Strong winds in South Africa : part 2 : mapping of updated statistics
Date
2013-08
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
South African Institution of Civil Engineering
Abstract
Although wind is the most important environmental action on buildings and structures in South
Africa, the last comprehensive strong wind analysis was conducted in 1985. The current wind
loading code is still based on the strong wind quantiles forthcoming from that analysis. Wind
data available for strong wind analysis has increased about five-fold, due to the employment of
automatic weather station (AWS) technology by the South African Weather Service. This makes
an updated assessment of strong winds in South Africa imperative.
Based on the estimation of strong winds as reported in the accompanying paper (see
page 29 in this volume), the spatial interpolation of 50-year characteristic strong wind values
to provide updated design wind speed maps is reported in this paper. In addition to taking
account of short recording periods and the effects of the mixed strong wind climate, the
exposure of the weather stations was considered and correction factors applied. Quantile values
were adjusted to compensate for the small data samples. The resultant design maps reveal
regions of relatively high and low quantiles, but with an improved relationship with physical
conditions compared to the previous analyses.
Consequently some significant differences in quantiles between the present and previous
analyses were found. The complexity of the resulting strong wind maps is not only the result
of the improved resolution of the larger number of weather stations, but also due to an
improved identification of the effects of physical factors such as the mixed strong wind climate
and topography. Guidance can also be derived for future updating, such as incorporating
accumulated observations and improved coverage by additional AWS in critical regions.
Description
CITATION: Kruger, A. C., Retief, J. V. & Goliger, A. M. 2013. Strong winds in South Africa : part 2 : mapping of updated statistics. Journal of the South African Institution of Civil Engineering, 55(2)46-58.
The original publication is available at http://www.scielo.org.za
The original publication is available at http://www.scielo.org.za
Keywords
Winds -- Measurement, Winds -- South Africa, Winds -- Speed, Winds -- Statistics -- South Africa
Citation
Kruger, A. C., Retief, J. V. & Goliger, A. M. 2013. Strong winds in South Africa : part 2 : mapping of updated statistics. Journal of the South African Institution of Civil Engineering, 55(2)46-58.