Trends in total column , from the two longest serving stations in the northern (Arosa; 46.8° N, 9.6° E; circle) and the southern (Halley Bay; 75.5° S, 26.5° W; triangle) hemispheres, are plotted along with sunspot number (dashed line). The trends are calculated with respect to the 1979 value. Loss rates for Halley Bay are multiplied by 0.5 to fit in the plot.Reuse & Permissions