Analysis of the Smoke Plume over Northeast US caused by the Canadian Fires

Intensification of wildland fires across portions of Canada during June 2023 led to substantial smoke transport into the Eastern states of the USA that resulted in poor air quality across much of New England and the Mid-Atlantic regions. The time period spanning June 6^th through June 8^th coincided with enhanced smoke and reduced visibility across eastern CONUS as smoke was transported along the background synoptic patterns. A network of ceilometers and Doppler Lidars located across eastern states documented smoke advected into the region along with changes in the dynamical structure of the lower atmosphere. Realtime forecasts detailing the large-scale conditions and smoke properties from the High-Resolution Rapid Refresh (HRRR)-Smoke model were also available throughout this period, and are currently being used to evaluate against a network of remote sensing instruments.

As part of an ongoing investigation, we present preliminary results with a focus on data collected by the HALO Doppler scanning lidar located on top of the Herbert C. Hoover building in Washington DC. The HALO lidar was installed by the NOAA Chemical Sciences Laboratory (CSL) in support of the 2021-2024 Northeast Corridor Urban Test Bed study led by the National Institutes for Standards and Technology (NIST) in an effort to quantify greenhouse gas (GHG) fluxes over the Baltimore-Washington area. Measured products from the HALO lidar include the 3D winds and qualitative aerosol backscatter in the lower part of the atmosphere along with derived products that estimate turbulence quantities and the boundary layer mixing height. HRRR-smoke output is used to evaluate against the HALO lidar to compare any changes to the dynamical structure as smoke is advected into the view of the lidar. Furthermore, the timing and placement of the aerosol layer are compared semi-quantitatively with the HALO lidar to address the height of the smoke plume, whether smoke is mixed down to the surface in the same way as observed, and to examine how the mixing heights and surface radiation fields changed as smoke advected across the region.

Expanding beyond the HALO lidar in Washington DC, we will briefly evaluate the impact of advected smoke from the Canadian wildfires at selected Mesonet sites in New York where Doppler lidars were operating as well as various ceilometers located between New York and Washington DC in order to understand regional differences between what was observed versus what was predicted by HRRR-smoke. Thus, one of the principal aims of the study is to understand how long-range transport of smoke impacts air quality conditions across cities positioned at different distances from the Canadian wildfires, and to, where possible, address the response of the dynamics as a result of changes in the radiative forcing due to increased aerosol optical thickness.