Meteorological modeling sensitivity to parameterizations and satellite-derived surface datasets during the 2017 Lake Michigan Ozone Study

Abstract

Abstract. High-resolution simulations were performed to assess the impact of different parameterization schemes, surface initialization datasets, and analysis nudging on lower-tropospheric conditions near Lake Michigan. Simulations were run where climatological or coarse-resolution surface initialization datasets were replaced by high-resolution, real-time datasets depicting lake surface temperatures (SST), green vegetation fraction (GVF), and soil moisture and temperature (SOIL). Comparison of a baseline simulation employing a configuration similar to that used at the Environmental Protection Agency (“EPA”) to another simulation employing an alternative set of parameterization schemes (referred to as “YNT”) showed that the EPA configuration produced more accurate analyses on the outermost 12-km resolution domain, but that the YNT configuration was superior for higher-resolution nests. The diurnal evolution of the surface energy fluxes was similar in both simulations on the 12-km grid but differed greatly on the 1.3-km grid where the EPA simulation had much smaller sensible heat flux during the daytime and physically unrealistic ground heat flux. Switching to the YNT configuration led to substantial decreases in root mean square error for 2-m temperature and 2-m water vapor mixing ratio on the 1.3-km grid. Additional improvements occurred when the high-resolution satellite-derived surface datasets were incorporated into the modeling platform, with the SOIL dataset having the largest positive impact on temperature and water vapor. The GVF and SST datasets also produced more accurate temperature and water vapor analyses, but degradations in wind speed, especially when using the GVF dataset. The most accurate simulations were obtained when using the high-resolution SST and SOIL datasets and analysis nudging above 2 km AGL.

High-resolution air quality simulations of ozone exceedance events during the Lake Michigan Ozone Study

“…This optimized configuration is hereafter referred to as the YNT_SSNG. Otkin et al (2023) found that the AP-XM configuration generally produced more accurate meteorological analyses on the 12 km domain, but its accuracy decreased with a finer model grid resolution. In contrast, the YNT_SSNG statistics showed consistent reductions in the root mean square error (RMSE) for 2 m temperature, 2 m water vapor mixing ratio, and 10 m wind speed relative to the AP-XM as the model resolution increased from 12 to 1.3 km.…”

“…In this work, we compare two CMAQ simulations, one with baseline meteorology and the other with meteorology from our optimized Weather Research and Forecasting (WRF) model configuration, as detailed in Part I (Otkin et al, 2023). Both sets of meteorological simulations employ a triple-nested domain configuration containing 12, 4, and 1.33333 (1.3) km resolution grids, respectively (Fig.…”

“…Both sets of meteorological simulations employ a triple-nested domain configuration containing 12, 4, and 1.33333 (1.3) km resolution grids, respectively (Fig. 1 in Otkin et al, 2023), constrained to 6 h, 0.25 • resolution Global Forecast System Final (GFS-FNL) analyses and using the rapid radiative transfer model for general circulation models (RRTMG) longwave and shortwave radiation (Iacono et al, 2008;Mlawer et al, 1997) on all three domains, along with the Kain-Fritsch cumulus scheme (Kain, 2004) on the outer two domains and an explicit convection on the innermost domain. Both simulations have the same vertical resolution throughout, with six model layers below 200 m, four model layers below 100 m, and the lowest three layers at ∼ 9, 27, and 55 m a.g.l.…”

“…The areas along the Lake Michigan shoreline are susceptible to high-ozone amounts because of a combination of abundant precursor emissions and transport processes, particularly the lake breeze circulation. The relationships between area emissions and meteorology as they impact air quality along the Lake Michigan shoreline have been characterized in field campaigns (Sexton and Westberg, 1980;Dye et al, 1995;Foley et al, 2011;Stanier et al, 2021), and the meteorological component is the subject of Part 1 of this study (Otkin et al, 2023). Ozone concentrations along coastlines can be enhanced significantly when urban emissions react within the shallow, stable marine boundary layer (Fast and Heilman, 2003).…”

“…We have developed a high-resolution, satellite-constrained meteorological modeling platform for the United States Midwest that supports the needs of the Lake Michigan Air Directors Consortium (LADCO), as they conduct detailed air quality modeling assessments for its member states. In Part I of this study, Otkin et al (2023) assessed the impact of different high-resolution surface datasets, parameterization schemes, and analysis nudging on near-surface meteorolog-ical conditions and energy fluxes relative to the model configuration and input datasets typically employed by the U.S. Environmental Protection Agency (EPA). In Part II of this study, we use the meteorological output obtained from two of these simulations as input to the EPA Community Multiscale Air Quality (CMAQ), model version 5.2.1 (Byun and Schere, 2006;Nolte et al, 2015), model simulations to assess the impact of these model changes on ozone forecasts in the Lake Michigan region.…”