Improved method of ultraviolet radiation reflection measurement for non-horizontal urban surfaces

Abstract

The technique of ultraviolet reflection ratio measurement is modified from the traditional albedo measurement in order to compensate for unusual inflation of the reflection ratio found previously in non-horizontal surface ultraviolet reflection studies. Data collected to test this method of reflection ratio collection shows there is significant reduction in the inflation. In order to collect UV reflection ratio data on non-horizontal surfaces that can be comparable to differently oriented planar surfaces, the sun and the sensor's positions during the measurement process are equally important, which leads to this new method of reflection measurement for non-horizontal surfaces.

Influence of reflected UV irradiance on occupational exposure from combinations of reflective wall surfaces

“…Previous published studies have shown that time of day and season are important to the reflective capacity of the surface types investigated. 22,23 The atmospheric conditions for the wall data as reported in Turner and Parisi 21 was clear with low to no clouds. The ozone was 255-259 DU (zinc aluminium) and 252-275 DU ( pale green) as provided by the U.S. National Aeronautics and Space Administration's Ozone Monitoring Instrument.…”

“…2 and 3 when considering the influence of a wall or corner and this is confirmed through statistical significance (Table 1), with the statistical significance increasing when focusing on facial sites that are more influenced by the surrounding surfaces. Previous work on understanding UV reflection from non-horizontal surfaces 22,23 suggests that pale green ( paint) coated steel surfaces reflect UV radiation differently to zinc aluminium coated steel surfaces. This is likely due to more diffuse reflection occurring rather than specular reflection, where the angle of reflected irradiance does not depend on incident irradiance, as a result of the paint molecules causing the effect of backscatter to incident UV radiation.…”

Investigation of correlation of broadband UVA reflection to broadband visible reflection for a variety of surfaces in the built environment

“…Some natural surfaces can be assumed to be an approximate Lambertian surface, but many surfaces, both natural and built, tend to show variation of reflectance dependent on the incident irradiance angle. Previous work has already shown a number of building materials reflect anisotropically, and therefore indicates the surfaces are not predominantly Lambertian [34,35]. In computer modelling studies of reflectance from surface, bidirectional reflectance is more pronounced on specular surfaces compared to diffuse surfaces with the difference described using clear spikes or lobes observed [42].…”

“…Reflectance of roofing materials have been documented, but only for horizontal orientations or else conducted in the lab [32,33]. In the last decade, the authors have investigated reflectance from non-horizontal surfaces in the built environment (in the field) to compare to horizontal surfaces [34][35][36][37][38]. The reflectance from primarily vertical surfaces raised issues with terminology, such as the usage of reflectance versus albedo.…”

“…The latter definition of albedo provided above does not entail a measurement that is appropriate for vertical surfaces. Turner and Parisi [34] show that using down-welling irradiance (all irradiance incident from a hemispherical range of 180°) created artificially inflated reflectance values due to the orientation of the surface (vertical) and the position of the sensor (with non-sun normal measurements). Reflectance ratios exceeded the maximum of 1.0 reflectance using the albedo definition of up-welling and down-welling irradiances, when measured in the field.…”