The surface winds of Sweden during 1999–2000

Abstract

This study aims at increasing our understanding of the regional wind climate in Sweden. Spatial and temporal patterns of the surface winds are presented for the years 1999-2000. Annual mean wind speeds range between 2 and 5 m/s with high values at exposed mountainous sites and on islands off the coast. Combining wind speed and direction into mean wind velocities shows that flow conditions are stronger and more coherent in space in southern Sweden than in central and northern Sweden. The spatial scale, defined as the distance between stations when the correlation for wind speed drops to ∼0.37, was determined by pairwise correlations between all possible station pairs. Scales range from 38 to 530 km for wind speed and from 40 to 830 km for wind direction depending on the region. They tend to be smaller in central and northern Sweden, where the more pronounced relief has a larger influence on the local wind conditions. The strength and the timing of the annual and diurnal wind speed cycle have been estimated for each station. Amplitudes of the annual cycle are greater at exposed sites and correlate generally well with annual mean wind speeds. Monthly mean wind speeds peak in winter in southern Sweden, but peak in other seasons in the remaining regions. In winter, weaker pressure gradients over northern Sweden and surface-near temperature inversions contribute to weaker surface winds. Diurnal cycles vary in strength between summer and winter. Compared to the last normal climate period , 1999-2000 is characterized by the increased occurrence of westerly and southerly geostrophic flow.

Seasonal and diurnal variations of wind parameters at Pakri

“…While there is almost no dependence of the wind speed on the measurement time in winter and a weak maximum becomes evident at midday in autumn, there is a strong daily cycle in spring and summer. Such a variation is similar to that observed at Swedish wind measurement sites [ 19 ].…”

Multi-variable bias correction: application of forest fire risk in present and future climate in Sweden

“…This can be attributed to the parameterisation utilised in unresolved orography, and uncaptured small-scale features, for instance, the influence of hills, lakes, valleys, etc. Furthermore, the incorrect seasonal wind speed variation generated by the climate model implies that the RCA3 model captures large-scale forcing well, but no other influencing processes such as seasonal variations and atmospheric stability over land and water that largely influence the wind speed (Achberger et al, 2006). For inland stations, such as Edsbyn, the seasonal variation in stability over the land is smaller than that over the sea, which reduces the seasonal wind speed variation compared to stations close to the sea (Achberger et al, 2006).…”

“…Furthermore, the incorrect seasonal wind speed variation generated by the climate model implies that the RCA3 model captures large-scale forcing well, but no other influencing processes such as seasonal variations and atmospheric stability over land and water that largely influence the wind speed (Achberger et al, 2006). For inland stations, such as Edsbyn, the seasonal variation in stability over the land is smaller than that over the sea, which reduces the seasonal wind speed variation compared to stations close to the sea (Achberger et al, 2006). However, it seems that Edsbyn was modelled as a coastal location where winter wind speed is enhanced because of less stably stratified atmosphere over water and the stronger pressure gradient in winter.…”

Meteorological application of wind speed and direction linked to remote sensing images for the modelling of sand drift potential and dune morphology

“…Although the most erosive winds (≥ 13.9 m·s −1 ) were identified during winter, the higher precipitation and less evaporation (Table ) and probably the greater threshold velocity during this season make the estimations more difficult. In fact, atmospheric humidity is an important factor weakening the potential for sand drift during winter (Achberger et al ., ; Bernhardson et al ., ). Bärring et al .…”