SWOT: Pushing the Boundaries Beyond What's Possible (2024)

Undergraduates: Sophia Harvey, Talia Benjamin, Kate Merrin, Jackqueline Wilson

Faculty Advisor: Drew Coleman
Department: Earth, Marine, and Environmental Sciences

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NASA’s Surface Water and Ocean Topography (SWOT) mission aims to provide a comprehensive analysis of the globe’s surface water. The SWOT satellite measures the height of nearly all water surfaces worldwide every 21 days and is expected to identify rivers and streams 30 meters or wider. However, upon analyzing some of SWOT’s recent data and observing its unexpected accuracy, SWOT researchers questioned if it could potentially survey narrower-than-expected rivers. In October 2023, SWOT made its regular orbit and passed over the Owens River, which is located in eastern California, beginning in the Sierra Nevada mountain range and flowing about 120 miles southwest to Owens Lake (which is now dry). The Owens River is approximately 6-15 meters wide on average (less than half of SWOT’s expected identification capacity) and flows through a relatively unobscured landscape, providing a prime test subject to analyze SWOT’s potential higher-than-predicted accuracy. As part of our First-Year Seminar in EMES 72H, we determined the water surface elevation of the Owens River at three locations and compared our data with SWOT. For two of the ground-truthing locations, the average height of the water surface elevation data points SWOT picked up had a discrepancy of less than 1 meter compared to our data and 3 meters at the other. Additionally, SWOT could accurately approximate the river’s slope, yielding a 0.1 m/km discrepancy. While more data must be collected, these findings suggest SWOT may be capable of surveying narrower rivers than initially expected.