were not resolvable with the data used, since the minimum wind speed in the profile occurred at the output level, which was not used in the LS parameter calculation. Figure 14 shows the average profiles obtained at the four four-level towers (i.e., 20, 21, 3131, and 3132) and the single profile with the worst LS methodology performance for each tower. In conclusion, the KSC data from the four-level towers confirmed that the LS methodology produces both accurate and conservative results, and that three levels are adequate to extrapolate the full vertical profile of wind speed.
3.2.2. Part 2: Surface Stations
 Ideally, the LS methodology should be applied to simultaneous sounding and surface data. In other words, for each given hour, the LS parameters should be determined from the soundings and then applied, at the surface station, to the value of VR valid at the same hour as the sounding profiles. The daily average of V80 at a surface station (i.e., V80) should thus be calculated as follows:
where Lk is the LS function at sounding station k at hour h, VRh is 10-m wind speed at the surface station of interest at hour h, and K is the number of surrounding soundings (K = 5 in this study).
 However, neither sounding nor surface data are available on an hourly basis for all locations. Daily averages of 10-m wind speeds at the surface stations (i.e., VR) and twice-a-day sounding profiles (at 0000 and 1200 UTC) were usually the only available data worldwide. As such, Figures 4-10 were derived by using the following equation:
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