Preliminary UV, ozone and cloud comparison between Southern and Northern Hemisphere, sub-tropical latitude sites during 1996/1997

This paper compares 12 months of daily erythemal weighted ultraviolet (DUV) radiation, ozone and cloud cover data between two dissimilar, sub-tropical latitude sites during two months of 1996, and all of 1997, containing an o verlapping 10 month period. The sites were an urban Southern Hemisphere sit e (27.42 degreesS) and a Northern Hemisphere park land (29.3 degreesN). The daily averages for the respective 12 month periods were found to be 3.6 kJ /m(2), 27 DU (Dobson units) and 4 okta for the Southern Hemisphere site and 3.6 kJ/m(2), 282 DU and 3 okta for the Northern Hemisphere site. Although the maximum daily DUV level was higher by a nominal 12% at the Southern Hem isphere site compared to the Northern Hemisphere site, the Northern Hemisph ere National Park site had a daily DUV level comparable to that of the Sout hern Hemisphere urban site. The average ozone was higher by 2.5% at the Nor thern Hemisphere site compared to the Southern Hemisphere site and the clou d cover was higher by I okta at the Southern Hemisphere site. The higher cl oud cover, and its higher correlation to the changes in DUV at the Southern Hemisphere site, and the higher altitude of the Nor-them Hemisphere site, is believed to be the major causes for these similar daily average DUV leve ls. (C) 2001 Elsevier Science Ltd. All rights reserved.