Reliably assessing chemical ozone-loss
One of the key objectives of the QUILT project was the improvement of existing stratospheric observations from ground-based, balloon and satellite platforms. The European satellite ERS-2 includes GOME, an instrument that comprises four spectrometers that obtain simultaneous measurements of sunlight reflection from the atmosphere and surface of the earth. It involves four spectral windows within the wavelength range of 240nm-790nm offering a moderate spectral resolution between 0.2-0.4nm. While the sun-synchronous satellite's orbit is at a nearly north-south direction, the GOME instrument sweeps in the perpendicular east-west direction. Three different spectral scans realised at one sweep correspond to three ground pixels within an area of 320km (east-west) by 40km (north-south). These pixels, a western, a central and an eastern lie next to each other. During a three-day period the whole surface of the Earth is covered and within one day, mapping towards the poles is completed. Aided by specialised techniques, such as the Differential Optical Absorption Spectroscopy (DOAS) raw data measurements contribute to the determination of important properties. For instance, the Slant Column Density (SCD) of key trace species may be derived from inferred differential absorption and knowledge of the cross sections. These trace species are O3 and halogen radicals, such as NO2, BrO and OClO. Research partners exploited existing satellite data for homogenisation of the GOME NO2, OClO and BrO time series. Employing suitable scientific algorithms consolidation of NO2, BrO and OClO data was performed and is available at: http://www.iup.physik.uni-bremen.de/gome/ and http://satellite.iup.uni-heidelberg.de/ . The reliability of the consolidated data sets can be evaluated by comparing these GOME NO2 and BrO columns with ground-based measurements and balloon measurements. More information on the QUILT project can be found at: http://nadir.nilu.no/quilt/index.php
