Zmienność roczna współczynnika widoku nieba w centrum Łodzi

Annual variability of the sky view factor in the city center of Łódź

Summary: Green areas, especially shrubs and trees, influence urban climate due to the modification of the sky view factor (SVF) values. The influence varies in particular seasons (especially between winter and summer) and depends on the density of vegetation. The research was based on 1-year experiment (from 20 Oct., 2007 to 10 Nov., 2008), performed at four measurement points located in the central part of Łódź (Fig. 1, 2). Every two weeks, a digital fish-eye photo was taken at every point, however in winter the photo taking frequency was decreased. Digital photos were used to calculate the SVF values with BMSky-view software. For all measurement points, the maximum values of SVF were observed during winter, while minimum values occurred during summer. The difference between maximum and minimum values (?SVF) for all measurement points was over 0.272 (Table 1). Especially in winter and summer, some fluctuations of SVF were observed (Fig. 4) which might result from the impact of wind and snow cover on shrubs and trees, and accuracy of BMSky-view application. The obtained results suggest that the calculation of SVF based on digital photos techniques (Barring et al. 1985, Chapman et al. 2001, Holmer et al. 2001, Grimmond et al. 2001, Rzepa, Gromek 2006) are more reliable than others, used in urban climate models.

Słowa kluczowe: współczynnik widoku nieba, zdjęcia typu "rybie oko", algorytm Steyn'a, klimat miasta, Łódź

Słowa kluczowe (w języku angielskim): ky view factor, fish eye picture, Steyn's algorithm, urban climate

Prace Geograficzne, 2009, z. 122, s. 63-70.

Instytut Geografii i Gospodarki Przestrzennej UJ

ISSN 1644-3586

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