The Surface Water Ocean Topography (SWOT) mission brings together two communities focused on a better understanding of the world's oceans and its terrestrial surface waters. U.S. and French oceanographers and hydrologists have joined forces to develop this new space mission to make the first global survey of Earth's surface water, observe the fine details of the ocean's surface topography, and measure how water bodies change over time. SWOT was one of 15 missions listed in the 2007 National Research Council Decadal Survey of Earth science as missions that NASA should implement in the coming decade.
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The SWOT satellite mission with its wide-swath altimetry technology is a means of completely covering the world's oceans and freshwater bodies with repeated high-resolution elevation measurements. SWOT is a truly multi-disciplinary cooperative international effort.
Given our basic need for fresh water, hydrologic observations of the temporal and spatial variations in water volumes stored in rivers, lakes, and wetlands are extremely important. Unfortunately, our knowledge of the global dynamics of terrestrial surface waters and their interactions with coastal oceans in estuaries is very limited. By measuring water storage changes in all wetlands, lakes, and reservoirs and making it possible to estimate discharge in rivers more accurately, SWOT will contribute to a fundamental understanding of the terrestrial branch of the global water cycle. SWOT will also map wetlands and non-channelized flow.
Where most of the ocean's kinetic energy and its dissipation takes place--at scales shorter than 100 km--our understanding of the oceanic circulation is poor. Circulation at these scales is responsible for transporting half of the heat and carbon from the upper ocean to the deep ocean. Knowing more about this process is critical for understanding global climate change. SWOT will provide high-spatial resolution, global measurements of ocean surface topography. These measurements will improve ocean circulation models leading to better prediction of weather and climate as well as variations in ocean currents important for navigation, fisheries, and offshore commercial operations.
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