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The GOME ozone monitoring instrument

European Space Agency


page last modified:
23 January 2004



ERS orbit and GOME's global coverage

GOME measuring ERS-2 flies in a sun-synchronous polar orbit with an inclination of 98° at an altitude of 780 km. This results in an orbital period of about 100 minutes and a speed of the subsatellite point of 7 km/s and 14 orbits per day. The satellite crosses the equator at a local time of 10.30 h at the day side of the Earth, flying from North to South.

The full width of a normal GOME scanning swath is 960 km, which is divided in three ground pixels (named east, centre or nadir, and west, relative to viewing straight down), as the picture on the right illustrates. The scan measures 40 km in the direction of flight. The scanning width and the orbit specification combined means that GOME obtains global coverage in 3 days, as the figures below show, thus providing the opportunity to monitor relatively short-term processes that play a role in the Earth's atmosphere and are important for climate research.

 daily coverage
Coverage after one, two and three days by GOME's scan