Thesis defence M. Kleinherenbrink: sea level

12 November 2018 12:30 - Location: Aula, TU Delft - By: webredactie

Consistent estimates of sea level and vertical land motion based on satellite radar altimetry. Promotor: Prof.Dr.-Ing. Habil R. Klees (CiTG).

Sea level is changing due to variations in ocean mass and density. Long-term trends in ocean mass are associated with the loss of land ice, while long-term trends in ocean density are connected to the warming of the ocean. Sea level change is therefore one of the consequences of a changing climate. Superpositioned on the long-term signals, significant interannual variability is present, which is mostly caused by ocean dynamics. On regional scales, these signals are typically an order of magnitude larger, making it often difficult to extract the long-term behavior.

To understand processes that drive sea level changes, budgets are used. This requires the estimation of density changes from in-situ temperature and salinity measurements with Argo floats, and the estimation of ocean mass changes from satellite gravimetry. If the sum of the steric and mass components equals the total sea level estimated from satellite altimetry data within uncertainties the budget is closed. The first part of this thesis deals with budget closure in unprecedented small regions in the North Atlantic Ocean and the Tropical Asian Seas.

Inseparable from sea level change is vertical land motion. Firstly, because the redistribution of water masses causes the Earth to deform and secondly, because terrestrial observing systems like tide gauges observe sea level changes relative to the land, while spaceborne systems observe sea level changes relative to the center of the Earth. By differentiating the tide-gauge and satellite altimetry observations vertical land motion is estimated, which is compared with GPS-derived trends. The second part of this thesis focuses on vertical land motion computations and potential drifts in the observing systems.

More information?

For access to theses by the PhD students you can have a look in TU Delft Repository, the digital storage of publications of TU Delft. Theses will be available within a few weeks after the actual thesis defence.