The sensitivity of sea and lake breezes to variations in surface and atmospheric state in large-eddy simulations

Sea and lake breezes have significant societal impacts, including modulating the formation, transport, and destruction of pollutants near metropolitan coastal areas. Sea and lake breezes also interact in a variety of ways with complex terrain, including flow channeling, blocking, and coupling of the sea or lake breezes with upslope flows. While the body of theoretical, observational, and numerical studies related to lake and sea breeze systems and associated air quality issues is extensive, most numerical modeling of lake and sea breezes have been conducted using two-dimensional hydrostatic models run at coarse horizontal resolution (1-4 km). These studies are unable to resolve both the vertical motion near the sea breeze front and the three-dimensional turbulence field. In this study, the Weather Research and Forecasting (WRF) model is used as a fully three-dimensional, nonhydrostatic model at large-eddy simulation (LES) resolution (~100 m) where most boundary-layer turbulence is explicitly resolved. Several dozen idealized LES simulations with various surface and atmospheric state have been conducted to determine the impact of variations in terrain slope and height, lake dimension, background geostrophic wind, atmospheric stability, and surface heat flux on the depth, intensity, and inland penetration distance of lake and sea breezes. The results of these LES simulations will be presented. We will also compare the numerical results to observations of lake breezes obtained from Utah's Great Salt Lake. An observational field study of Great Salt Lake breezes was conducted by undergraduate students at the University of Utah in the summer of 2009 and included an array of surface weather stations, radiosonde profiles, and high resolution surface temperature data from the Moderate Resolution Imaging Spectroradiometer.