Effect of an extreme smoke event on optical turbulence

Abstract

The Canadian wildfire event of 2023 caused periods of extreme smoke in the month of June in the Midwest and northeastern USA. Measurements taken at two different sites during this event were analyzed to understand how extreme smoke/ haze environments can affect atmospheric fluxes and hence optical turbulence in the surface layer. Instruments deployed at the Laser Experimental Range on Wright-Patterson Air Force Base recorded atmospheric parameters such as temperature, pressure, relative humidity, wind speed and optical turbulence at multiple heights in the surface layer and downwelling solar radiation. Aerosol measurements were also taken, and the optical properties/ chemical composition of the smoke aerosols were studied. From an instrumented tower at a New York State (NYS) Mesonet site in Voorheesville, NY, temperature data at two different heights, net radiation, downwelling solar radiation, sensible heat flux and optical turbulence information could be obtained. When compared to clear days right before the smoke event, the smoke days showed a significant reduction in downwelling solar radiation. This reduction in downwelling solar radiation caused a decrease in sensible heat flux and optical turbulence levels at both sites. The lapse rates of temperature and turbulence changed as well. Additionally, preliminary analysis of the Voorheesville data suggests that the statistics of turbulence was altered too. In the future, this aspect will be explored further, using smoke data from different sources and sites.