Data from the SWOT satellite has already exceeded expectations – find out why it is causing excitement among climate researchers, oceanographers and hydrologists
Results from mission are ‘far, far better than anyone anticipated’
A leading British scientist behind the SWOT climate satellite has hailed it as a ‘phenomenal flagship mission’ that is already providing exceptional new data about the world’s oceans and freshwater resources.
SWOT (Surface Water and Ocean Topography) was originally conceived as a way of mapping the globe’s freshwater resources as there was no consistent measurement scheme to collect and look at information. The mission is a partnership between National Aeronautics and Space Administration (NASA), Centre National D’Etudes Spatiales (CNES), the Canadian Space Agency (CSA) and the UK Space Agency.
UK expertise for SWOT includes Honeywell UK, the National Oceanography Centre, University of Bristol, Plymouth Marine Laboratory and University of Bangor.
18 months on from its December 2022 launch SWOT’s data are already driving new research and in exceeding expectations the data is opening up even more potential for new applications for research, services and climate products. Satellite altimetry to date has come from single ‘nadir’ radar beams with a footprint of several kilometres. The SWOT interferometric radar can map water elevations in 3D with unprecedented resolution of 50m or less over 60km swaths either side of the satellite, even through clouds.
Dr Paul Bell is the Lead Scientist for SWOT-UK at the National Oceanography Centre (NOC) where he is a Principal Research Scientist.
Wealth of information from pioneer instrument
He says: “There’s a huge wealth of information that everyone is getting very excited about. The data volumes involved in SWOT are absolutely enormous. Its data provides a global view in one consistent measurement scheme of freshwater resources, where they are growing or declining, and where the hotspots for that growth and decline are.”
Over the ocean, the measurements track circulation patterns that carry heat from the water surface down into deeper ocean and over vast distances, with heat moving between the water and atmosphere, playing a key role in regional climates. Over land SWOT monitors freshwater levels and their variability in lakes and rivers. It covers the globe every 21 days.
SWOT carries a pioneering instrument – the Ka-band Radar Interferometer (KaRIn) which is supplying images with an increase in resolution of up to 10 times that previously available. It uses two side antenna for a wider swath than previous satellites, totalling 120km. (For more on SWOT’s instrumentation see our SWOT Explainer.)
Paul says: “The data gives more understanding of ocean circulation, looking at little lumps and bumps on the sea surface – the little eddies and whirls from which scientists can establish currents that move heat around in the ocean.”
SWOT success already inspiring new missions
SWOT has a lifespan of a minimum three years. Paul adds: “It was always designed as an experimental mission but both NASA and ESA are already thinking about including some of its features in satellites of a more operational nature so this type of data will become a feature of future satellites – and that’s very important for scientists and practitioners – it’s a whole different investment scenario for potential users.
“SWOT was so complex, we wanted to know, can it work? How good is it? It has worked far, far better than anyone anticipated. Space agencies are already mopping up all of the knowledge and we are now going to see what level they can incorporate into future satellites and take on lessons learned.”
Following the UK’s validation work, carried out through the NERC and UK Space Agency-funded SWOT-UK project, over the Bristol Channel and Severn Estuary, Paul’s research is now focused on what SWOT data can tell us about movement between freshwater and seawater high up in river estuaries and in ports, and the implications for flood risk.
He says: “I’m looking at the data on tidal water levels far up in estuaries where we don’t usually have tidal gauges positioned, yet where sandbanks and channels are continually shifting and where there is a significant flooding risk.
Where to explore SWOT’s data
“Understanding the water levels in estuaries is very important but it has been very difficult to get water level information because they are affected by both freshwater and sea. Not only are these areas vital because many people live along estuaries and they are home to valuable agricultural land and industries, but river estuaries provide vital natural habitats for wildlife.”
NASA and CNES co-lead the mission, with the UK Space Agency and Canadian Space Agency playing a smaller role. Nevertheless UK Space Agency invested £12.22m and that involvement is inspiring the upcoming generation of experts. Paul says: “This is a catalyst for space and the UK. For today’s PhD and Master’s students it’s a chance to get their hands on a brand new type of data and let their imaginations run wild – and you don’t get that chance very often!”
Paul urges UK research groups and professional data analysts in the marine and hydrology sector to explore the data which is available through two platforms: CNES AVISO+ and NASA podaac. He says: “The UK has a strong set of small industries designing and building the hardware for satellites but we’ve also got a growing sector interested in using the data and pushing the boundaries of knowledge.”
For more information visit the SWOT-UK project page where you can subscribe to receive updates from NOC or email psb@noc.ac.uk