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52.50343713.3930270Koordinaten: 52 ° 30 ' 12.4 "N, 13 ° 23' 34.9 " E

The mean sea level (also normal zero, abbreviated as NN or N. N. ) was from 1879 to 1992, the fixed zero level of official reference height in Germany. Colloquially, the obsolete designation above mean Germany is often used as a synonym for above sea level and incorrectly used for areas outside Germany or Europe.

Since 1993, the German main level network ( DHHN ) is to mean sea level ( MSL ) is inverted ( new height reference surface ). This step takes place in the wake of the merger of the networks height of the old and new federal states ( DHHN92 ) and in the context of Europe-wide standardization of height networks ( UELN ).

Definition

Normal zero denotes the height reference surface in the German main level network, which runs through the normal zero. The normal zero is a theoretical point, which is exactly 37 m under the decorated at the former New Berlin Observatory normal peak in 1879. For the name of elevation data of this system was originally " height above sea - zero" or set in an abbreviated " height above N. N. ". The level of the standard climax was transferred from Amsterdam level by precision leveling. The normal peak ( and thus indirectly the normal zero and ultimately sea level) was determined according to the inscription on March 22, 1878.

Sea level in the German main level network ( DHHN )

The normal peak in 1879 was replaced in 1912 (40 km east of the city center of Berlin ) because of termination of the observatory through the normal peak in 1912 near the hamlet Miincheberg Hoppe garden. The heights determined by Schleifennivellement without gravity measurements were also corrected with the normal gravity to normal - orthometric heights. The resulting height system is now called DHHN12. The values ​​were further identified with the suffix NN ( for sea level).

The height reference surface normal approaches zero the geoid at all bad - at high altitudes there may be differences of several decimeters. In addition, with the determination of heights besides the small random errors to model- based deviations, the so-called theoretical loop closing error. In the 1980s, has been in the Federal Republic of Germany therefore the conversion of the height system on a physical level model, the orthometric heights, decided ( DHHN85 ). Serving as the reference area should be further called geoid normal zero. This height system has been implemented only in a few countries, where it is also detached from the current DHHN92. Height information in the height reference DHHN92 be marked for easy identification with the addition NHN ( for mean sea level ).

Height systems in the GDR

In the GDR, sea level has been replaced since 1956 by a zero height ( HN) mentioned height reference surface. For this height system (now referred to as SNN56 ) were used as in many other countries of the Eastern bloc, normal heights. The date was of about 14 cm lower Kronstadt level. In East Berlin, at the height system of the Deutsche Reichsbahn and the inland waterways NN- ups were used unchanged in the GDR.