Enviro-HIRLAM model estimates of elevated black carbon pollution over Ukraine resulted from forest fires

Abstract

Abstract. Biomass burning is one of the biggest sources of atmospheric black carbon (BC), which negatively impacts human health and contributes to climate forcing. In this work, we explore the horizontal and vertical variability of BC concentrations over Ukraine during wildfires in August 2010. Using the Enviro-HIRLAM modelling framework, the BC atmospheric transport was modelled for coarse, accumulation, and Aitken mode aerosol particles emitted by the wildfire. Elevated pollution levels were observed within the boundary layer. The influence of the BC emissions from the wildfire was identified up to 550 hPa level for the coarse and accumulation modes and at distances of about 2000 km from the fire areas. BC was mainly transported in the lowest 3 km layer and mainly deposited at night and in the morning hours due to the formation of strong surface temperature inversions. As modelling is the only available source of BC data in Ukraine, our results were compared with ground-level measurements of dust, which showed an increase in concentration of up to 73 % during wildfires in comparison to average values. The BC contribution was found to be 10 %–20 % of the total aerosol mass near the wildfires in the lowest 2 km layer. At a distance, BC contribution exceeded 10 % only in urban areas. In the areas with a high BC content represented by both accumulation and coarse modes, downwelling surface long-wave radiation increased up to 20 W m−2, and 2 m air temperature increased by 1–4 ∘C during the midday hours. The findings of this case study can help to understand the behaviour of BC distribution and possible direct aerosol effects during anticyclonic conditions, which are often observed in mid-latitudes in the summer and lead to wildfire occurrences.

Seamless Modeling of Direct and Indirect Aerosol Effects during April 2020 Wildfire Episode in Ukraine

“…Nevertheless, changes up to ±4 • C were detected at a local scale or during specific synoptic conditions. Our previous study, conducted during more severe wildfires in 2010 but at some distance from burning areas [31], showed similar changes in the 2 m air temperature, reaching ±3 • C. Ref. [33] described that opposite air temperature changes can be even more significant, reaching up to ±6 • C at the local scale.…”

“…Our results show that the aerosol effects influenced the meteorological parameters near the surface. Most of the earlier studies have reported cooling effects due to the aerosols emitted from the wildfires [18][19][20]31]. In general, an elevated aerosol content (with prevailing BC and OC compounds) caused slight cooling, with greater agreement with a fine spatial resolution.…”

“…Although wildfire emissions are often observed over the region of study, the vertical distribution of carbonaceous aerosols (BC and OC), ratio of their particle size, and other features can be different. For example, a previous case study performed using the Enviro-HIRLAM modeling system for 2010 wildfire events [31] showed numerous significant differences. While the accumulation mode was dominant in both the presented and previous studies, the concentrations of Aitken and coarse aerosol particles were the opposite.…”

“…Unfortunately, there are almost no observations of aerosol concentrations at the Ukrainian air quality network, which had already been discussed in [8,31]. Only total suspended coarse particle concentrations were available, but without size or chemical classification.…”

Potential Impacts of Forest Wildfires on Regional Water Quality: A Case Study of the "8·19" Forest Fire in Jiangjin, Chongqing

“…Notably, areas in proximity to the wildfire's origin recorded the highest average concentrations, peaking at 2.5μg/m 3 for BC and 15.0μg/m 3 for OM. Biomass combustion from wildfires is a significant source of atmospheric BC and OM (Savenets et al 2022;Coward et al 2022). The dispersion of ash containing BC and OM into the atmosphere, aided by rising air currents from wildfires, exhibits a lagged release.…”