This dataset consists of a 1x1km grid where cell values reflect the number of voyages that have travelled through the respective grid cell. To calculate this value, tracks of ship movements are reconstructed that results in a continuous vector line of geographical locations. This line is overlaid on the 1x1 km grid and every time the line passes through a cell, a value is assigned to the underlying cell. A line that intersects the cell two times will increment the cell value by two. The resulting dataset provides a reliable indicator of the frequency with which vessels belonging to different ship groups, length groups and gross tonnage groups have visited areas.

Data is available as WMS services that can be filtered by means of WMS dimensions to show possible combinations of ship groups, lengths and tonnage characteristics for the users chosen area of interest.

The first generation of the dataset is based on AIS data from Kystdatahuset—a service provided by the Norwegian Coastal Administration. Initially the data in Kystdatahuset cover a smaller area than Barentswatch, leaving e.g., parts of the management plan areas uncovered. This is presently being amended and within April ‘22, complete coverage is envisioned for all areas.

Tip: Conversion of vector lines to a grid cells involves generalization, and the length of the corresponding raster will deviate from the accuracy of the tracks the grid is based on. As a rule of thumb, multiplying the cell value with 0.7 would give an approximation of the number of kilometres.

This number of arrived at by assuming that for the most part, the segments of a ships track that intersects a grid cell will be a straight line. In a 1x1 km grid, each straight-line segment can be a maximum of 1.4 km long and at minimum >0. We may assume a normal distribution between >0 and 1.4km, resulting in 0.7km as an approximate number. For single cells, this will not be an exact number—but for larger areas consisting of multiple cells with a lot of traffic, the sum will provide an acceptable approximation.