Sensitivity of WRF model to landuse, with applications to Chicago metropolitan Urban Heat Island and lake breeze

Abstract:

This study explores the sensitivity of high-resolution mesoscale simulations of urban heat island (UHI) in the Chicago metropolitan area (CMA) and its environs to landuse and urban physical parameterizations, with special emphasis on the role of lake breeze. A series of climate downscaling experiments are conducted using the Weather Research and Forecasting (WRF) model at 1 km horizontal resolution for a hot period with strong lake breeze. The study examines the impacts of land use data assimilation for initialization of the regional climate model, the role of urbanization on UHI and the lake breeze, and the effects of sub-grid scale land cover variability on urban predictions. Comparisons of simulations with station observations and MODIS satellite data show that the WRF model, with modifications, is able to replicate the measured surface temperature and wind speeds reasonably well. Variation of near surface temperatures was significant during nighttime, when the UHI was pronounced, and the inclusion of sub-grid scale variability of landuse in sub-urban areas improved the near surface temperatures predictions. The results show that representing surface characteristics with better detail and model initialization with reliable land surface observational data yield more accurate near surface temperatures and wind speeds.