Black carbon and secondary brown carbon, the dominant light absorption and direct radiative forcing contributors of the atmospheric aerosols over the Tibetan Plateau

Black carbon (BC), primary brown carbon (BrC_pri), and secondary brown carbon (BrC_sec) are important light-absorbing aerosol. BC and BrC from the surrounding area can reach the Tibetan Plateau (TP) and influence climate change and glacial melting. Here, we presented a study of the light absorption, radiative forcing, and potential source areas of BC and BrC over the northeastern, central, and southwestern TP. The higher light absorption was observed in the northeastern and southwestern sites compared to the central TP site. The major carbonaceous light-absorbing was attributed to BC with the percentages of 65%, 56%, and 82% in Ngari, Qinghai Lake, and Beiluhe, respectively. The heighten contribution of BrC_sec to total light absorption indicated the importance of BrC_sec in the TP, especially in the northeastern and southwestern areas. The BrC_sec radiative forcings relative to BC were much higher than those of BrC_pri. The potential BC and BrC_pri source distributions were obtained.黑碳（Black carbon，BC）、一次棕碳（primary brown carbon，BrC_pri）与二次棕碳（secondary brown carbon，BrC_sec）均为重要的吸光气溶胶。周边区域的黑碳与棕碳可输送至青藏高原（Tibetan Plateau，TP），并对气候变化及冰川消融产生影响。本研究针对青藏高原东北部、中部与西南部区域的BC与BrC吸光特性、辐射强迫及潜在源区开展研究。相较于TP中部监测站点，东北部与西南部监测站点的吸光水平更高。各区域主要的吸光含碳组分均为BC，其中阿里、青海湖与北麓河的占比分别为65%、56%与82%。二次棕碳对总吸光的贡献占比提升，体现出BrC_sec在TP区域的重要性，尤其在东北部与西南部地区。相较于BC，BrC_sec的辐射强迫远高于BrC_pri。本研究明确了BC与BrC_pri的潜在源区分布特征。