Origin of Smoke in the Record-Breaking Air-Pollution Event in New York, June 2023

During the fire season of 2023, extreme continuous wildfires in Canada exported smoke to distant areas. On June 6–8, record-breaking smoke concentrations impacted human health and the environment in New York City (NYC) and its surroundings. In this work, for the first time, we incorporate Lagrangian airmass trajectories with Copernicus Atmospheric Monitoring Service (CAMS) forecasts to trace back the origin of the smoke in NYC and identify the weather systems governing its transport. We locate the main smoke plume which originated from fires in Quebec. The smoke traveled at a height of about 500 hPa southward and descended slantwise to NYC behind a deep cyclone over the east coast. A second peak in smoke concentration in NYC emerged by air that circulated around the cyclone back to the city, collecting smoke again from the fires in Quebec. Smoke from the major fires in western Canada did not contribute significantly to the NYC event but was transported at tropopause level toward Europe. The findings highlight the critical role of synoptic-scale systems in the transport of wildfire smoke.