Foto: Valdemaras D., Pexels

Reliable observations to study sea-level variations along the coast of Norway

Both hydrographic stations and satellites provide reliable observations to study changes in sea level along the Norwegian coast on a month-to-month basis, according to a new article by Fabio Mangini and other researchers from the Nansen Center and Sweden.

Having reliable information on sea level is especially relevant for coastal communities. Measuring and understanding the variations is therefore an important task. The sea level in a region can change over the course of years, but it also varies over shorter times, such as months.

When measuring the changes in the sea level, researchers distinguish between two components contributing to the total change – the mass and the steric components. The mass component is altered when the amount of water in a location changes, whereas the steric component is dependent on the density of water, thereby affected by temperature and salinity.

The recent publication by Fabio Mangini and his colleagues focus on the mass component, along the coast of Norway. They set out to investigate if both hydrographic stations and remote sensing instruments can be used to get reliable information on sea-level variations on a month-to-month basis. Along the coastline of Norway, which is thousands of kilometers long, there are only eight such hydrographic stations. They can measure changes in the sea level, but can they provide reliable estimates for such a long coastline? And are satellites circling the globe, doing the same thing but in a different way. Two satellite missions especially, GRACE and GRACE-FO, have caught the interest of Fabio Mangini and his colleagues. These two are generally considered to not be reliable in coastal areas, but they set out to see if this is true.

Fabio Mangini and his colleagues found that even though there are only eight hydrographic stations along the Norwegian coast, the data they measure is reliable to study the overall sea-level variations along the coast of Norway. And moreover, they found that the satellite-based information from GRACE and GRACE-FO are just as reliable. Both sources can be used to study the variability of the sea level in the region, and the findings suggest that GRACE and GRACE-FO satellite mission data can also be used to study other coastal areas, not just Norway’s coast. This has important implications for studies of sea-level variations in other parts of the world especially where coastal instruments are absent.

Photo by Valdemaras D., Pexels

Variasjoner i havnivået

På et bestemt sted varierer havnivået over både kort og lang sikt. I korte tidsrom, som for eksempel noen dager, har lufttrykk og vind en effekt på havnivået. Når man ser på lengre tidsrom, som for eksempel ett år, har årlige variasjoner i lufttrykket og vannets tetthet som varierer med vanntemperaturen stor påvirkning på havnivået.


Scientific Reports:
«Detection and attribution of intra-annual mass component of sea-level variations along the Norwegian coast»