geoid

geoid

See also: Geoid

English

WOTD – 22 April 2017

Etymology

A map showing how the geoid (based on the EGM96 gravity model) compares with a theoretical perfect ellipsoid (the WGS84 reference ellipsoid) of the Earth. The red areas are higher and the blue areas lower than the idealized ellipsoid.

From German Geoid (“geoid”), analysable as geo- +‎ -oid.

Pronunciation

• (Received Pronunciation) IPA^(key): /ˈdʒiːɔɪd/

  • Audio (UK)

    (file)

• (General American) IPA^(key): /ˈd͡ʒiˌɔɪd/
• Hyphenation: ge‧oid

Noun

geoid (plural geoids)

1. (geography, geodesy) The shape, extending through landmasses (continents, etc.), that the surface of the oceans of the Earth would take under the influence of the Earth's gravity and rotation alone, disregarding other factors such as winds and tides; that is, a surface of constant gravitational potential at zero elevation.
   • 1888, Robert Simpson Woodward, “Introduction”, in On the Form and Position of the Sea Level: With Special Reference to Its Dependence on Superficial Masses Symmetrically Disposed about a Normal to the Earth's Surface (Bulletin of the United States Geological Survey; no. 48), Washington, D.C.: Government Printing Office, OCLC 459138679, page 15:

     The problem of the form and dimensions of the sea level surface of the earth has been one of peculiar difficulty. The combined efforts of the ablest mathematicians of the past two centuries, supplemented by the most laborious and costly geodetic measurements have yielded us the first approximation only to the complete solution. […] This spheroid, or reference ellipsoid, as it is sometimes called, has its minor axis coincident with the earth's axis of rotation and is usually regarded as sensibly fixed in position and dimensions. With respect to it the actual sea surface or geoid must be imagined to lie partly above and partly below by small but unknown amounts, the determination of which, if possible, will constitute a second approximation to the figure of the earth.

   • 1966, William P. Durbin, Jr., “Geophysical Correlations”, in Hyman Orlin, editor, Gravity Anomalies: Unsurveyed Areas: Papers Presented at the Symposium ‘Extension of Gravity Anomalies to Unsurveyed Areas,’ at Ohio State University, Columbus, November 18–20, 1964 (Geophysical Monograph Series; no. 9; American Geophysical Union Publication; no. 1357), Washington, D.C.: American Geophysical Union of the National Academy of Sciences—National Research Council, OCLC 976894946, page 87, column 2:

     In an earlier paper at Berkeley last year [Durbin, 1963], I suggested correlations between the local crust and the corresponding geoid undulation. Comparisons of crustal thickness with various geoids (gravimetric, astrogeodetic, and satellite) showed a general compatibility, not only in the United States but also in various other parts of the world.

   • 1995, Roger G. Hipkin, “How Close are We to a Centrimetric Geoid?”, in Hans Sünkel and Iginio Marson, editors, Gravity and Geoid: Joint Symposium of the International Gravity Commission and the International Geoid Commission: Symposium No. 113, Graz, Austria, September 11–17, 1994 (International Association of Geodesy Symposia; symposium 113), Berlin; Heidelberg: Springer-Verlag, DOI:10.1007/978-3-642-79721-7, →ISBN, page 529:

     This paper deals with the accuracy of a geoid computed using local gravity data supplemented by a global potential model. Local gravity can only correct the global model for wavelengths less than about one third of the dimension of local data, so any longer wavelength errors in the global geoid remain in the local model.

Related terms

• geoidal

Translations

surface of constant gravitational potential at zero elevation

Albanian: gjeoidi Arabic: مجسم أرضي‎ Armenian: գեոիդ (hy) (geoid) Asturian: xeoide m Belarusian: геоід m (hjeóid) Bulgarian: геоид m (geoid) Catalan: geoide m Chinese: Mandarin: 大地水准面 Czech: geoid m Danish: geoide Dutch: geoïde f Esperanto: geoido Estonian: geoid (et) Finnish: geoidi (fi), geoidipinta French: géoïde (fr) m Galician: xeoide m Georgian: გეოიდი (geoidi) German: Geoid m Greek: γεωειδές (el) n (geoeidés) Hebrew: גאואיד‎ Hungarian: geoid Icelandic: jarðsporvala f Ido: geoido (io) Indonesian: geoid Italian: geoide (it) m Japanese: ジオイド Kazakh: геоид (geoid) Korean: 지오이드 (jioideu) Luxembourgish: Geoid m Norwegian: geoide (no) Nynorsk: geoide Persian: زمین‌واره‎ Polish: geoida f Portuguese: geoide Romanian: geoid (ro) Russian: гео́ид (ru) m (geóid) Serbo-Croatian: geoid (sh) m Slovak: geoid m Slovene: geoid m Spanish: geoide m Swedish: geoid Thai: จีออยด์ Turkish: geoit (tr) Ukrainian: геоїд m (heojid) Uzbek: geoid Vietnamese: geoid (vi) Zazaki: geoid

See also

• ellipsoid

Further reading

• geoid on Wikipedia.Wikipedia

Anagrams

• Diego, diego, dogie

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Czech

Pronunciation

• IPA^(key): [ˈɡɛoɪt]
• Rhymes: -ojt
• Hyphenation: ge‧oid

Noun

geoid m inan

1. (geography, geodesy) geoid

Declension

Declension of geoid

	singulare tantum
nominative	geoid
genitive	geoidu
dative	geoidu
accusative	geoid
vocative	geoide
locative	geoidu
instrumental	geoidem

Further reading

• geoid in Příruční slovník jazyka českého, 1935–1957
• geoid in Slovník spisovného jazyka českého, 1960–1971, 1989

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Romanian

Etymology

From French géoïde.

Noun

geoid n (uncountable)

1. geoid

Declension

declension of geoid (singular only)

	singular
n gender	indefinite articulation	definite articulation
nominative/accusative	(un) geoid	geoidul
genitive/dative	(unui) geoid	geoidului
vocative	geoidule