Abstract Large particle size and thick coatings have been detected in pyrocumulonimbus (pyroCb) smoke injected into the lower stratosphere, enhancing both extinction and absorption of smoke. Here, we quantified how particle size and coating, via internal mixing of non‐absorbing species on black carbon, influence pyroCb smoke radiative forcing and stratospheric heating using core‐shell Mie calculations coupled with chemical transport and radiative transfer models. Airborne measurements indicate a number median radius of 0.25 μm for days‐old pyroCb smoke, larger than typical lower tropospheric smoke. This larger size approximately doubles aerosol extinction and enhances shortwave radiative forcing at the top of the atmosphere by 35%–60%, more consistent with satellite‐observed radiative fluxes following 2019–2020 Australian pyroCb event. Coating enhances stratospheric heating by 1–1.5 K, twice the enhancement caused by larger particle size, yielding better agreement with stratospheric temperature anomaly observed from satellite during the first 3 months after injection.
Chen et al. (Wed,) studied this question.