Low Ozone in the Northern Hemisphere.

Recent measurements of the European GOME (Global Ozone Monitoring Experiment) instrument on board the ERS-2 satellite show unusual low total column ozone concentrations for this time of the year at high northern latitudes.

Figure 1 shows the distribution of total column ozone for 31 March, 1997 in the Northern Hemisphere as it was seen by GOME (left panel). The right panel gives the climatological mean of the zonal mean total ozone for March (CIRA 1996). Differences are clearly evident, especially at polar latitudes. The climatology shows high ozone concentrations (red color) around 400 - 500 DU towards the pole while GOME observes significant lower values (blue and green color) around about 250 - 300 DU. White areas indicate data gaps. The question if this can be interpreted in terms of an ozone hole similar to that in the Southern Hemisphere is still under investigation and cannot be answered at this moment.

Also interesting is the phenomenon of low ozone concentration above the North Sea. Figure 2 is a blow-up of figure 1, upper panel, and shows the situation in more detail. Obviously, this feature is due to transport processes of ozone low air from low latitudes to higher latitudes.

For further information please contact Thilo Erbertseder .