## 4 Results and Discussion
### High Level Wind Speed Extrapolation and Validation
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Area**} & \multirow{2}{*}{**Method**} & \multicolumn{6}{c}{**Wind Shear Exponent under Different Stability Conditions**} \\ \cline{3-8}  & & **A** & **B** & **C** & **D** & **E** & **F** \\ \hline \multirow{4}{*}{SJB} & PL & \multicolumn{6}{c}{0.0679} \\  & WSE-RG & 0.1861 & 0.0558 & 0.0676 & 0.3825 & 0.0809 & 0.0981 \\  & WSE-MO & 0.2875 & 0.0474 & 0.0789 & 0.2753 & 0.1156 & 0.0963 \\  & WSE-WDSD & 0.0648 & 0.0774 & 0.0931 & 0.0608 & 0.0779 & 0.0523 \\  & WSE-WSR & 0.0863 & - & 0.0637 & 0.1309 & 0.4704 & - \\ \hline \multirow{4}{*}{GFC} & PL & \multicolumn{6}{c}{\(-\)0.0023} \\  & WSE-WDSD & 0.0066 & 0.0224 & 0.0307 & 0.0030 & 0.0239 & -0.0175 \\  & WSE-WSR & \(-\)0.1111 & 0.0081 & 0.0147 & 0.1500 & 0.9619 & - \\ \hline \multirow{4}{*}{HNH} & PL & \multicolumn{6}{c}{0.1790} \\  & WSE-WDSD & 0.1466 & 0.1455 & 0.1373 & 0.1740 & 0.2587 & 0.3703 \\  & WSE-WSR & \(-\)0.0079 & - & - & 0.1227 & 0.3278 & 0.4807 \\ \hline \multirow{4}{*}{**Area**} & \multirow{2}{*}{**Method**} & \multicolumn{6}{c}{**Wind Shear Exponent under Different Stability Conditions**} \\ \cline{3-8}  & & **A** & **B** & **C** & **D** & **E** & **F** \\ \hline \multirow{4}{*}{SJB} & PL & \multicolumn{6}{c}{0.0679} \\  & WSE-RG & 0.1861 & 0.0558 & 0.0676 & 0.3825 & 0.0809 & 0.0981 \\  & WSE-MO & 0.2875 & 0.0474 & 0.0789 & 0.2753 & 0.1156 & 0.0963 \\  & WSE-WDSD & 0.0648 & 0.0774 & 0.0931 & 0.0608 & 0.0779 & 0.0523 \\  & WSE-WSR & 0.0863 & - & 0.0637 & 0.1309 & 0.4704 & - \\ \hline \multirow{4}{*}{GFC} & PL & \multicolumn{6}{c}{\(-\)0.0023} \\  & WSE-WDSD & 0.0066 & 0.0224 & 0.0307 & 0.0030 & 0.0239 & -0.0175 \\  & WSE-WSR & \(-\)0.1111 & 0.0081 & 0.0147 & 0.1500 & 0.9619 & - \\ \hline \multirow{4}{*}{HNH} & PL & \multicolumn{6}{c}{0.1790} \\  & WSE-WDSD & 0.1466 & 0.1455 & 0.1373 & 0.1740 & 0.2587 & 0.3703 \\ \cline{1-1}  & WSE-WSR & \(-\)0.0079 & - & - & 0.1227 & 0.3278 & 0.4807 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Wind shear exponents in different areas. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Area**} & \multirow{2}{*}{**Methods**} & \multirow{2}{*}{**MRE**} & \multirow{2}{*}{**RMSE (m/s)**} & \multicolumn{2}{c}{**Calculated Mean Speed**} & \multicolumn{1}{c}{**Measured Mean Speed**} \\  & & & & **(m/s)** & **(m/s)** \\ \hline \multirow{4}{*}{SJB} & PL & \(-\)1.58\% & 0.378 & 6.6909 & \\  & WSE-WDSD & \(-\)1.58\% & 0.3781 & 6.6911 & \\  & WSE-MO & 0.22\% & 0.3337 & 6.8229 & 6.8210 \\  & WSE-RG & 0.63\% & 0.3231 & 6.8081 & \\  & WSE-WSR & \(-\)1.52\% & 0.3311 & 6.7242 & \\ \hline \multirow{4}{*}{GFC} & PL & \(-\)0.33\% & 0.543 & 6.2069 & \\  & WSE-WDSD & \(-\)0.02\% & 0.5276 & 6.2386 & 6.2904 \\  & WSE-WSR & \(-\)0.03\% & 0.536 & 6.2346 & \\ \hline \multirow{4}{*}{HNH} & PL & \(-\)7.38\% & 0.8732 & 7.2567 & \\  & WSE-WDSD & \(-\)3.17\% & 0.7931 & 7.2681 & 7.5972 \\ \cline{1-1}  & WSE-WSR & \(-\)3.26\% & 0.7035 & 7.2815 & \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Mean wind speed relative error (MRE), root-mean-square error (RMSE) of wind speed and mean speed at the hub height in the three cases. atmospheric stability condition is E. Through the comparison of RMSEs, it is seen that the WSE-WDSD method performs well in almost all the conditions. For HNH, the absolute values of MREs of the WSE-WDSD and WSE-WSR methods are smaller than those obtained by the PL method. The accuracy of both the WSE-WDSD and WSE-WSR methods has been greatly improved. It is shown that these two atmospheric stability classification methods are suitable for flat terrain. And the WSE-WSR method is more effective than the WSE-WDSD method especially in unstable conditions. The monthly and daily variations of RMSE of the three cases using different wind speed extrapolation methods are shown in Figure 6. For SJB, the results of WSE-WDSD are very close to the traditional PL method, indicating that the WSE-WDSD method is inaccurate in the complex terrain plateau.