Chart datum above ellipsoid

Current version: 2025a. New versions will be published as the underlying dataset is

improved. The model gives the vertical separation between chart datum and the ellipsoid

(EUREF89) on a regular geographic grid (0.005° × 0.01°), covering the coastal region of

mainland Norway.

Chart datum (CD) is defined via Lowest Astronomical Tide (LAT). North of Utsira/Karmsundet

CD is identical to LAT. From Utsira to the Swedish border CD is 20cm below LAT, and in the

inner parts of the Oslo fjord, CD is 30cm below LAT.

The model is a combination of the models for Mean sea level above the ellipsoid and Mean

sea level above chart datum, so the quality depends on those two models.

An estimate of the standard deviation of the model is included as a separate band in the GeoTIFF file. When selecting the bin-format, one gets a separate file with the gridded standard deviation.

Date (Creation): 2021-01-22

Date (Publication): 2021-01-22

Date (Revision): 2025-02-03

Code: sjokartnull_over_ellipsoiden

Point of contact

Organisation name	Individual name	Electronic mail address	Role
Norwegian Mapping Authority		tidevann@kartverket.no	Publisher
Norwegian Mapping Authority		tidevann@kartverket.no	Owner

Maintenance and update frequency: Unknown

Keywords

separasjonsmodell

Specific usage: The model can be used for converting heights measured by GNSS to chart datum.

User contact info

Organisation name	Individual name	Electronic mail address	Role
			Owner

Access constraints: Other restrictions

Other constraints: Åpne data

Use constraints: Other restrictions

Other constraints: Creative Commons BY 4.0 (CC BY 4.0)

Spatial representation type: Grid

Language: Norwegian

Topic category

Oceans

Supplemental Information: Bin-formatet er det same binære formatet som vert brukt for høgdereferansemodellane for NN2000 of NN1954, so programvare som kan lese dei filene bør også kunne lese desse.