2017 Utah Winter Fine Particulate Study Final Report Submitted to the Utah Division of Air Quality (UDAQ) March 16, 2018 Munkhbayar Baasandorj University of Utah Steven Brown NOAA ESRL Sebastian Hoch University of Utah Erik Crosman University of Utah Russell Long EPA ORD Phillip Silva USDA Logan Mitchell University of Utah Ian Hammond Utah State University Randal Martin Utah State University Ryan Bares University of Utah John Lin University of Utah John Sohl Weber State University Jeff Page Weber State University i Stuart McKeen NOAA ESRL Christopher Pennell UDAQ Alessandro Franchin NOAA ESRL Ann Middlebrook NOAA ESRL Ross Petersen University of Utah Gannet Hallar University of Utah Dorothy Fibiger NOAA ESRL Caroline Womack NOAA ESRL Erin McDuffie NOAA ESRL Alexander Moravek University of Toronto Jennifer Murphy University of Toronto Amy Hrdina University of Toronto Joel Thornton University of Washington Lexie Goldberger University of Washington Ben Lee University of Washington Theran Riedel EPA ORD Andrew Whitehill EPA ORD Kerry Kelly University of Utah Jaron Hansen BYU Delbert Eatough BYU ii Table of Contents 1 INTRODUCTION 1 1.1 CHEMICAL CHARACTERISTICS OF PM2.5 3 1.2 METEOROLOGY OF PCAPS AND EXCHANGE PROCESSES 5 1.3 OVERVIEW OF 2016-17 WINTER 6 1.4 SCIENTIFIC QUESTIONS AND STUDY GOALS 13 2 METHODS 15 2.1 TWIN OTTER MEASUREMENTS 15 2.1.1 INSTRUMENT PAYLOAD 15 2.1.2 TWIN OTTER FLIGHT STRATEGY 19 2.2 BALLOON OBSERVATIONS 21 2.3 NEWS HELICOPTER OBSERVATIONS 23 2.4 GROUND SITE NETWORK 24 2.4.1 CACHE VALLEY SITES 25 2.4.2 SALT LAKE VALLEY SITES 31 2.4.3 METEOROLOGICAL OBSERVATIONS IN THE SLV 34 2.4.4 TRAX OBSERVATIONS 40 2.4.5 UTAH VALLEY SITE 41 2.4.6 PASSIVE AMMONIA NETWORK 42 2.5 MODEL SUPPORT AND APPLICATIONS 45 3 OBSERVATIONS OF AEROSOLS AND TRACE GASES 47 3.1 AEROSOL COMPOSITION AND SIZE DISTRIBUTIONS 47 3.1.1 COMPARISON AMONG THE MAJOR BASINS 47 3.1.2 VERTICAL AEROSOL DISTRIBUTIONS 58 3.1.3 SUMMARY AND CONCLUSIONS 63 3.2 OXIDIZED NITROGEN AND OZONE 64 3.3 AMMONIA 77 3.3.1 PASSIVE NH3 SAMPLER NETWORK MEASUREMENTS 77 3.3.2 GROUND BASED REAL TIME NH3 MEASUREMENTS 81 3.3.3 AIRCRAFT NH3 MEASUREMENTS 85 3.4 HALOGENS 91 3.5 GREENHOUSE GASES 102 3.6 VOLATILE ORGANIC COMPOUNDS 104 4 LIMITING AND EXCESS REAGENTS FOR AMMONIUM NITRATE 110 4.1 METHOD #1 - MOLAR RATIOS OF OXIDIZED TO REDUCED NITROGEN 110 iii 4.1.1 TWIN OTTER OBSERVATIONS 111 4.1.2 GROUND SITE OBSERVATIONS 114 4.2 METHOD #2 - THERMODYNAMIC MODELING 116 4.2.1 RESULTS FROM ALL REGIONS (ALL TWIN OTTER DATA) 117 4.2.2 SALT LAKE VALLEY 120 4.2.3 CACHE VALLEY 122 4.2.4 UTAH VALLEY 124 4.3 SUMMARY, FUTURE ANALYSES AND OUTSTANDING QUESTIONS 126 5 EXCHANGE PROCESSES 128 5.1 DOWN-CANYON FLOWS 129 5.2 DAYTIME SIDEWALL VENTILATION - 29 JANUARY 2017 131 5.3 LAKE BREEZE CIRCULATION - 30 JANUARY 2017 132 5.4 SYNOPTICALLY-FORCED LAKE EXCHANGE 133 5.5 INTER-BASIN EXCHANGE 134 6 EMISSIONS 137 6.1 AMMONIA EMISSIONS 137 6.2 RESIDENTIAL WOOD COMBUSTION 140 7 MODELS OF NORTHERN UTAH WINTER AIR QUALITY 142 7.1 UTAH REGULATORY MODELING PROGRESS 143 7.1.1 EFFECT OF AMMONIA INJECTION ON MODEL PERFORMANCE 144 7.1.2 EFFECT OF METEOROLOGICAL MODELING ON MODEL PERFORMANCE 145 7.2 WRF/CHEM MODELING FOR UWFPS-2017 147 7.2.1 WRF/CHEM CONFIGURATION 148 7.2.2 EMISSIONS 150 7.2.3 UNCERTAINTIES RELATED TO METEOROLOGY 150 7.2.4 UNCERTAINTIES RELATED TO EMISSIONS AND PHOTOCHEMISTRY 152 7.2.5 COMPARING WITH COLUMN INTEGRATED DATA FROM TWIN OTTER MISSED APPROACHES 155 7.3 UNIVERSITY OF UTAH TRAJECTORY INFORMATION 156 8 IMPLICATIONS CONTROL STRATEGY DEVELOPMENT 158 8.1 LIMITING REAGENT IN AMMONIUM NITRATE FORMATION 158 8.2 EMISSIONS OF NH3 AND NOX 159 8.3 RESIDENTIAL WOOD COMBUSTION 161 9 RECOMMENDATIONS FOR FURTHER RESEARCH 163 10 REFERENCES 169 iv List of Figures Figure 1.1 Map of Utah (left) with area of detail (right) showing the three major valleys subject to wintertime particulate matter pollution. The Cache Valley in the north spans northern Utah and southern Idaho and is primarily rural, while the Salt Lake and Utah Valleys to the south include the major urban areas of Salt Lake City and Provo.................................................. 1 Figure 1.2 Map of the three federal Daily PM2.5 nonattainment areas in Utah. The Salt Lake (blue) and Utah (green) nonattainment areas have recently been designated as “serious”. ........... 2 Figure 1.3 Potential temperature at the base and top of the Salt Lake City Basin from radiosonde observations by the National Weather Service (top), and the Valley Heat Deficit (VHD, black) and the smoothed observations of PM2.5 pollutant concentrations (red) from the UDAQ Hawthorne (HW) site. Data covers the main observational period of the experiment, from 15 December 2016 through 20 February 2017. Note that the horizontal dashed line marks the NAAQS for PM2.5 and the horizontal red-black dashed line marks the VHD threshold value of -3 -3 4.04 MJ m and a PM2.5 concentration of 17.5 μg m . ........................................................ 7 Figure 1.4 Daily average PM2.5 mass loadings for representative sites in each of the three valleys indicated in Figure 1.1 during the 2016 - 2017 winter (December 1 2016 - February 28, 2017). Grey shaded regions indicate the times during which the Twin Otter research flights occurred. Bars across the top indicate the pollution episodes in Table 1.1 .......................................... 8 Figure 1.5 Time-height cross sections of ceilometer backscatter profile and contours of isentropes at the Landfill Site (LFL) in the Salt Lake Basin for three of the pollution episodes in early 2017. Isentropes are from KSLC radiosonde dataset. Note that some intermittent power outages occurred at the site. ............................................................................................. 10 Figure 1.6 Time series of PM2.5, PM10, NOx, O3, RH and T for representative sites in each of the three valleys during the UWFPS (January 15 - February 15, 2017). ................................. 12 Figure 2.1 Instrument layout inside the Twin Otter showing the location of the scientific instruments and the location of the seats for the flight scientist and a second scientist (jump seat). ................................................................................................................................. 18 Figure 2.2 Left: Photograph of the scientific instrument payload inside of the aircraft (photograph taken from the rear of the aircraft, facing forward). Right: Indication of the locations of sample inlets. The AMS + UHSAS shared a custom aerosol inlet on the right side of the aircraft, - while the I ToF CIMS sampled from a custom gas phase inlet on the left side. Both NOxCaRD and the QC-TDLAS instruments sampled through upward facing inlets mounted on the top of the aircraft. .................................................................................................................... 18 Figure 2.3 Example Twin Otter flight patterns. Flight tracks are from January 18, 2017, and are color coded by altitude above sea level as the legend shows. Blue circles indicate locations of airfields throughout the region where the Twin Otter executed missed approaches. The v left panel shows the north flight plan that covered the north metro areas along the east side of the Great Salt Lake, the Cache and Bear River Valleys, Great Salt Lake and the Tooele Valley. The right panel shows the south flight plan that covered the southern end of Great Salt Lake, and the Salt Lake and Utah Valleys. Bottom panels show aircraft altitude (left axes = km, right axes = feet) against elapsed flight time, with locations of missed approaches corresponding to the airfields in the upper panels. ............................................................. 20 Figure 2.4 The tethered balloon platform carried an ozonesonde on every flight with other payloads alternating between flights. The launch point was collocated with the Utah Division of Air Quality Ogden O2 ground station to provide a calibration reference. The winch raised and lowered the balloon from ground to 500 feet (150 m) high, then back down. Each flight lasted approximately 6 minutes. ........................................................................................ 23 Figure 2.5 The KSL-TV helicopter with inlet location shown (top, A) and instrument box (bottom, B). ..................................................................................................................................... 24 Figure 2.6 Map showing the locations of the ground-based observation sites and the tethered- balloon deployment. .......................................................................................................... 25 Figure 2.7 Map (UTM grid, 100 m elevation contours) of the northern part of the Salt Lake Valley showing the locations of meteorological observation sites. Blue dots mark sites with multiple meteorological sensors and/or profilers, as described in Table 2.7. Red dots mark automatic temperature data loggers deployed along an elevation transect between ~1300 m and 2150 m ASL. The thick elevation contour approximately shows the coastline of the Great Salt Lake. .......................................................................................................................................... 35 Figure 2.8 The TRAX Red, Green, and Blue train lines in the SLV. The University of Utah greenhouse gas monitoring network (blue triangles), University of Utah air quality research sites (yellow squares), and the UDAQ’s HW site (cyan star) are also shown. The population