UV ground based measurements in Rio Gallegos, Argentina

CEILAP's Lidar Division has established an atmospheric remote sensing site in Rio Gallegos (51 deg 55[ S, 69 deg 14[ W) in the southern region of Argentina. SOLAR Campaign was held during 2005-2006. The main objectives of this experiment were to measure stratospheric ozone profiles and surface UV radiation in a subpolar region, where the influence of polar vortex and the Antarctic ozone hole are remarkable. This remote sensing site has lidar instruments and passive sensors to measure solar UV irradiance. In this paper we focused on passive remote sensing sensors and the Rio Gallegos erythemal irradiances reported during 2005-2006. Time evolution of UV index was derived from these measurements and the influence of ozone depleted air masses passing over over Rio Gallegos is highlighted in this paper. This Patagonian region is characterized by high cloud cover during the day that strongly changes the distribution of UV radiation that reaches the ground surface. For that reason some overpasses of ozone hole are masked by cloud cover avoiding the increase in UVB radiation. Reversely in same opportunities, cloud border increases the surface UV radiation. Both effects are analyzed in this work and the reduction or increase of ultraviolet radiation is quantified by comparing measurement and modeled UV radiation. In addition time evolution of daily UV exposures is presented.