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The study uses a Monte Carlo radiative transfer model to examine the sensitivity of the UV erythemal radiation (UVER) enhancement to broken liquid water clouds of the cumulus and stratocumulus type. The model uses monochromatic radiation at 310 nm corresponding approximately to the peak of the product between irradiance and the erythemal curve. All scattering, absorption, extinction coefficients, and spectral albedos are tuned to this wavelength. In order of importance, fractional cloud cover, the area of individual cloud patches, and cloud thickness exert a strong influence on the enhancement, with smaller contributions from cloud optical depth, cloud base height, and solar zenith angle. In order to produce realistic enhancements for our study area located in the Valencia region of Spain (39°30′N, 0°25′W), measurements were obtained from a Landsat image of the region in combination with a spectral Fourier transform model. The Monte Carlo model, as applied to the Fourier transform cloud distribution, produced satisfactory results compared to 1 year of measured UVER enhancement for the study region provided that fractional cloud cover was equal to or greater than 3/10. At smaller cloud fractions, the neglect of cloud patches less than 50 m × 50 m in area by the model created significant discrepancies.

Item Type:	Refereed Article
Keywords:	cloud optical depth, monte carlo, ultraviolet radiation, enhancement
Research Division:	Earth Sciences
Research Group:	Atmospheric Sciences
Research Field:	Atmospheric Radiation
Objective Division:	Environment
Objective Group:	Other Environment
Objective Field:	Environment not elsewhere classified
Author:	Nunez, M (Dr Manuel Nunez)
ID Code:	106743
Year Published:	2016
Web of Science® Times Cited:	2
Deposited By:	Geography and Spatial Science
Deposited On:	2016-02-18
Last Modified:	2017-10-30
Downloads:	51 View Download Statistics