Editing Geoid (section)

==Temporal change==
{{See also|Geodesy#Temporal change}}
Recent satellite missions, such as the [[Gravity Field and Steady-State Ocean Circulation Explorer]] (GOCE) and 
[[GRACE (satellite)|GRACE]], have enabled the study of time-variable geoid signals. The first products based on GOCE satellite data became available online in June 2010, through the European Space Agency.<ref>{{cite web|url=http://www.esa.int/SPECIALS/GOCE/SEMB1EPK2AG_1.html|title=ESA makes first GOCE dataset available|date=9 June 2010|work=GOCE|publisher=[[European Space Agency]]|access-date=22 December 2016}}</ref><ref>{{cite web|url=http://www.esa.int/SPECIALS/GOCE/SEMY0FOZVAG_0.html|title=GOCE giving new insights into Earth's gravity|date=29 June 2010|work=GOCE|publisher=European Space Agency|access-date=22 December 2016|archive-date=2 July 2010|archive-url=https://web.archive.org/web/20100702013747/http://www.esa.int/SPECIALS/GOCE/SEMY0FOZVAG_0.html|url-status=dead}}</ref> ESA launched the satellite in March 2009 on a mission to map Earth's gravity with unprecedented accuracy and spatial resolution. On 31 March 2011, a new geoid model was unveiled at the Fourth International GOCE User Workshop hosted at the [[Technical University of Munich]], Germany.<ref>{{cite web|url=http://www.esa.int/esaCP/SEM1AK6UPLG_index_0.html|title=Earth's gravity revealed in unprecedented detail|date=31 March 2011|work=GOCE|publisher=European Space Agency|access-date=22 December 2016}}</ref> Studies using the time-variable geoid computed from GRACE data have provided information on global hydrologic cycles,<ref>{{cite journal|last1=Schmidt|first1=R.|last2=Schwintzer|first2=P.|last3=Flechtner|first3=F.|last4=Reigber|first4=C.|last5=Guntner|first5=A.|last6=Doll|first6=P.|last7=Ramillien|first7=G.|last8=Cazenave|first8=A.|author8-link=Anny Cazenave|last9=Petrovic|first9=S.| display-authors = 8|title=GRACE observations of changes in continental water storage|journal=Global and Planetary Change|volume=50|issue=1–2|pages=112–126|date=2006|doi=10.1016/j.gloplacha.2004.11.018|bibcode = 2006GPC....50..112S }}</ref> mass balances of [[ice sheet]]s,<ref>{{cite journal|last1=Ramillien|first1=G.|last2=Lombard|first2=A.|last3=Cazenave|first3=A.|author3-link=Anny Cazenave|last4=Ivins|first4=E.|last5=Llubes|first5=M.|last6=Remy|first6=F.|last7=Biancale|first7=R.|title=Interannual variations of the mass balance of the Antarctica and Greenland ice sheets from GRACE|journal=Global and Planetary Change|volume=53|pages=198|date=2006|doi=10.1016/j.gloplacha.2006.06.003|bibcode = 2006GPC....53..198R|issue=3 }}</ref> and [[postglacial rebound]].<ref>{{cite journal|last1=Vanderwal|first1=W.|last2=Wu|first2=P.|last3=Sideris|first3=M.|last4=Shum|first4=C.|title=Use of GRACE determined secular gravity rates for glacial isostatic adjustment studies in North-America|journal=Journal of Geodynamics|volume=46|pages=144|date=2008|doi=10.1016/j.jog.2008.03.007|bibcode = 2008JGeo...46..144V|issue=3–5 }}</ref> From postglacial rebound measurements, time-variable GRACE data can be used to deduce the [[viscosity]] of [[Earth's mantle]].<ref>{{cite journal|last1=Paulson|first1=Archie|last2=Zhong|first2=Shijie|last3=Wahr|first3=John|author-link3=John M. Wahr|title=Inference of mantle viscosity from GRACE and relative sea level data|journal=[[Geophysical Journal International]]|volume=171|pages=497|date=2007|doi=10.1111/j.1365-246X.2007.03556.x|bibcode = 2007GeoJI.171..497P|issue=2 |doi-access=free}}</ref>