Faculty of Physics - University of Bucharest

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2024-11-22 2:04

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Conference: Bucharest University Faculty of Physics 2013 Meeting

Section: Atmosphere and Earth Science; Environment Protection

Title:

Seasonal changes in wind speed in Romania

Authors:

Lenuta Marin (1,2) , Marius-Victor Birsan (1), Alexandru Dumitrescu(1)

Affiliation:

(1) National Meteorological Administration, Bucharest, Romania.

(2) Faculty of Physics, University of Bucharest, Bucharest, Romania.

E-mail

lenuta.marin@meteoromania.ro

Keywords:

Wind trends, Mann-Kendall, wind speed, climate change, Romania

Abstract:

Changes in near-surface wind speed have important implications in several disciplines, like wind energy generation, wind erosion, wind transport of pollen and seeds, wind transport of pollution and associated impacts on human health.Previous hydroclimatic studies on Romania – at country or regional scale – have focused on changes in precipitation, temperature, cyclonic activity, snow, streamflow, droughts, and floods. This paper presents the first 50-year analysis of seasonal trends in wind speed in Romania. The data used in this study belongs to Meteo Romania (National Meteorological Administration). The time series consist in continuous records over the 50-year study period, over the period 1961-2010, on annual and seasonal basis.. Stations with records with less than 10% missing data have been included in the analysis, for a better spatial coverage. The local significance of trends has been analysed with the nonparametric Mann-Kendall (MK) test for the annual and seasonal mean wind speed. The MK test is a rank-based procedure, especially suitable for non-normally distributed data, data containing outliers and non-linear trends.The MK trend test applied to annual data series revealed substantial changes , with 93% of the stations presenting decreasing trends in mean wind annual speed at 10% significance level (2-tailed test). All significant trends are downward. The intra-Carpathic region is less affected than the rest of the country. On seasonal basis, the spatial patterns present some differences. In autumn and winter, the downward trend can be noticed in all extra-Carpathic regions, while in spring the decreasing trends are spread all over the country. In summer, the Transylvanian Depression and the Oriental Carpathians have no significant trends in wind speed, while other hilly and hollow areas do. Overall, the trend results indicate a consistent country-wide decrease in the average wind speed, more pronounced in the extra-Carpathic regions, and in the Meridional and Curvature Carpathians, and statistically significant in all seasons.