Cooling radiative forcing effect enhancement of atmospheric amines-mineral particle caused by heterogeneous uptake and oxidation

Abstract. Warming radiative forced effect (RFE) derived from atmospheric amines attracts lots of attentions because of their contributions to brown carbons. Herein, the enhanced influence of amines (methyl-, dimethyl-, and trimethylamine) on cooling RFE of mineral particles is first confirmed at visible wavelengths. Present results state heterogeneous uptake and oxidation reactions of atmospheric amines are feasible on mineral particle at clean/polluted conditions, which are proofed by related thermodynamics and kinetics data obtained using combined classical molecular dynamics and density function theory methods. Based on mineral particles, simple forcing efficiency (SFE) results explain that amine uptake induces at least 11.8 % – 29.5 % enhancement on cooling RFE of amine-mineral particles at visible wavelengths. After amines’ heterogeneous oxidation, oxidized amine-mineral particles’ cooling RFE are furthermore enhanced due to increased oxygen contents. Moreover, oxidized trimethylamine-mineral particle under clean condition shows 45.6 % – 47.1 % SFE increment at 400–600 nm, which is at least 13.5 % higher than that of itself under polluted condition, due to high-oxygen-content product formation through trimethylamine autoxidation. Our results suggest cooling RFE derived from atmospheric amines can be equally important to their warming RFE on atmosphere. It is necessary to update heterogeneous oxidation mechanism and kinetics data of amines in atmospheric model in order to accurately evaluate the whole RFE caused by amines on atmosphere.