Observations of Spatial and Temporal Variability of the Great Plains Low Level Jet

Abstract:

The Southern Great Plains of the United States frequently experience a nighttime southerly low level jet (LLJ). The LLJ has been shown to significantly contribute to the regional aerosol and moisture budget, and affect the convective precipitation. In this study, we leverage the data collected by four Radar Wind Profilers (RWP) part of the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) to characterize the great plains LLJ. Three RWPs are located roughly at the vertices of an equilateral triangle with length of 25 km, while the fourth is roughly located at the centroid of the triangle. The raw Doppler spectra from these RWPs were reprocessed to calculate the moments and the boundary layer winds at 10 minute temporal and 50 m range resolution. Data from May to September collected from 2015 to 2019 are used in this study. A threshold of 12 m/s wind speed was used to determine the presence, location, and the strength of the jet. Our initial results point towards substantial changes in the strength, location and timing of the jet in the North-South and East-West directions even at these short distances. Our future work will focus on quantifying these changes over the years and understand their correlation with observed moisture and precipitation properties.