Impacts of Maritime Continent Forest and Peat Fires on Regional Air Quality During 2019 CAMP²Ex Using MUSICAv0

The NASA Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP²Ex) field campaign from 24 August to 05 October 2019 observed a complex mixture of aerosols—biomass burning smoke transported from Maritime Continent (MC)/Indonesia fires to the Philippines and Metro Manila's urban pollution. The in situ and remote sensing aerosol measurements from CAMP²Ex plus aerosol retrievals from the Advanced Himawari Imager (AHI) provide a unique data set for characterizing the complex aerosol regimes and their regional air quality (AQ) impacts. We conducted two Multi-Scale Infrastructure for Chemistry and Aerosols (MUSICAv0) simulations using specified oxidants during the CAMP²Ex period: a Control experiment including only open burning emissions and Exp01 adding below-ground peat burning emissions. Both simulations employ variable resolution grids (∼14 km over the MC fires, ∼7 km over Luzon, Philippines). Here, we evaluate MUSICAv0's ability to represent transported smoke and local pollution and quantify the contribution of peat burning emissions to the observed aerosol burden. MUSICAv0 Control underestimates AOD across the region, with the largest biases over peat burning areas. Adding peat emissions improves regional AOD_mean by 26%. However, both simulations underpredict oceanic and downwind aerosol burden. Case studies of dense Borneo burning (16 September) and the Metro Manila urban plume (04 October) show that MUSICAv0 represents key transport and vertical structures of smoke and urban pollution but overestimates black carbon and secondary organic aerosol production. These findings highlight MUSICAv0's capability in multi-scale modeling of aerosols in the tropics, and motivate future improvements to emissions, plume rise, and aerosol representation.