The impacts of biomass burning activities on convective systems over the Maritime Continent

Abstract

Abstract. Convective precipitation associated with Sumatra squall lines and diurnal rainfall over Borneo is an important weather feature of the Maritime Continent in Southeast Asia. Over the past few decades, biomass burning activities have been widespread during summertime over this region, producing massive fire aerosols. These additional aerosols, when brought into the atmosphere, besides influencing the local radiation budget through directly scattering and absorbing sunlight, can also act as cloud condensation nuclei or ice nuclei to alter convective clouds and precipitation over the Maritime Continent via so-called aerosol indirect effects. Based on 4-month simulations with or without biomass burning aerosols, conducted using the Weather Research and Forecasting model coupled with a chemistry module (WRF-Chem), we have investigated the aerosol–cloud interactions associated with biomass burning aerosols over the Maritime Continent. Results from selected cases of convective events have specifically shown the significant impact of fire aerosols on weak convections by their increasing of the quantities of hydrometeors and rainfall in both the Sumatra and Borneo regions. Statistical analysis over the fire season also suggests that fire aerosols have impacts on the nocturnal convections associated with the local anticyclonic circulation in western Borneo and weaken nocturnal rainfall intensity by about 9 %. Such an effect is likely to have come from the near-surface heating due to absorbing aerosols emitted from fires, which could weaken land breezes and thus the convergence of anticyclonic circulation.

Instant and delayed effects of March biomass burning aerosols over the Indochina Peninsula

“…Note that the choice of BB emission inventory could significantly affect the simulated aerosols due to the uncertainty in emission inventories introduced by a variety of measurements or analysis procedures, including detection of fire or areas burned, retrieval of fire-radiative power, emission factors, biome types, burning stages, and fuel consumption estimates (T. Pan et al, 2020). While the comparison of BB emission inventories is beyond the scope of this study, the FINN version 1.5 utilized in this study is widely used in BB aerosol modeling investigations (Lee and Wang, 2020;Wang et al, 2021;Takeishi and Wang, 2022); nevertheless, the potential impact of using different inventories needs to be kept in mind. To investigate the impacts of March BB aerosols on radiation, circulation, and precipitation, we conduct two groups of simulations with different BB emission scenarios and compare these results.…”

“…However, the initial suppressive effect of BB aerosols on rainfall can lead to convective invigoration by cold rain processes (Martins et al, 2009). BB aerosols may also enhance rainfall under certain conditions, which are highly dependent on factors such as the altitude and longevity of the smoke plume (Tummon et al, 2010;Ban-Weiss et al, 2012;Herbert et al, 2021), the atmospheric degree of instability (Gonçalves et al, 2015), and the diurnal cycle of the convective system (Lee and Wang, 2020;Herbert et al, 2021). The above-mentioned perturbations caused by BB aerosols can also affect largescale atmospheric circulation, thus changing the regional climate (Zhang et al, 2009;Lee et al, 2014;Jiang et al, 2020;Zhou et al, 2021).…”

Wildfire Smoke Influence on Cloud Water Chemical Composition at Whiteface Mountain, New York

“…Simulations using the Weather Research and Forecast modeling system with Chemistry (WRF‐Chem‐SMOKE) for northern Canada (Lu & Sokolik, 2013 ) and the western United States (Twohy et al., 2021 ) show that clouds significantly influenced by biomass burning smoke have increased cloud droplet number concentrations and decreased cloud droplet sizes. In this way, biomass burning particles can delay the onset of precipitation, affecting the lifetime, chemistry, and microphysical properties of clouds (Andreae et al., 2004 ; Ge et al., 2014 ; Grandey et al., 2016 ; Lee & Wang, 2020 ; Lu & Sokolik, 2013 ).…”

Notable impact of wildfires in the western United States on weather hazards in the central United States

“…Wildfires can affect severe convective storms and weather by releasing large amounts of aerosol particles ( 6 ) and sensible heat ( 7 ). The former can affect storm intensity and weather hazards through aerosol–cloud interactions ( 8 – 11 ). The latter modifies the environmental thermodynamics and can generate pyrocumulonimbus (pyroCb) clouds ( 12 – 17 ).…”

“…Studies of wildfire effects on severe convective storms and weather hazards focused on the pyroCb ( 7 , 12 – 17 ) or local wildfire aerosol effects ( 8 – 11 ). Few studies have explored the impact of long-range transported biomass burning aerosols on severe storms ( 18 – 20 ).…”