Session Presentations

Patrick M. Manseau^1*, Radenko Pavlovic², Si Jun Peng¹, Jacinthe Racine¹, Michael Moran³, and Jack Chen³

¹Canadian Meteorological Centre Operations Division, Environment and Climate Change Canada (ECCC), Montreal, Quebec, Canada

²National Predictions Development Division, ECCC, Montreal, Quebec, Canada

³Air Quality Research Division, ECCC, Toronto, Ontario, Canada

Concern about the health and socioeconomic impacts of wildfires and fire smoke is growing around the world, especially as wildfire frequency and severity are expected to increase under climate change. Vegetation fire danger warning and smoke forecast systems are a key component to increase societal resilience to wildfires and to raise awareness of the impact of fire smoke on air quality and population health. The World Meteorological Organization (WMO) is spearheading better international collaboration on this topic, including through the creation of several Regional Vegetation Fire and Smoke Pollution Warning and Advisory Centres (RVFSP-WACs). These centres will enhance the ability of countries to deliver timely and quality vegetation fire and smoke pollution forecasts, observations, information and knowledge to users through an international partnership of research and operational communities. The first RVFSP-WAC, which covers southeast Asia, was established in Singapore. Environment and Climate Change Canada (ECCC) is now working to create a North American RVFSP-WAC, the second to be established worldwide.

For this project, ECCC is leveraging existing products from multiple agencies, including wildfire danger and fire weather index maps, operational North American air quality forecasts, which include near-real-time (NRT) vegetation fire emissions and smoke plume forecasts, and sub-seasonal temperature and precipitation forecasts. To date, to supplement its own products ECCC has accessed feeds of multiple global and regional NRT smoke-related forecasts from various agencies such as ECMWF, NASA, NOAA, FMI and JMA to generate a multi-model ensemble smoke forecast over North America. Development of this Centre is continuing, but some demonstration products are already accessible from a central web portal. This presentation will describe the status of the North American RVFSP-WAC, show examples of preliminary forecast and analysis products, and outline future work.

Joseph L. Wilkins, Susan O’Neill, Ernesto Alvarado, Amber Soja, Hyundeok Choi, Emily Gargulinkski, Benjamin De Foy, George Pouliot, Thomas Pierce, Anne M. Thompson, David Peterson, Edward Hyer, Sim Larkin.

Air quality models are used to assess the impact of smoke from wildland fires, both prescribed and natural, on ambient air quality and human health. However, the accuracy of these models is limited by uncertainties in the parametrization of smoke plume injection height (PIH), vertical distribution, and emission factors used for criteria pollutants. These errors can propagate, resulting in under or overestimations over large areas in public health analysis. We compared PIH estimates from the plume rise method (Briggs) in the Community Multiscale Air Quality (CMAQ) modelling system with observations from the 2013 California Rim Fire and 2017 prescribed burns in Kansas to study long range transport of smoke impacts to St. Louis, Missouri. We also examined PIHs estimated using alternative plume rise algorithms, model grid resolutions, and temporal burn profiles. For the Rim Fire, the Briggs method performed as well or better than the alternatives evaluated (mean bias of less than 5–20% and root mean square error lower than 1000 m compared with the alternative plume methods). PIH estimates for the Kansas prescribed burns improved when the burn window was reduced from the standard default of 12 h to 3 h. This analysis suggests that meteorological inputs, temporal allocation, and heat release are the primary drivers for accurately modelling PIH. Further our results indicate that long range transported smoke can add an additional smoke burden on a city, leading to 10 – 80 ppbv of ozone enhancement at the surface and ~15-30 % enhancement of the total column.

Jingting Huang, Kaiyu Chen, and Heather A. Holmes

Department of Chemical Engineering, University of Utah, Salt Lake City, UT, 84112, USA; jingting.huang@utah.edu (J.H.); ky.chen@utah.edu (K.C.); h.holmes@utah.edu (H.A.H.)

Wildfire risks are accelerating at unprecedented rates in the western U.S. due to exceptional drought conditions. Short- and long-term human exposure to fine particles generated by wildfire smoke is projected to increase and will worsen population health outcomes. The issue of how plume emissions are vertically distributed through the atmosphere is a current knowledge gap for air quality modeling. The proper vertical emission profiles are necessary for accurate simulation of atmospheric transport and deposition.

Whether aerosols are contained in or lofted above the planetary boundary layer height (PBLH) significantly affects the vertical placement and downwind transport of wildfire emissions. However, most existing plume rise parameterizations, based on Briggs’ solutions (1969, 1975, 1984), are inappropriate for the physical characteristics of wildfire smoke plumes, especially for the large wildfires in the western U.S. In this study, we explore the plume injection height (PIH) for two large wildfire events [i.e., Rim Fire (2013) and Soberanes Fire (2016)] by evaluating notable and novel plume rise schemes with inputs from satellite remote sensing data, emission inventories, and numerical weather prediction. Simulated results from different plume rise algorithms are further compared to observations from field campaigns or aircraft measurements and satellite-derived PIH products. The final objective of this study is to develop a new plume rise model over the western U.S for use in 3-D chemical transport models.

Keywords: Air Quality; Wildfire Emissions; Smoke Plume Injection Height

Joshua Fu, Cheng-Pin Kuo, and Cheng-En Yang 

Department of Civil and Environmental Engineering, The University of Tennessee, Knoxville, TN, USA

Our CMAQ results have shown that the wildfire-induced air pollutant concentration changes could be as high as 102 ppb for O3 and 259 μg/m3 for PM2.5 at local scale in the western United States, under the Representative Concentration Pathway 8.5 (RCP8.5) climate scenario. Wildfires and climate change are increasingly causing a rise in air pollution and a human health impact. Future projections of wildfire emissions show a rise in pollutant concentrations between 2050 - 2059. Air pollutants have many important effects, such as influencing Earth’s radiative balance, diminishing human quality of life and exacerbating human health conditions, injuring ecosystems, damaging buildings and monuments, interfering with food safety, accelerating animal extinctions, altering Earth’s atmospheric composition, and impacting deposition rates. O3 and PM2.5 concentrations are damaging to human health and property, and there are long-term effects on climate change. In addition to O3 and PM2.5, air toxics such as formaldehyde (CH2O), methane (CH₄), carbon monoxide (CO), and nitrogen dioxide (NO₂) also impose threats to environmental and human health and are not paid too much attention. Since CH2O, CH₄, CO, and NO₂ are projected to increase in the future over CONUS, it is essential to examine how wildfires would influence their concentrations. In this presentation, we will present the trends and correlations between wildfires and the concentrations of CH₄, CO, CH2O, and NO₂. Uncertainty of the projected pollutant concentrations will also be presented.

ShihMing Huang, Samantha Kramer, Melissa Chaveste, Crystal McClure, Fred Lurmann

California has experienced increased catastrophic wildfires over the last decade, prompting the need for increased prescribed fires. We developed two prescribed fire emissions scenarios and assessed the public’s exposure to fire smoke. In the baseline scenario, we established a 10-year (2008-2017) wildfire and prescribed fire inventory for California by merging satellite hotspots and agency records. The fire inventory and meteorological data were used to initialize daily PM_2.5 smoke modeling in BlueSky Smoke Modeling Framework with HYSPLIT dispersion option. Dispersion modeling was completed independently for wildfires and prescribed fires. The modeled PM_2.5 results were used to assign daily exposure for each California ZIP code. In the target prescribed fire scenario, we modeled PM_2.5 exposures from multiple annual cycles of hypothetical prescribed fires. The representative distribution of prescribed fires by size and vegetation type was developed based on the baseline inventory and applied to the target acreage goals. Fire locations were randomly distributed within high-fire-risk areas. Fire dates were randomly assigned based on historical burn days for each air basin. The hypothetical fires were then used to initialize smoke modeling using the same representative climatology for each annual cycle. We will present the baseline fire history and modeled smoke exposures from each scenario.

Matthew J. Alvarado¹, Marikate Mountain¹, and Archana Dayalu¹

¹Atmospheric and Environmental Research, Lexington, MA

Plume-scale process models allow for explicit simulation and examination of the chemical and physical transformations of trace gases and aerosols within biomass burning smoke plumes, and they may be used to develop parameterizations of this aging process for coarser grid-scale models. One challenge for plume-scale models is to account for the horizontal and vertical gradients in smoke chemistry caused by differences in concentrations and photolysis rates within the plume. Here we present an update to the 2D Lagrangian plume-scale process model SAM-ASP to incorporate on-line photolysis calculations using the fast version of the Tropospheric Ultraviolet and Visible (TUV) aerosol model. The photolysis calculations are fully coupled to the aerosol concentrations within SAM-ASP to account for the impact of the changing aerosol properties on photolysis rates, and thus ozone and secondary organic aerosol chemistry, within the plume. We describe the coupled model and show some initial simulations of the impact of the more realistic photolysis on the plume chemistry.