European Combined Geodetic Network (ECGN) is a research project aimed at high accuracy geoid

Geoid

The geoid is that equipotential surface which would coincide exactly with the mean ocean surface of the Earth, if the oceans were in equilibrium, at rest , and extended through the continents . According to C.F...

 determination. The purpose of ECGN is to connect the height systems obtained via geometric positioning by GNSS with gravity-referenced heights with a cm-level accuracy. The effects of the atmosphere

Atmosphere

An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

, the ocean

Ocean

An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...

s and time-dependent parameters of the solid Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

 on the gravity field are investigated. ECGN uses the data of satellite gravity missions CHAMP

CHAMP

CHAllenging Minisatellite Payload is a German satellite launched July 15, 2000 from Plesetsk, Russia and was used for atmospheric and ionospheric research, as well as other geoscientific applications, such as GPS radio occultation....

, GRACE

Gravity Recovery and Climate Experiment

The Gravity Recovery And Climate Experiment , a joint mission of NASA and the German Space Agency, has been making detailed measurements of Earth's gravity field since its launch in March 2002....

 and GOCE

Goce

Goce is an opera composed by Kiril Makedonski in tribute to Gotse Delchev. The work was commissioned to be the very first opera performed by the Macedonian National Opera Company. It premiered on May 24, 1954 and it is the first opera to be written in the Macedonian language....

 to model the Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

's gravity field and is linked to other gravity-related projects (GMES

GMES

Global Monitoring for Environment and Security is a joint initiative of the European Commission and European Space Agency, which aims at achieving an autonomous and operational Earth observation capacity....

, GEOSS, GGOS). The ECGN is considered as a Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

an contribution to the IAG

IAG

IAG may mean:* IAG – The IATA code for Niagara Falls International Airport* IAg – Immersion Silver plating, a conductor plating technology used for Printed circuit boards...

 project Global Geodetic Observation System (GGOS). ECGN is managed by EUREF

Regional Reference Frame Sub-Commission for Europe

Regional Reference Frame Sub-Commission for Europe is the sub-commission of the International Association of Geodesy , part of the Sub-Commission 1.3 , under IAG Commission 1 ....

.