Abstract's details
Towards validation of SWOT in the coastal zone: a radar altimetry and water level gauge case study in the Bristol Channel and Severn River-Estuary system
CoAuthors
Event: 2023 Ocean Surface Topography Science Team Meeting
Session: Regional and Global CAL/VAL for Assembling a Climate Data Record
Presentation type: Type Poster
Contribution: PDF file
Abstract:
The Bristol Channel and Severn River-Estuary system is highly dynamic with one of the largest tidal ranges in the world. The coastline surrounding these waters and upriver is covered by a network of water level gauges (WLGs), which has been continuously operational for a period of decades. This makes it an ideal area for the validation of new satellite altimetry sensors such as SWOT, that for the first time collects 2D maps of water level, and to explore quality of SWOT data in rivers and the coastal zone. The SWOT-UK project , a comprehensive programme of campaigns and multidisciplinary research for the UK contribution to the international SWOT Science Team validation work, is using this area for these purposes.
For the SWOT-UK project a set of WLG, CryoSat-2 and Sentinel-3 data has been gathered to validate water level and sea surface slope during the 90-day daily repeat SWOT CAL/VAL mission phase. Additional in-situ GNSS-IR instruments were deployed to fill gaps in the existing WLG network. These data were used to assess the consistency and quality of the WLG network, showing the random and systematic errors in the data, and develop a validation scheme for the 2D SWOT altimetry data in coastal and estuarine settings. This will highlight issues of how the coastal dynamics, hydrology and morphology affect the comparison of satellite altimetry and WLGs, and how these features may be seen in the 2D SWOT data. The slope along the satellite passes (across-channel), near-shore coastal dynamics and intertidal morphology have been seen to affect the comparison of satellite altimetry and WLG data, and these geographic characteristics are expected to influence the uncertainty in the comparison with the 2D SWOT data.
With the release of a small SWOT dataset to the CAL/VAL team, the validation data from Bristol Channel and Severn Estuary has been used for a preliminary assessment of the performance of these new 2D altimeter measurements. Cross-comparisons with in-situ and satellite data will be presented, with an exploration of the effect of coastal dynamics and morphology on these data, leading to an improvement of satellite altimetry in the coastal zone.
For the SWOT-UK project a set of WLG, CryoSat-2 and Sentinel-3 data has been gathered to validate water level and sea surface slope during the 90-day daily repeat SWOT CAL/VAL mission phase. Additional in-situ GNSS-IR instruments were deployed to fill gaps in the existing WLG network. These data were used to assess the consistency and quality of the WLG network, showing the random and systematic errors in the data, and develop a validation scheme for the 2D SWOT altimetry data in coastal and estuarine settings. This will highlight issues of how the coastal dynamics, hydrology and morphology affect the comparison of satellite altimetry and WLGs, and how these features may be seen in the 2D SWOT data. The slope along the satellite passes (across-channel), near-shore coastal dynamics and intertidal morphology have been seen to affect the comparison of satellite altimetry and WLG data, and these geographic characteristics are expected to influence the uncertainty in the comparison with the 2D SWOT data.
With the release of a small SWOT dataset to the CAL/VAL team, the validation data from Bristol Channel and Severn Estuary has been used for a preliminary assessment of the performance of these new 2D altimeter measurements. Cross-comparisons with in-situ and satellite data will be presented, with an exploration of the effect of coastal dynamics and morphology on these data, leading to an improvement of satellite altimetry in the coastal zone.
