Trends of daily peak wind gusts in Spain and Portugal, 1961-2014

• Given the inconsistencies of wind gust trends under the widespread decline in near-surface wind speed (stilling), our study aimed to assess trends of observed daily peak wind gusts (DPWG) across Spain and Portugal for 1961-2014 by analyzing trends of (i) the frequency (90th percentile) and (ii) the magnitude (wind speed maxima) of DPWG. Wind gust series were homogenized on a daily basis, using MM5-simulated series as reference, resulting in 80 suitable station-based data sets. The average DPWG 90th percentile frequency declined by -1.49ddecade(-1) (p<0.05) annually. This showed marked seasonal differences: decreasing in winter (-0.75ddecade(-1); p<0.05) and increasing in summer (+0.18ddecade(-1); p>0.10). A negligible trend was calculated for the annual magnitude of DPWG (-0.005ms(-1) decade(-1); p>0.10), with distinct seasonality: declining in winter (-0.168ms(-1) decade(-1); p<0.10) and increasing in summer (+0.130ms(-1) decade(-1); p<0.05). Combined, these results reveal less frequent and declining DPWG during the cold semester (November-April) and more frequent and increasing DPWG during the warm semester (May-October). Large-scale atmospheric changes such as the North Atlantic Oscillation Index (negative correlations similar to-0.4--0.6; p<0.05) and the Jenkinson and Collison scheme (positive correlations mainly with Westerly regime: similar to+0.5-0.6; p<0.05) partly account for the decadal fluctuations of both frequency and magnitude of DPWG, particularly in winter. However, the North Atlantic Oscillation index-DPWG relationships are smaller in spring, summer, and autumn (similar to-0.1--0.2; p>0.10), especially for the frequency, suggesting the role of local-to-mesoscale drivers.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

long-term trends

daily peak wind gusts

atmospheric circulation

Spain and Portugal

field significance

speed trends

europe

homogenization

maximum

storms

netherlands

iceland

period

nao

Meteorology & Atmospheric Sciences

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)