More than 75 percent of the world's population relies on drinking water from lakes, rivers, and other surface sources. The Surface Water Ocean Topography mission brings together two communities focused on a better understanding of the world's oceans and its terrestrial surface waters. Our understanding of the oceanic circulation at mesoscales and smaller, where most of the ocean's kinetic energy and its dissipation takes place, is poor. Likewise, the role of internal tides as sources of mixing as well as coastal processes such as upwelling, jets, and fronts are not well understood. Given our basic need for fresh water, the most important hydrologic observations that can be made in a basin are of the temporal and spatial variations in water volumes stored in rivers, lakes, and wetlands.
The Jason series of satellites has gathered groundbreaking data on global oceans using global oceans using radar altimetry. However, the data's resolution is not sufficient to assess water levels on rivers and near coastlines. SWOT will extend the Jason record and analyze water surfaces over both land and ocean at much higher spatial resolution, using a suite of instruments that includes an interferometer, a microwave radiometer, and a radar altimeter. SWOT will produce the first remotely sensed estimates of water storage in lakes, reservoirs and wetlands across the world. Its vertical accuracy will be a few centimeters, averaged over areas of roughly a square kilometer. In many locations, these will be the first such data ever available, serving as a boon to water managers as well as researchers studying river and water-storage dynamics.