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

Turner, J. and Parisi, A. V. and Turnbull, D. J. (2008) 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. Journal of Photochemistry and Photobiology, B: Biology, 92 (1). pp. 29-37. ISSN 1011-1344

[img]
Preview
PDF (Accepted Version)
Turner_Parisi_Turnbull.pdf

Download (176Kb)

Abstract

Ultraviolet (UV) radiation affects human life and UV exposure is a significant everyday factor that individuals must be aware of to ensure minimal damaging biological effects to themselves. UV exposure is affected by many complex factors. Albedo is one factor, involving reflection from flat surfaces. Albedo is defined as the ratio of reflected (upwelling) irradiance to incident (downwelling) irradiance and is generally accepted only for horizontal surfaces. Incident irradiance on a non horizontal surface from a variety of incident angles may cause the reflectivity can change. Assumptions about the reflectivity of a vertical surface are frequently made for a variety of purposes but rarely quantified. As urban structures are dominated by vertical surfaces, using albedo to estimate influence on UV exposure is limiting when incident (downwelling) irradiance is not normal to the surface. Changes to the incident angle are affected by the solar zenith angle, surface position and orientation and surface type. A new characteristic describing reflection from a surface has been used. The ratio of reflected irradiance (from any surface position of vertical, horizontal or inclined) to global (or downwelling) irradiance (RRG) has been calculated for a variety of metal building surfaces in winter time in the southern hemisphere for both UV and visible radiation spectrum, with special attention to RRG in the UV spectrum. The results show that the RRG due to a vertical surface can exceed the RRG due to a horizontal surface, at smaller solar zenith angles as well as large solar zenith angles. The RRG shows variability in reflective capacities of surface according to the above mentioned factors and present a more realistic influence on UV exposure than albedo for future investigations. Errors in measuring RRG at large solar zenith angles is explored, which equally highlights the errors in albedo measurement at large solar zenith angles.


Statistics for USQ ePrint 4285
Statistics for this ePrint Item
Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Deposited in accordance with the copyright policy of the publisher.
Depositing User: Assoc Prof Alfio Parisi
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 25 Jul 2008 06:06
Last Modified: 29 Aug 2014 06:26
Uncontrolled Keywords: albedo; RRG; vertical surfaces; UV radiation; visible; solar zenith angle; skin cancer; erythema
Fields of Research (FOR2008): 01 Mathematical Sciences > 0102 Applied Mathematics > 010202 Biological Mathematics
02 Physical Sciences > 0205 Optical Physics > 020599 Optical Physics not elsewhere classified
04 Earth Sciences > 0401 Atmospheric Sciences > 040103 Atmospheric Radiation
Socio-Economic Objective (SEO2008): E Expanding Knowledge > 97 Expanding Knowledge > 970106 Expanding Knowledge in the Biological Sciences
Identification Number or DOI: doi: 10.1016/j.jphotobiol.2008.03.006
URI: http://eprints.usq.edu.au/id/eprint/4285

Actions (login required)

View Item Archive Repository Staff Only