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c:/dev/skygeo/src/iso2stac/stac_output_dynamic/collection-norwegian_mapping_authority/collection.json
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c:/dev/skygeo/src/iso2stac/stac_output_dynamic/collection-norwegian_mapping_authority/64453561-4ee4-4ea0-86d2-c203061f1ad9/64453561-4ee4-4ea0-86d2-c203061f1ad9.json
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c:/dev/skygeo/src/iso2stac/stac_output_dynamic/collection-norwegian_mapping_authority/collection.json
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The chapter Waves and weather on the Norwegian coast with a description of hazardous areas was first published in Den norske los vol. 1 in the edition published in 1981 and is mainly taken from the research project Ships at sea from 1978 -1980. The purpose of the project was to improve the safety of smaller ships in heavy seas. The maps were produced by Kjeldsen & Myrhaug at the Norwegian Institute of Marine Technology Research in 1978 for the report. The initiative for the project Skip i sjøgang was at the Norwegian Ship Research Institute (now MARINTEK) with department engineer Terje Nedrelid as project manager.  It was funded by the Norwegian Maritime Authority, the Norwegian Fisheries Research Council and the Norwegian Research Council for Science and Technology. 
The project showed by mathematical calculations that these areas concentrate wave energy due to their local topography and current conditions. Under certain weather conditions, the waves will be steeper inside these areas than further out in deep water. As an important part of the work to map typically dangerous areas along the coast, an extensive survey was conducted among pilots and fishermen where they were asked to describe the wave conditions in the places they believed to have unusually rough seas. 
Responses were received from people living along the entire coast, and 19 dangerous areas were referred. 
The list was expanded in the following years with 5 new areas. The report specified that the list is not exhaustive and that these are not the only areas along our coast where such phenomena occur. But these are in areas with heavy traffic and many of them are in the middle of the shipping lane. The areas marked in maps with textual descriptions are essentially the source for the further modernized maps in further publication of volume 1 up to 2018.

Words and phrases in the dataset:
- Refraction is a physical phenomenon in which a wave movement changes direction in the transition from one medium to another. The term is used in nautical sciences/meteorology to refer to wave formations.
-Breakers occur mostly in shallow water. When a wave touches the bottom, the energy will be pushed upwards. We see it on the beach, where the burns rise and roll in from seemingly calm seas outside. However, the phenomenon can also occur in deep water by merging several waves to create an extra high and steep wave with a high energy content. The water is accelerated to about 3 g and the top shoots forward and strikes down into the valley in front.  The rushing flood closes an air pocket inside it, creating large and dangerous shock pressures. Such a burn is very large and can even lead to the breakdown of large ships.
The digitization has been done by georeferencing the maps using modern coastal contour and digitizing the areas on screen with the maps as backgrounds. The positional accuracy must be considered approximate. But given the fuzzy nature of the areas, in terms of source and purpose, it is considered sufficient to convey that particular care should be taken in areas with dangerous waves.
The accompanying text for the 24 areas is entered as attributes.
Kyst og fiskeri Samferdsel Samfunnssikkerhet Vær og klima Norway's coastel areas Northsea, norwegian areas Norwegian Sea Skagerrak Barents Sea Caution Waves Warning dangerous waves Barentswatch wave warning infoMapAccessService National
The service contains areas with information describing areas with dangerous waves along the Norwegian coast. It warns against breakers and refraction areas at special wind directions and that information on weather and wave heights should be obtained from available services such as https://www.barentswatch.no/bolgevarsel/
The areas have heavy traffic and many of them are in the middle of the shipping lane.
The dataset is based on the chapter on Dangerous waves in the historical norwegian sailing direction Den norske los volume 1. 
The areas described are: 1. Varanger 2. Tanafjorden 3. Nordkinnhalvøya 4. Ingøy 5. Lopphavet 6. Kvaløy 7. Røst 8. Vestfjorden 9. Folda 10. Smøla 11. Hustadvika 12. Godøya 13. Stadhavet 14. Stavfjorden 15. Sognesjøen 16. Vikingbanken 17. Sletta 18. Skotemedgrunnen 19. Siragrunnen 20. Hidra 21. Lista 22. Ryvingen 23. Skagerrak 
24. Svenner
Areas with dangerous waves along the Norwegian coast