39 Part 50 of IEC 61400 specifies methods and requirements for the application of instruments to 40 measure wind speed (and related parameters, e.g. wind direction and turbulence intensity). 41 Such measurements are required as an input to some of the evaluation and testing procedures 42 for wind energy and wind turbine technology (e.g. resource evaluation and turbine testing) 43 described by other standards in the IEC 61400 series. Part 50-2 is applicable specifically to 44 the use of ground mounted remote sensing wind measurement instruments, i.e devices which 45 measure the wind at some location generally above and distant from the location at which the 46 instrument is mounted (e.g. sodars, vertical profiling lidars). This document specifically 47 excludes other types of RSD such as forward facing or scanning lidars.