Publications (2)0 Total impact
Article: Climatology of ozone “mini‐hole” events and their influence on UV solar radiation in Barcelona (Spain)[show abstract] [hide abstract]
ABSTRACT: The total ozone column (TOC) shows a strong annual cycle, so the threshold to define its lower values is better characterized as deviations from local climatological mean levels. A complete analysis of the effects of low total ozone on the UV radiation measured in Barcelona (Northeast of Spain) is described in the present work. The ozone “mini‐holes” climatology in Barcelona, obtained from the daily ozone satellite data series (1978–2006), shows a seasonal behaviour with a maximum number of episodes in winter and early spring. Nevertheless there are a great number of events in the study area during September, when the UV irradiance reaching the Earth’s surface is still high and consequently the biological effects such as erythema could be more important. In fact, daily low ozone columnar contents in comparison with climatological means are detected throughout the year generally associated to weather systems passing. The deepest ozone “mini‐hole” reported in the area was in 2004. It lasted three days with a minimum on 10 January, when daily TOC was 40% lower than the January climatological mean. During those days under cloud‐free conditions the aerosol properties remained constant indicating that only low ozone levels were responsible of the increase in UV solar radiation. The erythemal irradiance at noon was 36% higher than the day before the extreme low ozone event. Although in absolute terms this increase is high, the erythemal effects are not so considerable because the UV levels in winter are low. On the other hand, the “mini‐hole” event observed in this area at the end of spring had more harmful biological consequences although the ozone decrease was not so great: on 20 April 2004, low ozone levels and high solar elevation favoured the increase in UVB radiation detected by an operative spectroradiometer. At 300 nm, the irradiance was 80% higher than the day before, declining to 31% at 305 nm. In this occasion the UV Index at 12 UTC increased in one unit.AIP Conference Proceedings. 03/2009; 1100(1):65-68.
Article: Altitude effect in UV radiation during the Evaluation of the Effects of Elevation and Aerosols on the Ultraviolet Radiation 2002 (VELETA-2002) field campaign[show abstract] [hide abstract]
ABSTRACT: 1] The Evaluation of the Effects of Elevation and Aerosols on the Ultraviolet Radiation 2002 (VELETA-2002) field campaign was designed to study the influence of aerosols and altitude on solar UV irradiance. The altitude effect (AE) was evaluated for UV irradiance under cloudless conditions by taking spectral and broadband measurements in SE Spain in the summer of 2002 at three nearby sites located at different heights (680 m, 2200 m, and 3398 m). A spectral radiative transfer model (Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART)) was also applied, mainly to evaluate the tropospheric ozone impact on AE. Results are related to the optical properties and air mass origin of the aerosols as determined by back-trajectory analysis. During the 1-week observing period of the campaign, there were two main synoptic situations with different air masses (polar maritime and tropical continental air mass associated with a Saharan dust event). The AE showed a high dependency on wavelength, solar zenith angle, and aerosols, although the growth of the mixing layer during the day also caused substantial AE variability. Saharan dust caused an increase in AE, especially in the UVB region and in the erythemal irradiance. In the UVA (320–400 nm) band the AE ranged 6–8% km À1 at noon, while for the UVB (280–320 nm) band it reached 7–11% km À1 . The AE for erythemally weighted irradiance ranged from 11 to 14% km À1 between the lowest and highest stations when it was calculated from spectral measurements.J. Geophys. Res. 01/2008; 113.
Universitat de Barcelona
Barcelona, Catalonia, Spain
- Departament d'Astronomia i Meteorologia