The Niwot Ridge has been the site of numerous chemical transport and spatial distribution studies, including the 2004 Carbon in the Mountains Experiment (CME); however, an in-depth characterization and understanding of the wind structure of this complex terrain does not exist. The CME will investigate the accuracy of carbon dioxide (CO₂) measurements in complex terrains (i.e. mountains, forests). Utilizing satellite data, Schimel determined that 25 to 50 % of total US carbon uptake, and up to 75% of total Western US uptake, occurs in mountainous terrain. Because turbulence is one of the transport processes and the boundary layer plays an integral role in transport and spatial distribution of chemicals, this study investigated the diurnal variation of the boundary layer structure in the Niwot Ridge utilizing a SODAR (sonic detection and ranging). Data from the SODAR was collected from March 15 to July 7, 2004 with measurements every 10 to 15 minutes. Plots of the wind profiles were generated and analyzed utilizing synoptic meteorological conditions at the site. The study found that the diurnal variation of wind speed and direction vary directly with the diurnal cycle of the boundary layer structure. Much of the dataset was found to have “bad” or missing data; in fact, some days had 50 to 70 % bad or missing data. This was partially attributed to the diurnal cycle of the boundary layer structure and nature of the investigated site. Further analysis of the diurnal variation of boundary layer structure in complex terrain is necessary.