Sky view factor analysis – implications for urban air temperature differences

This study identifies the use of the sky view factor (SVF) in urban climate studies. In addition, it relates air temperature differences to the SVF and examines these differences with respect to the height at which fish-eye photographs are taken for the calculation of the SVF. The study focuses on night-time air temperature patterns within the urban canopy using data collected during clear, calm nights from sixteen permanent stations and from car measurements. Fish-eye photographs taken at two levels (2 m above ground and at ground level) are compared and shown to be statistically different. The results of the study performed in Goteborg, Sweden, indicate a fairly strong relationship between air temperature and SVF. The permanent stations used indicate that it is better to use fish-eye photographs taken at ground level. The relationship is determined by means of regression analysis. The SVF variation in urban areas and the importance of SVF in relation to other central parameters such as thermal admittance are also discussed. Copyright © 2004 Royal Meteorological Society

[1]  M. Eriksson,et al.  Sky view factors in forest canopies calculated with IDRISI , 2001 .

[2]  Ingegärd Eliasson,et al.  Diurnal air temperatures in built-up areas in relation to urban planning , 2002 .

[3]  Ingegärd Eliasson,et al.  Urban nocturnal temperatures, street geometry and land use , 1996 .

[4]  C. S. B. Grimmond,et al.  Rapid methods to estimate sky‐view factors applied to urban areas , 2001 .

[5]  Lee Chapman,et al.  Rapid determination of canyon geometry parameters for use in surface radiation budgets , 2001 .

[6]  I. D. Watson,et al.  Simulation of surface urban heat islands under ‘ideal’ conditions at night part 2: Diagnosis of causation , 1991 .

[7]  I. D. Watson,et al.  The determination of view-factors in urban canyons , 1984 .

[8]  T. Oke.  Canyon geometry and the nocturnal urban heat island: Comparison of scale model and field observations , 1981 .

[9]  C. S. B. Grimmond,et al.  Surface description for urban climate studies: A gis based methodology , 1994 .

[10]  Lee Chapman,et al.  A method to assess the variation of urban canyon geometry from sky view factor transects , 2001 .

[11]  Lee Chapman,et al.  Sky‐view factor approximation using GPS receivers , 2002 .

[12]  Douw G. Steyn,et al.  The calculation of view factors from fisheye‐lens photographs: Research note , 1980 .

[13]  I. D. Watson,et al.  Graphical estimation of sky view-factors in urban environments , 1987 .

[14]  J. Mattsson,et al.  Canyon geometry, street temperatures and urban heat island in malmö, sweden , 1985 .

[15]  Kohji Yamashita,et al.  On relationships between heat island and sky view factor in the cities of Tama River basin, Japan , 1986 .

[16]  I. Karlsson.  Nocturnal Air Temperature Variations between Forest and Open Areas. , 2000 .

[17]  L. Chapman,et al.  Modelling of road surface temperature from a geographical parameter database. Part 2: Numerical , 2001 .

[18]  I. Eliasson,et al.  Spatial variations of incoming longwave radiationin Göteborg, Sweden , 2000 .

[19]  Ingegärd Eliasson,et al.  Spatial air temperature variations and urban land use — a statistical approach , 2003 .

[20]  C. Ratti,et al.  COMPARISON OF METHODOLOGIES FOR COMPUTING SKY VIEW FACTOR IN URBAN ENVIRONMENTS , 2001 .

[21]  W. R. Buckland,et al.  Statistical Theory and Methodology in Science and Engineering. , 1960 .

[22]  B. Holmer,et al.  Eine einfache operative Methode für die Bestimmung von „Sky View Factors“ in unregelmäßigen Straßenschluchten mittels Fischauge-Photos , 1992 .

[23]  Kristina Blennow,et al.  Modelling minimum air temperature in partially and clear felled forests , 1998 .

[24]  Deliang Chen,et al.  Influence of geographical factors and meteorological variables on nocturnal urban-park temperature differences--a case study of summer 1995 in Göteborg, Sweden , 1999 .