Low Ozone in the Northern Hemisphere.
Differences are clearly evident, especially at polar latitudes.
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.