The Antarctic ozone hole will break apart months earlier than usual this year, predicts the national meteorological centre of the Netherlands. Using satellite data from the European Space Agency (ESA), Henk Eskes from the Royal Netherlands Meteorological Institute (KNMI) has found that the depth of the ozone hole is much smaller than previously seen. 'This breakdown is occurring exceptionally early in the year, about two months earlier than normal,' says Mr Eskes, a KNMI senior scientist. 'The depth of the ozone hole this year also is unusually small, about half that recorded in 2001.' He predicts that the Antarctic ozone hole will first separate into two parts and then weaken even further afterwards. Despite the optimistic forecast, he warned that the possibility that one of the two remnants will strengthen and form a new ozone hole 'cannot be excluded.' Globally, there has been a slow decrease in the amount of ozone-depleting substances in the atmosphere. Mr Eskes believes this is due to international treaties to reduce their production. But, he added, 'this decrease is too slow to explain this year's weak ozone hole.' The explanation lies instead with the natural year-to-year variability of atmospheric circulation that influences the size and duration of the ozone hole, according to the Dutch scientist. The ozone hole is surrounded by a vortex of strong winds that block the exchange of air between polar and mid-latitude regions. During the South Pole's spring and summer, the temperature increases and the winds weaken. As a result, ozone-poor air inside the vortex mixes with the ozone-richer air outside, and the ozone hole dissipates. KNMI, the Dutch national research and information centre for climate, climatic change and seismology, uses data from ESA's Global ozone monitoring experiment (GOME) instrument onboard the ERS-2 satellite to generate daily global ozone analyses and nine day ozone forecasts. ESA, together with the European organisation for the exploitation of meteorological satellites (EUMETSAT), is also preparing a series of three satellites called MetOp that will carry follow on GOME instruments and guarantee at least 10 years of continued ozone monitoring from space, starting in 2005.