Uncertainties of Simulated Aerosol Direct Radiative Effect Induced by Aerosol Chemical Components: A Measurement‐Based Perspective From Urban‐Forest Transition Region in East China

Abstract Difference and uncertainty of the aerosol radiative effects were quantified using the Santa Barbara DISORT Atmospheric Radiative Transfer model and multiple aerosol observation data sets from urban‐forest transition region. The secondary transformed carbonaceous aerosol components and biogenic secondary organic aerosol (BSOA) tracers have dominated over all other components (with a higher concentration in wet season) in terms of its impact on the aerosol radiative forcing (ARF). The averaged organic carbon (OC) and BSOA tracers increased from 13.3 ± 4.99 μg/m3, 29.5 ± 10.7 ng m−3 to 17.3 ± 4.47 μg/m3, 78.7 ± 43.7 ng m−3 in the dry and wet seasons, respectively. The corresponding root mean square errors of single scattering albedo and radiative forcing at the top of the atmosphere have increased by 8.4% and 16.9%. From the dry season to the wet season, the drastically aerosol composition and types variations caused the aerosol radiation effect reverse from cooling to heating. The increase in carbonaceous aerosols and BSOA transformed by forests in the wet season weakened the cooling effects. Driven by multiple factors, such as meteorological conditions, emission sources, and the mixed state of particulate matters, the transport patterns of air masses exhibit completely opposite effects to the ARF. Affected by the source location, wet deposition rate and components residence time, the uncertainty of ARF caused by long‐distance transport of aerosols is 68% higher than that of local aerosol situations under the condition of similar aerosol composition distributions. At similar transport distances, stronger aerosol secondary transformation increases the uncertainty of ARF by 20%.