Regional Adjustment of Precise Levellings around the Baltic

摘要

We have performed a regional joint adjustment, in this paper called BLR2000 (Baltic Levelling Ring) of all levellings around the Baltic. Its characteristics are: (1) The datum is the Normaal Amsterdams Peil (NAP), the same as for the European Vertical Reference Frame 2000 (EVRF2000). (2) All levellings are corrected for vertical motion to the epoch 2000.0. (3) The zero-tidal system is used. (4) Geopotential numbers are transformed into normal heights. The work supports the incorporation of the new data into the United European Levelling Network (UELN) and into EVRF. It is also an important element in the creation of new national height systems: the new Swedish height system RH 2000 adopted in 2005 is a subset of BLR2000. The results give information about the dynamic mean topography of the Baltic, and resolve the question about the large apparent closing error in the EVRF2000 across the Gulf of Finland.