85th AMS Annual Meeting

Wednesday, 12 January 2005
UV radiation in the southern seas in summer 2000
Gerd Wendler, Geophysical Institute, University of Alaska, Fairbanks, AK; and B. Hartmann
Poster PDF (1.8 MB)
During a cruise on the USCGC Polar Sea from Hobart, Tasmania to McMurdo, Antarctica, continuous radiation measurements were carried out; the global, UVA and UVB are being discussed in this paper. As we were performing the measurements on a moving platform, spot measurements can be incorrect, however, for 5 minutes means the validity was confirmed. Some of the main results are as follows:

The radiation level were more affected by cloudiness than by the change of latitude, as the higher solar elevations at lower latitudes were to a great extent balanced by longer day length at high latitudes.

The mean value of the clearness index Kt (total transmissivity) was found to be 0.51, a somewhat low value, which was caused by the high mean amount of cloudiness, mostly consisting of stratus. The mean clearness index was 0.74 for clear skies and 0.38 for overcast conditions, while individual values varied even more.

The UV radiation is related to the global radiation. However, correlation coefficients improved substantially when the analyses was done for different cloudiness classes.

Clouds produced the largest reduction for the global radiation, followed by UVA and the UVB. With other words, the relative intensity of UVB was influenced the least by clouds.

No good correlations between total ozone and UVB could be established, as the Antarctic ozone hole, which was well developed in spring, had been filled and values above 300 DU (Dobson Units) were observed during the whole passage.

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