SWOT could prove to be a major improvement over measurements from previous satellites. “Instead of a ‘pencil beam’ moving along the Earth’s surface from a satellite, it is a wide swath. It provides much more information, much more spatial resolution and hopefully better coverage close to shores,” said Steve Nerem, a University of Colorado scientist who uses satellite data to study sea level rise and is not involved in SWOT. And KaRIn’s orbital mapping technology is an entirely new technique, he says. “It has never been tested from orbit, so it’s kind of an experiment. We are curious about the data.”
SWOT also has other instruments in its toolkit, including a radar altimeter to fill in the gaps between the data KaRIn collects, a microwave radiometer to measure the amount of water vapor between SWOT and the Earth’s surface, and an array of laser beam mirrors. measurements from the ground.
New satellite data is important because the future of sea level rise, flooding and drought could be worse than some experts previously predicted. “Within our satellite record, we’ve seen sea level rise along U.S. coasts rise rapidly over the past three decades,” said Ben Hamlington, a sea level rise scientist at JPL on the SWOT science team. The rate of sea level rise is actually accelerating, especially on the Gulf and East Coast of the United States. “The trajectory we’re on points us to the higher end of model projections,” he says, a point he made in a study published last month in the journal Communication Earth & Environment.
Hamlington sees SWOT as a boon for mapping rising seas and for researchers studying ocean currents and eddies, which affect how much atmospheric heat and carbon absorb oceans. The satellite will also help scientists who do modelling storm peaks– that is, when ocean water flows into the land.
The data from the new spacecraft will have some synergy with many other Earth observation satellites already in orbit. Those include Grace-FO from NASAthat explores subterranean water via gravitational fluctuations, NASA’s IceSat-2which examines ice caps, glaciers and sea ice, and commercial flood mapping satellites that use synthetic aperture radar to see through clouds. It also tracks other altimetry-equipped satellites, such as the US-European Jason-3, the European Space Agency’s Sentinel-6 Michael Freilich satellite, China’s Haiyang satellites, and the Indian-French Saral spacecraft.
Data from these satellites has already shown that some degree of sea level rise, extreme flooding, storms and droughts are already baked into our future. But we’re not doomed to climate catastrophe, Hamlington argues, because we can use this data to fend off the most extreme expected impacts, such as those prompting rapid glacier or ice cap to melt. “Reducing emissions takes some of the higher projections of sea level rise off the table,” he says. “Since catastrophic loss of ice sheets will only occur in very warm futures, if we can limit warming in the future, we can avoid worst-case scenarios.”