/tide-gauges/tide-gauge-instrumentation Tide gauge history UK National Oceanographic Centre] {{Webarchive|url=https://web.archive.org/web/20150824020453/http://noc.ac.uk/science-technology/climate-sea-level/sea-level/tides/tide-gauges/tide-gauge-instrumentation |date=2015-08-24 }}</ref>

Tidal poles and float gauges were the primary means of sea-level measurement for over 150 years and continue to operate at some locations today. While still part of modern-day tide gauge instrumentation, these technologies have since been superseded by pressure gauges (similar to [[depth gauge]]s), acoustic/ultrasonic gauges, and radar gauges.{{citation needed|date=May 2018}}

The following types of tide gauges have been used historically:<ref>{{cite web|title=History of tide gauges|url=http://tide.gsi.go.jp/ENGLISH/history.html|work=Tide Observation|publisher=[[Geospatial Information Authority of Japan]]|access-date=2014-04-19|archive-date=2013-01-05|archive-url=https://web.archive.org/web/20130105092332/http://tide.gsi.go.jp/ENGLISH/history.html|url-status=dead}}</ref>

* Kelvin type tide gauge
* Fuess type tide gauge
* GSI type tide gauge
* High accuracy automatic tide gauge
* High resolution automatic tide gauge

==Common applications==
[[File:CascaisTideGauge Interior.jpg|thumb|200px|Interior view of Cascais Tide Gauge showing data recording equipment]]
Tide gauges have a practical application in the shipping and fishing industries where low or high tide levels can hinder or prohibit access to shallow bays or locations with bridges. An example is the [[Cascais tide gauge]] in Portugal, which was originally installed because of the sand bar in the River [[Tagus]] that causes difficulties for shipping entering [[Lisbon]] port. Because of similar problems many industries have installed private tide gauges in ports around the world, and also rely on government agencies (such as [[NOAA]]).

Data collected from tide gauges is also of interest to scientists measuring global weather patterns, the mean sea water level, and trends - notably those potentially associated with global warming.

==Modern gauges==
In recent years new technologies have developed allowing for real-time, remote tide information to be published online via a solar powered wireless connection to a tide sensor.  Acoustic/ultrasonic sensors<ref>{{cite web|url=http://www.maxbotix.com/articles/055.htm|title=Remote Monitoring a MaxSonar®|access-date=2012-09-28|archive-date=2012-09-03|archive-url=https://web.archive.org/web/20120903032512/http://www.maxbotix.com/articles/055.htm|url-status=dead}}</ref> have already been deployed to great effect and the data is regularly broadcast via [[Twitter]] and also displayed online.<ref>{{cite web|url=http://www.iobridge.com/apps/tide/ockway_bay|title=ioBridge Apps - Ockway Bay Tide Levels|access-date=2012-09-28|archive-date=2012-01-21|archive-url=https://web.archive.org/web/20120121215442/http://www.iobridge.com/apps/tide/ockway_bay|url-status=dead}}</ref>

==See also==
{{portal|Oceans}}
*[[Level sensor]]
*[[Sea level rise]]
*[[Stream gauge]]
*[[Fort Denison#Tide gauge]]

==References==
{{reflist}}

==Further reading==
*{{cite book|author=Gerd Morgenschweis|title=Hydrometrie: Theorie und Praxis der Durchflussmessung in offenen Gerinnen|url=https://books.google.com/books?id=Rp8gywGrwyAC&pg=PA70|year=2010|publisher=Springer-Verlag|isbn=978-3-642-05390-0}} {{in lang|de}}

==External links==
{{commons category|Tide gauges}}
*[http://tide.gsi.go.jp/ENGLISH/history.html Historical Examples] {{Webarchive|url=https://web.archive.org/web/20130105092332/http://tide.gsi.go.jp/ENGLISH/history.html |date=2013-01-05 }} Brown University
*[http://sealevel.colorado.edu/tide-gauge-sea-level Mean Sea Level Explanation]
*[http://tidesandcurrents.noaa.gov/ NOAA Tide Data]

{{Meteorological equipment}}
{{physical oceanography}}
{{Authority control}}

{{DEFAULTSORT:Tide Gauge}}
[[Category:Tide gauges|*]]