Salar de Uyuni
As a result, the variation in the surface elevation over the area of Salar de Uyuni is less than normal to the Earth's circumference, and there are few square kilometers on Earth that are as flat. The surface reflectivity (albedo) for ultraviolet light is relatively high at 0.69 and shows variations of only a few percent during the daytime. The combination of all these features makes Salar de Uyuni about five times better for satellite calibration than the surface of an ocean. Using Salar de Uyuni as the target, ICESat has already achieved the short-term elevation measurement accuracy of below .