The total ozone maps are based on preliminary near-to-real time ground-based measurements received automatically at the WMO Ozone Mapping Centre and the. These include measurements from Brewer, Dobson, M-124 and SAOZ instruments. Total ozone values are given in Dobson Units. Maps of deviations represent total ozone deviations from the 1978-1988 level estimated using Total Ozone Mapping Spectrometer (TOMS) data.
Over areas with poor data coverage, depending on the period, adjustments are made according to TOMS on Nimbus-7, Meteor-3, ADEOS and Earth Probe satellites. Since 2005 in addition satellite measurements performed by OMI and SCIAMACHY sensors are used. Over the polar night area Dobson and Brewer moon observations and/or assimilated SCIAMACHY (TOSOMI) data are used courtesy of KNMI.
The mapping algorithm is similar to the one used by the World Ozone and Ultraviolet Radiation Data Centre. Data originators are invited to contact the WMO Ozone Mapping Centre and WOUDC if they wish to submit their data sets and participate in this project.