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Sensitivity of UVER enhancement to broken liquid water clouds: a Monte Carlo approach
journal contribution
posted on 2023-05-18, 17:11 authored by Manuel NunezManuel Nunez, Marin, MJ, Serrano, D, Utrillas, MP, Fienberg, K, Martinez-Lozano, JAThe 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.
History
Publication title
Journal of Geophysical Research: AtmospheresVolume
121Pagination
949-964ISSN
2169-897XDepartment/School
School of Geography, Planning and Spatial SciencesPublisher
Amer Geophysical UnionPlace of publication
United States of AmericaRights statement
Copyright 2016 American Geophysical UnionRepository Status
- Open