By merging more than a decade of atmospheric data from European satellites, scientists have compiled a homogeneous long-term ozone record that allows them to monitor total ozone trends on a global scale and the findings look promising.
Scientists merged monthly total ozone data derived from the vertically downward-looking measurements of the GOME instrument on ESA's ERS-2 satellite, SCIAMACHY on ESA's Envisat and GOME-2 on the European Meteorological Satellite Organization's MetOp-A.
"We found a global slightly positive trend of ozone increase of almost 1% per decade in the total ozone from the last 14 years: a result that was confirmed by comparisons with ground-based measurements," said Diego G. Loyola R. who worked on the project with colleagues from the German Aerospace Center (DLR).
Ozone is a protective layer found about 25 km above us mostly in the stratospheric layer of the atmosphere that acts as a sunlight filter shielding life on Earth from harmful ultraviolet rays. The thinning of this layer increases the risk of skin cancer, cataracts and harm to marine life.
The ozone layer is not distributed evenly, with more changes occurring in the upper stratosphere. By collecting data while looking sideways (limb viewing) rather than vertically downwards, instruments are able to provide highly accurate measurements of the stratosphere.
A team of scientists around Ashley Jones and Jo Urban from Sweden's Chalmers University of Technology combined the limb measurements of US instruments SBUV, SAGE I+II and HALOE with data from OSIRIS, SMR and SCIAMACHY on the European satellites Odin and Envisat to analyse the long-term evolution of stratospheric ozone from 1979 to the present. These data show a decrease in ozone from 1979 until 1997, and a small increase since then.
"Our analysis shows that upper stratospheric ozone declines at northern and southern mid-latitudes at roughly 7% per decade during 1979
|Contact: Mariangela D'Acunto|
European Space Agency