An Assessment of HRRR Boundary Layer Performance within the Salt Lake Valley, Utah

In support of efforts underway in the Salt Lake Valley to better understand hyper-local sources of air pollution, a review and assessment of the variability in local meteorological factors related to the atmospheric boundary layer is being conducted. Gridded meteorological fields from the operational High Resolution Rapid Refresh (HRRR), available at hourly temporal and 3-km spatial resolution, are assessed against available surface mesonet observations, as well as vertical measurements of boundary layer structure and winds from remote sensors, atmospheric soundings, and other opportunistic datasets.

Case studies of interest to the air pollution research community were selected for further analysis and presented here. Gridded HRRR surface fields, used as an initial background, were expanded temporally and spatially and analyzed for deviations through integration with surface observations via the University of Utah Two-Dimensional Variational Analysis (UU2DVAR) technique. Boundary layer height estimates, as well as boundary layer winds, were assessed against available twice-daily atmospheric soundings from the Salt Lake City NWS office, as well as other local remote and in-situ opportunistic sensors (e.g. sodars, ceilometers, temperature profiles courtesy of an instrumented news helicopter) when available and applicable. Results are then discussed with respect to localized flow patterns often present in the Salt Lake Valley due to both local terrain and the presence of the Great Salt Lake.