In a recent investigation, data processing of average speed and maximum gusts of wind, using spectral analysis techniques, has been successfully applied for the first time to predict wind patterns.
The study was carried out in Spain by specialists from the Center for Research on Desertification (CIDE), a joint center of the Higher Council for Scientific Research (CSIC), the University of Valencia (UV) and the Generalitat Valenciana, together with the Climate Change Center of Rovira i Virgili University (URV) in Tarragona
With their pioneering analysis, these researchers have managed to observe patterns with which to improve the seasonal prediction of wind in the Iberian Peninsula, which could have socioeconomic and environmental implications for the production of wind energy, among other uses.
Among the conclusions of the work, it has been observed that when the polar vortex (a large area of low pressure and cold air that surrounds the poles of the Earth) is weakened, as occurs with a situation of Sudden Stratospheric Warming (event in which the temperature of the polar stratosphere rises tens of degrees), the winds blow stronger two to three months later. On the other hand, it has also been possible to determine that there is no correlation between the average surface wind speed and the maximum gusts in periods of more than nine years, a situation that worsens in summer and decreases in winter.
To carry out the research, two techniques have been applied: multitaper, with which the spectral density is estimated to detect any periodicity in the data, and wavelet, with which these periodicities can be located in time. The analysis from the spectra has made it possible to identify behavior patterns that help researchers to determine if it is possible to find sources of predictability in the wind speed or if, on the contrary, its behavior is chaotic. Likewise, they have also been able to determine time-lag correlations that occur with a certain periodicity between wind speed and other climatic variables of interest.
Wind-blown vegetation in coastal terrain. (Photo: Albert E. Theberge/NOAA Corps)
As Eduardo Utrabo, a CSIC researcher at CIDE, states, “analyses in the frequency domain, such as those applied in this study, are ideal for studying the weather patterns of phenomena such as El Niño-Southern Oscillation.”
In the climate system there are oscillations that are repeated with specific periods of time throughout the years. One of the best known examples is the El Niño-Southern Oscillation, which affects a large part of the global climate and which consists, among other elements, in the variation of the surface temperature of the water of the eastern equatorial Pacific every certain number of years. El Niño and La Niña correspond, respectively, with the warm phase and the cold phase of this pattern. Each phase carries a characteristic signal in the winds and in the tropical precipitations that in turn have global repercussions. The study of these patterns is of great importance since they are one of the main sources of predictability on a seasonal scale.
“The data obtained is highly applicable to the sector, such as the production of wind energy or the dispersion of polluting agents and greenhouse gases,” says Manola Brunet, director of the URV’s Center for Climate Change and one of the authors of the study.
The study is entitled “A spectral analysis of near-surface mean wind speed and gusts over the Iberian Peninsula”. And it has been published in the academic journal Geophysical Research Letters. (Source: Isidoro García Cano / CSIC)