NSCAT will provide regular measurements of ocean surface wind velocity from space. NSCAT wind measurements cover 90 percent of the ocean surface each day, achieving nearly 100 percent coverage within three days. This map shows a global three-day average of wind speeds over the world's oceans. The continents appear in black. The uncalibrated data were taken from September 20 to 22, 1996. Color indicates wind speed; in this case, purple and blue denote low winds, green to yellow indicate moderate winds and orange to red stand for high winds. An usually high level of spring storm activity is visible as a broad yellow region in the southern hemisphere near Antarctica, in an area sailors refer to as "the roaring forties."