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Topic: Tide gauge

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	TIDE - LoveToKnow Article on TIDE (Site not responding. Last check: 2007-10-15)
		Tide- Tables and the Degree of Accuracy in Tidal Predictian.i The connection between the tides and the movements of the ~n,pandricai moon and sun is so obvious that tidal predictions Ti*-tabiea.
		All the s ate equal to unity at the pole hence the hypothesis that C does not tend to zero leads to the conclusion tha~ the tide is of infinite height at the pole The expansion of the height of tide is essentially convergent, and therefore the hypothesis is negatived.
		These two tides proceed according to sidereal time and arise from the sun and moon jointly, and a synthesis of the two parts of each is effected in the harmonic method, although that synthesis is not explained in chapter iv.
	www.1911encyclopedia.org /T/TI/TIDE.htm (21009 words)

	Hunting - Glossary - Discover The Outdoors (Site not responding. Last check: 2007-10-15)
		The observed tide and tidal current can be considered the result of the combination of several tidal waves, each of which may vary from nearly pure progressive to nearly pure standing and with differing periods, heights, phase relationships, and direction.
		Tide reducers are used to correct the soundings throughout the hydrographic survey area to a common, uniform, uninterrupted chart datum.
		In the mixed type of tide the diurnal and semidiurnal waves are both important factors and the tide is characterized by large inequality in the high or low water heights or in both.
	www.dto.com /hunting/glossary/index.jsp?startwith=t (3638 words)

	Continuous GPS positioning of MARSEILLE tide gauge
		The main objective of this GPS station is to determine the vertical land motion that 'contaminates' the tide gauge record.
		Tide gauge data analysis show that the observed sea-level trend at Marseille can be estimated with a 'statistical' error lower than about 0.1 mm/yr.
		Moreover, by examining the relative long height history of the Marseille tide gauge benchmarks, one can confirm and conclude that the tide gauge building has not undergone any significant local relative subsidence and that it can be viewed as stable at the sub-millimeter level with respect to the bedrock.
	www.soest.hawaii.edu /cgps_tg/casestudy/case3_files (1206 words)

	Manly Hydraulics Laboratory (Site not responding. Last check: 2007-10-15)
		Tides or tidal currents occurring near the times of maximum north or south declination of the Moon are called tropic tides or tropic currents, and those occurring when the Moon is over the Equator are called equatorial tides or equatorial currents.
		Thus, the tide is said to be diurnal when only one high water and one low water occur during a tidal day, and the tidal current is said to be diurnal when there is a single flood and a single ebb period of a reversing current in the tidal day.
		In a normal semidiurnal tide, duration of rise and duration of fall each will be approximately equal to 6.21 hours, but in shallow waters and in rivers there is a tendency for a decrease in duration of rise and a corresponding increase in duration of fall.
	www.mhl.nsw.gov.au /www/tide_glossary.htmlx (5222 words)

	Water Level Measurement -
		It’s also necessary to recognize that a tide gauge, an instrument that automatically records water levels at fixed intervals of time, is only one part of a tide station.
		Tide Staff – A tide staff graduated in feet or centimeters is installed in a permanent housing mounted next to the tide gauge.
		Tide Gauge – Mechanical devices for recording water level are still in use but these are mostly being replaced by acoustic water level meters that measure and record data electronically.
	www.vims.edu /physical/research/TCTutorial/tidemeasure.htm (640 words)

	Tide Gauge Comparisons
		The scattered gauge results compare fairly well with the altimetry with the exception of the anomalous Easter Island gauge which was probably relocated during the 8 year gap.
		The gauge observations for the two time periods were taken by averaging the month-month gauge means over a 5 yr gap (for Geosat-Ers1) and 8 yr (for Geosat-T/P) in the same sense and over the same months as in the Pathfinder altimetric DSCs (21 months for Geosat-Ers1, 87 April 92 thru.
		The fact that the power of the altimeter residual predictions at the gauges are always less than the power of the gauge data is probably due more to the averaging of the altimetry over the 2x3 degree bins than the aliasing of power away from the ocean effects into the geopotential solution.
	ibis.grdl.noaa.gov /SAT/pubs/papers/wagner_2000/node13.html (1340 words)

	Global mean sea level tide gauges
		Tide gauges, usually placed on piers, measure the sea level relative to a nearby geodetic benchmark.
		Tide gauges may also move vertically with the region as a result of post-glacial rebound, tectonic uplift or crustal subsidence.
		Major conclusions from tide gauge data have been that global sea level has risen approximately 10-25 cm during the past century.
	sealevel.colorado.edu /tidegauges.html (276 words)

	AVISO Altimetry - Newsletter 5 - Altimeter drift from tide gauges (Site not responding. Last check: 2007-10-15)
		Comparisons with tide gauge sea levels are particularly useful because these data in principle measure exactly the same physical variable as the altimeter measures, and also because the in situ data allow an evaluation of the total altimetric system, including environmental corrections as well as instrumental errors, for example.
		Although the tide staff readings are noisy, and are taken only several times per week, over time these data can be used to monitor the stability of the nearly continuously sampled tide gauge sea levels.
		That is, there was an unknown drift in the data, which the tide gauges provided a time series for, and then the exact drift was determined independently, giving a way to evaluate the success of the tide gauge method in determining the drift.
	www-aviso.cnes.fr:8090 /HTML/information/publication/news/news5/mitchum_uk.html (2024 words)

	GPS/Tide Gauge Information
		Tide Gauges and GPS Sites in the Northeastern U.S. For investigations of long term sea level variability, only tide gauges with records longer than 30-50 years are useful, since it takes the averaging of much more tide gauge data to determine long-term sea level change than it does GPS observations to determine long-term crustal motion.
		A number of tide gauges on the east coast have been operational for 50 years or longer, thus these gauges should initially be targeted for GPS monitoring.
		Tide gauge corrections based on numerical models of post-glacial rebound are sensitive to the visco-elastic structure adopted for Earth models.
	www.csr.utexas.edu /projects/gps/info.html (566 words)

	Sea level
		To an operator of a tide gauge, MSL means the 'still water level' - the level of the sea with motions such as wind waves averaged out - averaged over a period of time such that changes in sea level - e.g.
		Hence a change in MSL can result from a real change in sea level, or from a change in the height of the land on which the tide gauge operates.
		To extend this definition far from land means comparing the local height of the mean sea surface with a 'level' reference surface, or datum, called the geoid.
	www.brainyencyclopedia.com /encyclopedia/s/se/sea_level.html (466 words)

	GLOSS Bulletin Editorial Issue 6 (Site not responding. Last check: 2007-10-15)
		Tide gauge measurements reflect vertical motions of both the land (to which the gauge is attached) and the sea surface.
		Tide gauges that can be instrumented with CGPS for the purposes of the centimeter agenda may often be unsuitable for pursuing the millimeter agenda.
		If a tide gauge and a non-colocated CGPS station are not constructed on a coherent outcrop of solid rock, the possibility of subsurface displacements changing the relative level of the tide gauge and the GPS antenna is present even when near-surface 'engineering' instability of a pier or a harbor wall can be ruled out.
	www.nbi.ac.uk /psmsl/gb/gb6/bevis.html (2279 words)

	NASA Earth Science Data and Services: 1995 Edition: Rising above Tide Gauges (Site not responding. Last check: 2007-10-15)
		According to long-term averages estimated from tide gauge measurements, global mean sea level has been rising at a rate of only one to two millimeters per year over the last century.
		Tide gauge data have been venerable but imperfect indicators of variations in global mean sea level.
		The gauges are few and far between, and are always at the edge of the land.
	nasadaacs.eos.nasa.gov /articles/95/tide.html (677 words)

	Sea Surface Height Validation: Tide Gauge Comparison (Site not responding. Last check: 2007-10-15)
		For a given tide gauge, the daily values were compared to the altimeter heights at a chosen location of the colinear ground track.
		The altimeter location was chosen by minimizing the distance from the tide gauge while maximizing the number of cycles of valid data.
		The tide gauge data were interpolated at the time of the altimeter observation, which in turn has been corrected for all instrument and media biases, as well as surface models (tide effects removed).
	iliad.gsfc.nasa.gov /opf/tgauge.html (146 words)

	[No title]
		Summerson, R.M.V., Handsworth, R.J. and Lennon, G.W. (1993): New Antarctic tide gauges.
		Automatic tide gauge Esperanza, Tides were recorded with a float automatic recorder (scale 1:12) Filing of Data: Servicio de Hidrografia Naval Republica Argentina Report to SCAR on Antarctic Scientific Activities for the Year 1965 and planned program for 1967 Instituto Antartico Argentino, Buenos Aires, 1966 p12 IX.
		This pressure-type tide gauge is connected by an underwater cable to a PC in the Station so that recent logged in the gauge can be retrieved at any time.
	www.geoscience.scar.org /geodesy/perm_ob/tide/atg_summary.txt (5276 words)

	In situ tide gauge/GPS stations for monitoring the temporal drift of satellite altimeters
		The goal of this project is to estimate vertical land movements at each tide gauge to a 1 mm/yr accuracy for calibration of the Jason-1 and subsequent altimeter missions.
		Water level switch and tide staff observations are also made to monitor the stability of the tide gauge measurement.
		Core stations for tide gauge positioning - many of the stations used to establish ITRF were chosen without consideration for vertical stability or low satellite elevation angles.
	sealevel.jpl.nasa.gov /science/invest-merrifield.html (589 words)

	UHSLC CGPS Background
		The feasibility of using tide gauges to monitor altimeter drift was demonstrated recently by Mitchum (1998a) using a set of over 50 stations from around the world.
		Tide gauges measure sea level relative to the land or structure on which the gauge rests (Figure 1).
		The Honolulu tide gauge is one of the longest continuous records in the Pacific Ocean dating back to 1905 (Figure 4).
	ilikai.soest.hawaii.edu /uhslc/gpsd/CGPS.wp (783 words)

	NOAA/CEOB Tide Glossary (Site not responding. Last check: 2007-10-15)
		Tides of decreased range or currents of decreased speed occurring monthly as the result of the Moon being in apogee.
		The apogean range (An) of the tide is the average range occurring at the time of apogean tides and is most conveniently computed from the harmonic constants.
		It is smaller than the mean range, where the type of tide is either semidiurnal or mixed, and is of no practical significance where the type of tide is predominantly diurnal.
	www.baysail.com /tide_terms (1452 words)

	Table 12
		Data variable - longitude of the tide- gauge station used in determining the sea-level trends.
		Data variable - latitude of the tide- gauge station used in determining the sea-level trends.
		Data variable - maximum tide range, maximum measured range for the gauge station in 1992 (this value may be the "spring" or "diurnal" tide range, depending on geographic location); values in meters.
	cdiac.esd.ornl.gov /epubs/ndp/ndp043c/tables/table12.htm (290 words)

	Geodetic aspects of long term sea level variations in European seas from altimetry and tide gauge data
		The agreement with the absolute sea level variations obtained from tide gauge data, as well as the correlation with air temperature and air pressure at the tide gauge stations are investigated.
		The observations of the SSHs at the tide gauge stations are relative to the earth crust and, as a consequence, do not allow to distinguish between a sea level increase and an earth subsidence phenomena [Woodworth et al, 1990], [Emery and Aubrey, 1991].
		The tide gauges monthly mean SSH anomalies have been computed subtracting the mean over all the available months in the years from January 1992 to December 1995 from the monthly means provided by the PSMSL and by WOCE.
	earth.esa.int /symposia/ers97/papers/fenoglio1 (2487 words)

	[No title]
		Tide gauge benchmark (TGBM) description: USGS 1: The standard disk, stamped 'No.1 1969', is set in concrete deck at three feet north of Net P Pier Warehouse (established 1969).
		UH B-2: The standard silver disk is set in concrete 21 feet from the south eastern corner of the gauge house (established Apr 1981).
		UH B-3: The standard silver disk is set in concrete 50 feet from the south eastern corner of the gauge house (established Apr 1981).
	www.nodc.noaa.gov /woce_V2/disk09/del_mode/ascii/g115.txt (414 words)

	Global mean sea level calibration
		For the tide gauge calibrations, global mean sea level during the period of TOPEX-A operation is used as zero level for TOPEX-B, POSEIDON, and Jason.
		A number of gauges, however, have a significant lag in reporting of records and are not available for the Jason calibration.
		We have restricted the ~100 available gauges to a set of 64 near real-time stations that span the majority of both the T/P and Jason missions, and will therefore provide a relatively consistent calibration for both.
	sealevel.colorado.edu /calibration.html (326 words)

	NOAA Magazine Online (Story 139)
		The tide gauge, now operated by the NOAA Center for Operational Oceanographic Products and Services (part of the NOAA Ocean Service), is one of 175 stations in the NOAA National Water Level Observation Network, which spans the entire continental United States, Alaska, Hawaii, Pacific Island territories, Puerto Rico and the Virgin Islands.
		Tidal datums derived from NOAA tide gauges have traditionally been used for navigation (e.g., establishing chart datum and shoreline datums for all nautical chart products and for the Physical Oceanographic Real-Time System operations), however there are many other beneficial applications for this data.
		The tide gauge also provides information critical to maintaining and improving economic prosperity for California (and the nation), contributes to maintaining and monitoring port activities essential to Homeland Security and provides water level and reference datum information needed for the increasing number habitat and marsh restoration programs in the bay region.
	www.magazine.noaa.gov /stories/mag139.htm (1476 words)

	Encyclopedia: Sea level (Site not responding. Last check: 2007-10-15)
		In a state of rest or absence of external forces, the mean sea level would coincide with this geoid surface, being an equipotential surface of the Earth's gravity field.
		Local âmean sea levelâ (LMSL) is defined as the height of the sea with respect to a land benchmark, averaged over a period of time, such as a month or a year, long enough that fluctuations caused by waves and tides are largely removed.
		A common perception is that the rate of sea level rise should have accelerated during the latter half of the 20th century.
	www.nationmaster.com /encyclopedia/Sea-level (241 words)

	IUGG 2003 Scientific Program (Site not responding. Last check: 2007-10-15)
		Measurement of sea level change has been traditionally based on tide gauge records which indicate an average rate of sea level rise in the range 1-2 mm/yr for the 20th century.
		Tide gauges however are located at continents or islands coastlines, hence they do not allow to sample the spatial variations of the sea level change at the global scale.
		We confirm that sub sampling the steric (temperature and salinity) sea level at the usual tide gauge locations where long time series records are available leads to a steric sea level rise twice as large as the ′true′ global mean.
	www.olympus.net /IAPSO/abstracts03/JSP05/01/019708-1.html (301 words)

	g31d in fm01
		Tide gauges however are located at continents or islands coastlines, hence do not globally sample the spatial variations of the sea level change.
		Tide gauge records of sea-level rates exhibit significant geographic variations, even after correction for the ongoing signal due to glacial isostatic adjustment.
		The tide gauges are approximately colocated with the GPS array and the majority are sampling the Baltic Sea and its sub-basins; hence a regionally constant sea level term is expected to correlate primarily with a change of the North Atlantic level at the North Sea-Skagerak-Kattegat.
	www.agu.org /cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&range=1&directget=1&application=fm01&database=/data/epubs/wais/indexes/fm01/fm01&maxhits=200&="G31D" (3287 words)

	Tide Gauge
		As a result, the Atlantic City tide gage is being used as the reference for the county.
		The time difference between the high and low tides along the county's oceanfront and those at the Atlantic City gage is generally less than 15 minutes.
		Being that the reference gage is on the oceanfront, the tide level associated with that particular location may vary somewhat from event to event based on the number of tide cycles during which there is an onshore flow.
	home.comcast.net /~wx2nj/tides.html (544 words)

	AMS Glossary
		The tide gauge datum is a horizontal plane defined at a fixed arbitrary level below a tide gauge benchmark.
		The heights in tide tables are usually measured from chart datum rather than mean sea level.
		Sometimes, the consequent horizontal movement of water along the coastlines is also called “tide,” but it is preferable to designate the latter as tidal current, reserving the name tide for the vertical wavelike movement.
	amsglossary.allenpress.com /glossary/browse?s=t&p=30 (522 words)

	Variations in Sea Level
		Tide staff at Solomons Island, MD Tide gauges around the Chesapeake Bay indicate that the relative sea level in the Bay is rising at twice the average global rate of 1.8 mm per year [Douglas, 1991].
		Tide gauges on the Chesapeake Bay are again emphasized using a different color.
		Tide gauges measure sea level changes relative to the land on which the the tide gauge rests.
	www.ngs.noaa.gov /GRD/GPS/Projects/CB/SEALEVEL/sealevel.html (1465 words)

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