GEOID

http://en.wikipedia.org/wiki/Geoid

http://www.universetoday.com/116801/the-potsdam-gravity-potato-shows-earths-gravity-variations/

http://www.ngs.noaa.gov/GEOID/

https://directory.eoportal.org/web/eoportal/satellite-missions/g/goce

http://www.esri.com/news/arcuser/0703/geoid1of3.html

http://earthobservatory.nasa.gov/Features/GRACE/page3.php

via European Space Agency

http://www.esa.int/spaceinimages/Images/2013/11/GOCE_reenters_atmosphere

http://www.esa.int/Our_Activities/Observing_the_Earth/GOCE

http://esamultimedia.esa.int/multimedia/publications/BR-314/

Gravity 'dip'

http://www.esa.int/Our_Activities/Observing_the_Earth/GOCE/GOCE_reveals_gravity_dip_from_ice_loss

http://news.discovery.com/earth/global-warming/earths-gravity-dips-from-antarctic-ice-loss-141001.htm