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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Record number 422524
Title Radiation balance at the surface in the city of São Paulo, Brazil: diurnal and seasonal variations
Author(s) Ferreira, M.J.; Oliveira, A.P. de; Soares, J.; Codato, G.; Wilde Barbaro, E.; Escobedo, J.F.
Source Theoretical and Applied Climatology 107 (2012)1-2. - ISSN 0177-798X - p. 229 - 246.
Department(s) Meteorology and Air Quality
Publication type Refereed Article in a scientific journal
Publication year 2012
Keyword(s) urban heat-island - land-surface - longwave radiation - solar-radiation - energy-balance - satellite data - st-louis - climate research - air-pollution - rural-areas
Abstract The main goal of this work is to describe the diurnal and seasonal variations of the radiation balance components at the surface in the city of São Paulo based on observations carried out during 2004. Monthly average hourly values indicate that the amplitudes of the diurnal cycles of net radiation (Q*), downwelling and upwelling shortwave radiation (SWDW, SWUP), and longwave radiations (LWDW, LWUP) in February were, respectively, 37%, 14%, 19%, 11%, and 5% larger than they were in August. The monthly average daily values indicate a variation of 60% for Q*, with a minimum in June and a maximum in December; 45% for SWDW, with a minimum in May and a maximum in September; 50% for SWUP, with a minimum in June and a maximum in September; 13% for LWDW, with a minimum in July and a maximum in January; and 9% for LWUP, with a minimum in July and a maximum in February. It was verified that the atmospheric broadband transmissivity varied from 0.36 to 0.57; the effective albedo of the surface varied from 0.08 to 0.10; and the atmospheric effective emissivity varied from 0.79 to 0.92. The surface effective emissivity remained approximately constant and equal to 0.96. The albedo and surface effective emissivity for São Paulo agreed with those reported for urban areas Europe and North America cities. This indicates that material and geometric effects on albedo and surface emissivity in São Paulo are similar to ones observed in typical middle latitudes cities. On the other hand, it was found that São Paulo city induces an urban heat island with daytime maximum intensity varying from 2.6°C in July (16:00 LT) to 5.5°C in September (15:00 LT). The analysis of the radiometric properties carried out here indicate that this daytime maximum is a primary response to the seasonal variation of daily values of net solar radiation at the surface.
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