This movie shows a sequence of daily images of the southern hemisphere using an orthographic projection looking down on the Earth from 60 degrees south latitude. The ozone hole is indicated by ozone values less than 225 Dobson Units (the violet colors). The black circle in the middle is due to polar night, when TOMS cannot measure ozone. Notice that it's size decreases and then it disappears as the apparent position of the sun crosses over the equator (signalling the start of spring in the southern hemisphere) and more and more of Antarctica becomes sunlit. The other black gaps are due to the fact that Earth Probe is in a 500 kilometer orbit and cannot, therefore, provide full daily global coverage for ozone measurements within 60 degrees of the equator. The discontinuity that is sometimes seen at the international date line (180 degrees longitude) is due to the fact that data on the east side of the line (negative longitudes) are taken up to 24 hours later than the west side of the line (positive longitudes). Due to a problem with the satellite, there is no data for 17-November-97 and 18-November-97. |