According to NASA, the SWOT mission, a collaboration between NASA and the French space agency CNES, has tracked Earth's rivers swelling and shrinking from month to month over the course of a year. The mission found significantly less of a swing in river volumes than previous model-based estimates. A record drought in the Amazon likely influenced the tally made by the SWOT satellite.
The findings reveal new details about the underwater topography of the world's river channels. SWOT is the first satellite capable of surveying not only the ocean, but also nearly all the world's lakes and rivers with ultraprecision. SWOT does not measure the absolute volume of rivers, but it can track their width, surface height, and slope changing over time.
Traditionally, hydrologists have relied on models to calculate river storage changes, or they multiplied altimeter estimates of height by optical or radar estimates of width. SWOT measures both height and width at the same time using its sensitive Ka-band Radar Interferometer (KaRIn) instrument. 6 million observations from SWOT.
In aggregate, river volumes varied by almost 83 trillion gallons (313 cubic kilometers). That's about 28% less of a swing than the lowest previous estimates. The Amazon River varied more than any other during the year, gaining and losing more than 45 trillion gallons (172 cubic kilometers).
5 cubic kilometers). Possible explanations for the Nile's low variation include upstream damming and severe drought, along with challenges that come with learning to work with a new satellite instrument.