Use constraints: These data sets are a piece of scientific work which relies on free interchange of scientific data. Therefore the data are available for scientific research only. The data must not be used for navigation. Any commercial use is prohibited. Any kind of warranty is excluded.

These depth contours have been created for MARIS, the Maritime Accident Response Information System for Baltic Sea, from the "High resolution spherical grid topography of the Baltic Sea" provided by the Baltic Sea Research Institute Warnemünde (IOW, http://www.io-warnemuende.de/research/en_iowtopo.html) with ArcView 3.2 and Spatial Analyst Extension. To get depth contours that better match the coastline data used in this project, the grid acquired from the IOW was complemented with points derived from this coastline dataset and given the depth value of zero.

Contours were created using Inverse Distance Weight -algorithm and 10

points average. The contour interval was 10 meters and from these only the depths of 10, 20, 50, 100, 200, 300, 400 and 500 meters were chosen to the final dataset.

In June 2005, the dataset was converted from WGS 1984 (World Mercator) to ETRS 1989 LAEA for use in HELCOM's web-based Baltic GIS.

Below are the remarks regarding the original point dataset from IOW:

The dataset provides a digitised topography of the Baltic Sea. Land heights and water depths have been calculated for a regular spherical grid from available data. Dataset covers the whole Baltic Sea from 9° to 31° East and from 53°30’ to 66° North by (660 x 750) grid cells. The resolution is 2 minutes with respect to longitude, and 1 minute to latitude. This is approximately 1 nautical mile, or 2 km resp. The dataset was published at the Baltic Sea Science Congress in Stockholm on 27. November 2001 as poster 147. A short description of the data compilation has been published on-line.

The data specify a representative average of the water depth or the land height of each grid cell, counted by negative and positive values in meters. Some statistical parameters allow a rough estimate of the reliability of the data. (Please be aware that data are rather uncertain in regions where strong gradients of the bottom relief occur, esp. the northern parts of the Baltic. There is an urgent need of further bathymetry data to become available for the Baltic beyond 59° North.) Since a common average of land heights and water depths lead to rather unsatisfying results with respect to the gridded shoreline, a landmask is proposed in both data sets. The landmasks were derived from the global high resolution shorelines GSHHS (www.soest.hawaii.edu/wessel/gshhs/gshhs.html) and RANGS (www.io-warnemuende.de/homepages/rfeistel/index.html), and used to get a "naturally looking" composite topography.

Reference

The application of the data has to be cited as scientific work by: T.

Seifert, F. Tauber, B. Kayser: 2001: "A high resolution spherical grid

topography of the Baltic Sea – revised edition", Proceedings of the Baltic

Sea Science Congress, Stockholm 25-29. November 2001 (to be published). Any contribution to a further improvement of the data is welcome, please

contact torsten.seifert@io-warnemuende.de