Abstract's details
Assessment of global and regional tidal models in coastal regions – a contribution to improve coastal altimetry retrievals
CoAuthors
Event: 2022 Ocean Surface Topography Science Team Meeting
Session: Coastal Altimetry
Presentation type: Type Poster
Contribution: PDF file
Abstract:
Because of the repeat period of the satellite altimetry missions (from 10 days for the Topex/Jason suite to more than one year for CryoSat-2), the high-frequency ocean tidal signals are aliased in the altimeter sea surface height measurements at periods that correspond to other ocean dynamics processes. To access the ocean circulation dynamics with the centimetric accuracy expected by the users, it is thus necessary to accurately remove the ocean tide signals from the altimeter measurements.
With amplitudes ranging from several centimetres to several metres, the ocean tide correction is one of the largest corrections to the altimetry sea surface heights on the shelves and in coastal regions. To remove this signal, global tidal models are used, such as FES2004, GOT4.10 and FES2014. However, these models still show large errors on the continental shelves. In some regions, the errors can reach tens of centimetres, as the amplitude of the tidal signals is large and more complex to model due to non-linear interactions between the tidal waves and the shallow bathymetry. With new and future satellite altimetry techniques (SAR, wide-swath) that enable to reach ever more coastal areas, and to resolve the ocean dynamics at ever finer scales, the need for accurate coastal tidal model solutions is salient.
Today, specific efforts are made to improve the tidal models in the coastal regions, thanks to high-resolution modelling and to the use of coastal observations (from altimetry and tide gauges) to constrain the models. Various models are thus available, at global and regional scales. These models are not always provided in the altimetry products, but they could be of high interest to locally improve the coastal altimetry sea surface height retrievals.
In the frame of the HYDROCOASTAL project funded by the European Space Agency, NOVELTIS performed an inventory of the available and most recent global and regional tidal models that could potentially be used as corrections for coastal altimetry data. The performance of these models was compared with a specific focus on coastal and continental-shelf regions where the tidal corrections are particularly critical for coastal altimetry observations. Finally, some recommendations were made about the models that perform best depending on the regions.
With amplitudes ranging from several centimetres to several metres, the ocean tide correction is one of the largest corrections to the altimetry sea surface heights on the shelves and in coastal regions. To remove this signal, global tidal models are used, such as FES2004, GOT4.10 and FES2014. However, these models still show large errors on the continental shelves. In some regions, the errors can reach tens of centimetres, as the amplitude of the tidal signals is large and more complex to model due to non-linear interactions between the tidal waves and the shallow bathymetry. With new and future satellite altimetry techniques (SAR, wide-swath) that enable to reach ever more coastal areas, and to resolve the ocean dynamics at ever finer scales, the need for accurate coastal tidal model solutions is salient.
Today, specific efforts are made to improve the tidal models in the coastal regions, thanks to high-resolution modelling and to the use of coastal observations (from altimetry and tide gauges) to constrain the models. Various models are thus available, at global and regional scales. These models are not always provided in the altimetry products, but they could be of high interest to locally improve the coastal altimetry sea surface height retrievals.
In the frame of the HYDROCOASTAL project funded by the European Space Agency, NOVELTIS performed an inventory of the available and most recent global and regional tidal models that could potentially be used as corrections for coastal altimetry data. The performance of these models was compared with a specific focus on coastal and continental-shelf regions where the tidal corrections are particularly critical for coastal altimetry observations. Finally, some recommendations were made about the models that perform best depending on the regions.