Light absorption enhancement (E_abs) of black carbon (BC) aerosol following atmospheric aging is one of the most challenging issues in the assessment of aerosol radiative forcing. BC E_abs is constrained by complex particle morphologies; however, large uncertainties continue to occur due to certain morphological parameters, including primary particle size. The values of E_abs during BC aging is quantified with diverse primary particle sizes using the superposition T-matrix method (STM). The results show that the uncertainty of absorption enhancement due to the primary particle size of fully aged BC particles ranges from ∼10% to 20%, while the uncertainties arising from varied BC volume-equivalent size and fractal dimension are ∼20-30% and ∼8-12%, respectively. The optical properties of BC particles with volume-equivalent radii ranging from 50 to 70 nm were largely influenced (up to ∼50%) by inappropriate assumptions regarding primary particle size. The specific assumptions of primary particle size in optical modeling plays an important role in constraining BC E_abs.

大气老化后黑碳（BC）气溶胶的光吸收增强（E _abs）是评估气溶胶辐射强迫中最具挑战性的问题之一。BC E _abs受复杂的粒子形态限制；然而，由于某些形态参数，包括初级粒径，继续存在较大的不确定性。E _abs的值在BC老化过程中，使用叠加T矩阵法（STM）用不同的初级粒径对老化进行了定量。结果表明，完全老化的BC粒子的初级粒径引起的吸收增强的不确定性在〜10％至20％的范围内，而BC体积当量尺寸和分形维数的变化引起的不确定性为〜20-30％，并且分别约为8-12％。体积等效半径范围从50到70 nm的BC颗粒的光学性质受到有关初级粒径的不适当假设的影响很大（最高约50％）。光学建模中初级粒径的具体假设在限制BC E _abs中起重要作用。