Abstract:
Biomass burning emits a large quantity of gaseous pollutants and aerosols into the atmosphere, which perturbs the regional
and global climate and has significant impacts on air quality and human health. In order to understand the temporal and
spatial distributions of biomass burning and its contribution to aerosol optical and radiative impacts, we examined fire emis sion data and its contribution to aerosol optical and radiative impacts over six major hot-spot continents/sub-continents
across the globe, namely North-Central (NC) Africa, South America, US-Hawaii, South Asia, South East Asia, and
Australia-New Zealand, using long-term satellites, ground-based and re-analysis data during 2000–2021. The selected six
sites contributed ∼70% of total global fire data. The classification of biomass burning, such as pre, active, and post burning
phases, was performed based on the Absorption Angstrom Exponent (AAE) estimated from 55 AERONET (AErosol RObotic
NETwork) stations. The study found the highest contribution of fire count (55 %) during the active burning phase followed
by post (36 %) and pre (8 %) burning phases. Such high fire counts were associated with high absorption aerosol optical
depth (AAOD) during the active fire event. Strong dominance of fine and coarse mode mixed aerosols were also observed
during active and post fire regimes. High AAOD and low Extinction Angstrom Exponent (EAE) over NC Africa during the
fire events suggested presence of mineral dust mixed with biomass burning aerosols. Brightness temperature, fire radiative
power and fire count were also dominated by the active burning followed by post and pre burning phases. The maximum
heating rate of 3.15 K day−1 was observed during the active fire events. The heating rate profile shows clear variations for
three different fire regimes with the highest value of 1.80 K day−1 at ∼750 hPa altitude during the active fire event.
