Measured and modelled contributions to UV exposures by the albedo of surfaces in an urban environment

Abstract

1 SummaryThe increases in the erythemal UV exposures to horizontal planes and to inclined planes over three surfaces that are found in an urban environment (water, concrete and sand) due to the albedo of these surfaces have been estimated. For the cloud free case, the additional daily estimated UV exposures to a horizontal plane have a maximum value of 222 (J m -2 ) ER , where the index after the unit is there to indicate that it refers to a biologically effective exposure. In comparison, the daily erythemal UV exposures over a year to a horizontal plane ranged from 425 to 8,321 (J m -2 ) ER . For a vertical receiving plane that is rotating about a vertical axis, the additional erythemal daily UV exposures for the sub-tropical latitude location of this research for the ranges of solar azimuth angles encountered over the days in each season ranged from 16 to 311 (J m -2 ) ER , 29 to 566 (J m -2 ) ER and 46 to 905 (J m -2 ) ER for water, concrete and sand respectively. The estimated error is ±20% and the calculations are based on clear-sky conditions. The additional erythemal UV averaged over each of the seasons was higher for the receiving plane inclined at 45 o below the horizontal plane. In a similar fashion, the vertical surface has the higher additional erythemal UV exposures compared to the surfaces inclined at an angle above the horizontal.2

Surface ultraviolet radiation

“…For water and most land surfaces the albedo is generally quite low (<5%) in the UV (e.g., Webb et al, 2004;Wendisch et al, 2004) and the UV ocean albedo is typically higher than the land albedo (Herman and Celarier, 1997). Sand surfaces can have higher albedo (Parisi et al, 2003). In general, spatial differences in land use (e.g., urban, agricultural, forest, etc.)…”

Reflected solar radiation from horizontal, vertical and inclined surfaces: Ultraviolet and visible spectral and broadband behaviour due to solar zenith angle, orientation and surface type

“…Irradiances on inclined surfaces affected by surrounding albedo have been previously explored [15][16][17]. Investigation of the biological effectiveness of the contribution to personal UV exposures due to the albedo of different horizontal and inclined surfaces has been investigated [18][19][20]. These effects are particularly important for outdoor workers' who should be aware of the contribution to UV exposures from such surfaces due to everyday working conditions [21].…”

“…Investigation of the UV irradiance received on vertical surfaces has been carried out [11,19,23]. Webb et al [24] determined a relationship between vertical and horizontal irradiances.…”

Effects of urban agglomeration on surface-UV doses: a comparison of Brewer measurements in Warsaw and Belsk, Poland, for the period 2013–2015

“…This is 4 times larger than the commonly used albedo of 0.03 over grass. Parisi et al (2003) found that over some non-shaded parts of the city with high albedo (e.g. concrete surface) there is Fountoulakis et al (2016) discussed factors important for the UV spectral variability in Thessaloniki.…”