Ole Baltazar Andersen (DTU Space, Technical University of Denmark, Denmark)

Radar satellite altimeters enable the determination of the mean sea surface to centimeter
accuracy, which can be degraded in coastal areas because of the lack of valid altimetry observations
due to land contamination and the altimeter footprint size. In 2018, the National Aeronautics and
Space Administration launched ICESat-2, a laser altimetry mission equipped with the Advanced Topographic
Laser Altimeter System, providing measurements every 0.7 m in the along-track direction.
Taking into account the complexity of the Norwegian coastline, this study aims to evaluate coastal
observations from ICESat-2 in order to use it to update the existing mean sea surface for Norway,
NMBU18. We, therefore, determined the mean sea surface using only ICESat-2 observations and
compared it with mean sea level observations from 23 permanent tide gauges along the entire coast
and 21 temporary tide gauges in Norway’s largest and deepest fjord, Sognefjorden. We also included
two global mean sea surface models and NMBU18 for comparison. The results have shown that
ICESat-2 can provide more valid observations in the coastal zone, which can be used to
improve the mean sea surface model, especially along the coast.