Erythemal Weighted Ultraviolet Trends Over Northern Latitudes

This study examines the distribution of long-term trends in ground-level erythemally-weighted ultraviolet-B (UVB, wavelengths 290-320 nm) exposures in the northern latitudes for the period 1979-1991 using measurements from the Nimbus 7 total ozone mapping spectrometer instrument. Zonal mean erythemal UV data show ~3-7% per decade increases in the mid-to-high latitudes. Analysis of the horizontal patterns in trends around summer months indicates that most of the regional increases (exceeding 6% per decade) in the northern hemisphere in the latitude range 30o - 40oN originate from the Pacific and Atlantic oceanic regions. Increases (also exceeding 6% per decade) in latitudes 40o - 60o appear to originate from the North American and Asian continents and also central Europe. Trends over the east Asian continent in high latitudes indicate increases exceeding 10% per decade for May-August.