Based on the 4-time daily wind speed data collected from 2001 to 2010 at the four sites (wind speeds within the range 3–20 m/s are used), the average yearly wind speed can be obtained (see Table 3). The Jonckheere–Terpstra test can judge whether several independent samples are from the same distribution, i.e., whether the average yearly wind speeds during the ten years have the same distribution or not. Using Eqs. (12) and (13), the p-values of average yearly value and yearly variance at the four sites can be found (see Table 3). For the average yearly value, the p-values at Site 1 and Site 3 are the same, and they are greater than the p-values at Site 2 and Site 4. If the significance level is 0.05, it EPZ-6438 is easy to find that all p-values are greater than 0.05. This result illustrates that the average yearly value at each site is from the same distribution, i.e., the average yearly value of the wind speed from 2001 to 2010 does not change significantly at the four sites. For the yearly variance, the p-values at Site 1, Site 3 and Site 4 are far greater than 0.05, but the p-value of Site 2 is a slightly less than 0.05, which indicates smog the distributions of the yearly variance at Site 1, Site 3 and Site 4 are the same, but at Site 2, the distribution is different. Above all, with regard to Site 1, Site 3 and Site 4, the average yearly wind speeds do not indicate large changes. Although the average yearly value is stable at Site 2, the instability of the variance indicates that the fluctuations in the yearly wind speed are large. Therefore, compared with Site 2, the wind energies at Site 1, Site 3 and Site 4 are more stable.