Impact Of A Nocturnal Low-Level Jet On Surface-Layer Turbulent Characteristics

The impact of the Great Plains Low-Level Jet (GPLLJ) on the surface-layer turbulent characteristics is investigated using a long-term data set of eddy-covariance observations. The presence of the GPLLJ alters the distribution of the normalized wind velocity standard deviations and the turbulent intensity. Spectral analysis indicates that the presence of the GPLLJ can alter the low-frequency contribution in the u-spectra as well as the anisotropy of the u and w components of the flow. The intensity of the LLJ impacts the high-frequency contributions to the w-spectra. Using quadrant analysis to examine how the LLJ impacts sweeps and ejections, we find that the presence and the intensity of the LLJ alters the correlation between u and w. In addition, the intensity of the LLJ impacts the relative contribution from different quadrants to the overall flux and also impacts the third-order moments. Therefore, the presence of the LLJ alters surface-layer turbulence, while LLJ intensity appears to impact only a subset of these factors.