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Log10 E(k)*k**(5/3)<br />

6<br />

4<br />

2<br />

0<br />

5/3 corrected spectra<br />

for Hayange data<br />

Log10 E(k)*k**(5/3)<br />

17 <strong>Wind</strong> Extremes and Scales 101<br />

5<br />

4<br />

3<br />

2<br />

1<br />

5/3 corrected spectra<br />

for St. Médard d’Aunis data<br />

−2<br />

−3 −2 −1 0<br />

0<br />

−3 −2 −1 0<br />

Log10 k Log10 k<br />

(a) (b)<br />

Fig. 17.2. Compensated spectra of the two horizontal components of the data of<br />

Fig. 17.1a and of Fig. 17.1b, respectively. The horizontal plateau correspond to the<br />

Kolmogorov scaling<br />

Log10 Pr (⏐dV⏐>A)<br />

0<br />

−1<br />

−2<br />

−3<br />

−1<br />

Probability distributions for modulus<br />

of horizontal components of the wind<br />

Straight lines have slope of −7<br />

0<br />

Log10 A<br />

1<br />

2<br />

Log10 Pr (⏐dV⏐>A)<br />

0<br />

−1<br />

−2<br />

−3<br />

0<br />

Probability distributions for modulus<br />

of horizontal components of the wind<br />

Straight line have slopes of −7<br />

1<br />

Log10 A<br />

Fig. 17.3. Probability tails of the wind increments of the two horizontal components<br />

of the data of Fig. 17.1a and of Fig. 17.1b, respectively<br />

that the wind maxima distribution is a Frechet law [21], often called Generalized<br />

Extreme Value distribution of type 2 (GEV2), instead of the more<br />

classical Gumbel law (GEV1). GEV1 and GEV2 are quite distinct, since<br />

GEV1 has the same power law exponent qD as the original series, whereas<br />

GEV2 has a very thin tail corresponding to a double (negative) exponential.<br />

This sharp contrast results from the fact that a Frechet variable corresponds<br />

to the exponential of a Gumbel variable, therefore its distribution is often<br />

called “Log-Gumbel.” We will illustrate this with the help of Météo-France<br />

wind data, in particular those collected during the two “inland hurricanes”<br />

2<br />

3

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