Ozone mini-hole over southwestern Spain during January 2004:: Influence over ultraviolet radiation

During the last decades, extremely low total ozone events of small spatial extension, named ozone mini-hole, have been reported in the Northern Hemisphere. A few ozone mini-hole episodes, which last only few days, were observed over southwestern Spain during 2004. In this work, these extreme events have been detected using TOMS satellite instrument. Additionally, the UV solar radiation was measured in three cities: Badajoz, Caceres, and Plasencia. The most intensive episode occurred on 10 January 2004 when total ozone amount values decreased to 189 - 200 DU. These values represent a decrease greater than 33% with respect to the mean values registered in these cities during 1996 - 2005. In this paper, firstly we analyse the origin of the ozone mini-hole episode which is related to two atmospheric dynamics processes. Secondly, the influence of these extreme events on ultraviolet radiation recorded under cloud-free conditions in southwestern Spain is described. A great increase in UV erythemal radiation measurement was recorded on 10 January 2004, between 43% and 75% with respect to values measured on 10 January 2003 and 10 January 2005.