# Geodetic System

The Estonian Geodetic System consists of:

1. Geodetic reference system - ETRS89
2. Plane coordinate system - L-EST97
3. Height system - EH2000
4. Gravity system - EG2000

## Geodetic reference system - ETRS89

In Estonia, the European Terrestrial Reference System 89 (ETRS89) is used as the geodetic reference system. ETRS89 coincides with the International Terrestrial Reference System (ITRS) of the International Earth Rotation Service (IERS) on epoch 1989.0 and is fixed in a stable part of the Eurasian lama. The parameters of the international reference ellipsoid GRS80 are used to calculate the geodetic coordinates. In Estonia, the coordinates of ETRS89 and the coordinates of the World Geodetic System 1984 (WGS84) are considered to be identical.

ETRS89 is realized in Estonia through the points of the first order geodetic network and their coordinates. In Estonia, three-dimensional Cartesian coordinates and geodetic coordinates of the realization of ETRS89 are denoted by the abbreviation EUREF-EST97.

## Plane coordinate system - L-EST97

The plane coordinate system is L-EST97. The coordinates of L-EST97 are calculated from the geodetic coordinates of EUREF-EST97 by using Lambert's two-dimensional conical conformational map projection LAMBERT-EST and the international reference ellipsoid GRS80.

The parameters for LAMBERT-EST are:
• Southern parallel BS = 58° 00' N
• Northern parallel BN = 59° 20' N
• Central meridian L0 = 24° 00' E
• Geodetic coordinates of the initial point:
B0 = 57° 31' 03".19415 N
L0 = 24° 00' E
• Plane coordinates of the initial point:
x = 6 375 000 m
y = 500 000 m

## Height system - EH2000

The height system is the European Vertical Reference System (EVRS). EVRS is a kinematic reference system which is defined by the Normaal Amsterdams Peil (NAP). A solid Earth-based zero-tide system is used and heights are expressed as geopotential numbers. To calculate normal heights from geopotential numbers, the normal gravity values of the reference ellipsoid GRS80 are used. The EVRS heights are abbreviated as EH2000. The calculation of EH2000 heights is based on the EVFR2007 solution.

The Estonian geoid model is EST-GEOID2017. The EST-GEOID2017 model is used for transformations between EUREF-EST97 ellipsoidal heights and EH2000 normal heights.

## Gravity system - EG2000

The gravity system EG2000 is realized through a set of gravity values of the first order gravity network points. Gravity values of the first order gravity network points at the epoch 2000 are based on the absolute gravity measurements performed according to the standards of IAGBN.

Last update: 27.11.2019 14:56
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