Wind speed measurements and forest damage in Canton Zurich (Central Europe) from 1891 to winter 2007

Abstract

ABSTRACT:The most severe damage to forests in central Europe occurs during winter storms that are caused by Northern Hemispheric mid-latitude cyclones. These winter storms have caused several catastrophic windthrows during the past four decades. Amounts of forest storm damage are believed to be a function of both the size of the forest and the storm intensity. To test this hypothesis, the Zurich region (city and canton) was chosen because long-term climate observation data is available for the region. The relationships between forest attributes, wind speed and forest damage were explored by comparing data on forests and wind speed from 107 winters with forest damage. Storm damage was defined as the proportion of damaged forests with respect to the growing stock. The variables: daily wind run (91 years), daily maximum hourly average wind speed (107 years) and peak gust wind speed (74 years) were homogenized with respect to high wind speed and related to levels of forest damage.High maximum wind speed at the end of the 19th century and at the beginning of the 20th century was followed by low maximum wind speed in the 1940s, 1960s and 1970s. Since then, maximum values have increased. Gusts (extremes of the maximum wind speed) increased from the beginning of the recordings in 1933 and peaked in the early 1990s.Forest damage due to winter storms is best correlated with peak wind speed. Gusts exceeding 40 m/s and resulting in catastrophic windthrow have increased in recent winters.

An analysis of observed daily maximum wind gusts in the UK

“…However, some caution must be exercised in the interpretation of the decline in values post-1993, due to the extent of data available after the peak (PRECIS-Re terminates in 2001, and the observed data in 2005). In addition to the peak in DMGS values in the early 1990s, the frequency of extreme DMGSs appear to peak at the same time, a result in line with (Usbeck et al, 2010). These variations are likely driven by decadal variations in the large scale atmospheric circulation, with temporal variations in the NAO index correlating well with the inter-annual variations in DMGS and extreme DMGS.…”

“…However, this is generally restricted to issues of anemometer start-up speeds, and therefore redundant when considering DMGS, as these are, by definition, at the high end of the gust speed distribution. The difficulties of establishing a long, homogeneous record of windspeed, briefly highlighted here, are well understood, and further detailed by Best et al (2008), Usbeck et al (2010) and Tuller (2004) amongst others. Overall, the errors in the data appear to be less than 10%, the upper UK Met Office limit of error, which should be borne in mind during the interpretation of the results.…”

“…Long, continuous, homogeneous records of both mean windspeeds and gust speeds in Europe, though highly desirable, are largely unavailable (Rockel and Woth, 2007). A knowledge of the local characteristics of gust speeds is directly relevant, for example, to those involved in the design of structures (Ambrose and Vergun, 1995), sailing activities (Spark and Connor, 2004;Strefford, 2002), wind energy (Pryor et al, 2005;Sinden, 2007), the insurance sector (Klawa and Ulbrich, 2003;Leckebusch et al, 2007), aviation (Manasseh and Middleton, 1999), the forestry industry (Usbeck et al, 2010) and those considering the effects of wind driven rain (Choi, 1997).…”

Seasonal and annual variability of days with strong winds and wind damage in Krakow (Poland) during the period 2000–2007

“…The wind speed measurements from the Jagiellonian weather station point to strong winds as most frequent in winter when they are typically related to low pressure systems, Fig. 14 Zones of increased wind-damage risk in Kraków including, in particular, deep cyclones moving over central Europe. This is compatible with other research, including Usbeck et al (2010b). On the other hand, the call-out data from the Krakow Fire Department suggested more frequent damaging winds during summer when the high winds and gusts are linked to thunderstorms.…”

Changes in terrestrial near-surface wind speed and their possible causes: an overview

“…Knowledge of the local characteristics of gust wind is important, for example, to workers interested in the design of structures, the implementation of wind energy, and the forestry industry (Usbeck et al 2010a;Hewston and Dorling 2011).…”