Improving Air Quality Modeling for the Wasatch Front/Cache Valley Winter Air Pollution Episodes Erik Crosman 1, John Horel 1, Lance Avey 2, Chris Foster 1, Erik Neemann 1, Brian Blaylock 1, 1 University of Utah Department of Atmospheric Sciences 2 Utah Division of Air Quality

Study Objectives Determine appropriate WRF atmospheric model configurations including treatment of the underlying surface to improve simulations of wintertime cold pool events along the Wasatch Front and in the Cache Valley that lead to high PM2.5 pollution Collaborate with Utah DAQ staff to identify and simulate selected cold-air pool episodes to be used in PM2.5 SIP development PCAPS 10P5 & 1

Getting the meteorology models right: We need to parameterize all of these processes right! Clouds Snow Cover and Land Use Mixing Depth of Cold layer Transport Warm air Cold air H High pressure

Timeline Fall Complete identification of possible prior winter case studies with DAQ staff; Graduate student attends CMAQ workshop to become familiar with atmospheric modeling needs required for CMAQ during late October. Winter Testing of WRF sensitivity to land surface schemes (USGS, NLCD, MODIS) and snow cover options. Spring Complete testing of WRF sensitivity to PBL and cloud microphysics parameterization schemes Spring Assess whether any air pollution events should be examined. Summer Testing of large-eddy simulations October 15. Complete summary of recommended appropriate WRF model cold pool setup

Research Update 11 March 2015 Current work in these 3 areas 1. Determining the importance of snow albedo and depth corrections to CAP in Salt Lake/Utah Valley (this has been done for Uintah Basin in Neemann et al. 2015) 2. Selecting appropriate land use definition, soils, urban extent, and vegetation depth 3. Better understanding cause of CAP initialization response

Albedo Changes in Uintah Basin 6 OriginalModified is average albedo measured at Horsepool during 2013 Uintah Basin Winter Ozone Study

Initial Results—WRF Albedo Low in Salt Lake Valley PCAPS observations WRF

Improving WRF Snow Cover Parameterization -Idealized snow cover in Uintah Basin and mountains -Snow albedo changes -Edited VEGPARM.TBL Allows model to achieve high albedos measured in basin 8 Snow Depth

Land Use Sensitivity MODIS NLCD USGS USGS colder; next step why? Less vegetation?

Initialization 2 Initialization 1 31 December January January 2011 WRF CAP Sensitivity to Initialization Time Identical simulations started 1 day apart Obs 31 Dec 1 Jan WRF CAP Sensitivity to Initialization Time Identical simulations started 1 day apart 1 Jan

Next Steps Spring Recommendation on cold pool land use scheme/vegetation modifications Recommendation on snow cover treatment in SLV April 2015 Alison Nugent, NCAR visiting scientist, implement Thompson Aerosol-aware scheme May 2015 Western Air Quality Modeling Workshop Summer Targeted large-eddy simulation testing on mix-out case PBL and cloud microphysics parameterization schemes