Altitude effect in UV radiation during the Evaluation of the Effects of Elevation and Aerosols on the Ultraviolet Radiation 2002 (VELETA-2002) field campaign

• Published in: Journal of Geophysical Research - Atmospheres Vol. 113; no. D23; pp. D23202 - n/a
• Main Authors: Sola, Y., Lorente, J., Campmany, E., de Cabo, X., Bech, J., Redaño, A., Martínez‐Lozano, J. A., Utrillas, M. P., Alados‐Arboledas, L., Olmo, F. J., Díaz, J. P., Expósito, F. J., Cachorro, V., Sorribas, M., Labajo, A., Vilaplana, J. M., Silva, A. M., Badosa, J.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 16-12-2008; Blackwell Publishing Ltd
• Subjects: Aerosols; Aerosols and particles; Air masses; Altitude; altitude effect; atmospheric aerosols; Atmospheric Composition and Structure; Atmospheric Processes; broad and narrow band measurements; Dust; Earth sciences; Earth, ocean, space; Exact sciences and technology; Instruments and techniques; Irradiance; Pollution; Radiation; Radiative processes; Radiative transfer; Spectra; stratospheric ozone; transmission and scattering; Ultraviolet radiation; urban and regional; UV Index; UVA and UVB radiation; Iberian Peninsula; Southern Europe; Europe; Spain; Africa, Sahara Desert; USA, California, Santa Barbara; broad and narrow band measurements; stratospheric ozone; UV Index; atmospheric aerosols; altitude effect; UVA and UVB radiation; wavelength; altitude; models; Solar zenithal distance; aerosols; radiative transfer; Summer; ultraviolet rays; air; troposphere; variability; trajectory; ozone; Mixed layer; optical properties; Air mass; irradiance; growth; Height; dust
• ISSN: 0148-0227; 2169-897X; 2156-2202; 2169-8996
• DOI: 10.1029/2007JD009742

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−1 at noon, while for the UVB (280–320 nm) band it reached 7–11% km−1. The AE for erythemally weighted irradiance ranged from 11 to 14% km−1 between the lowest and highest stations when it was calculated from spectral measurements.