Relative importance of gas uptake on aerosol and ground surfaces characterized by equivalent uptake coefficients Journal Article uri icon



  • Abstract. Quantifying the relative importance of gas uptake on the ground and aerosol surfaces helps to determine which processes should be included in atmospheric chemistry models. Gas uptake by aerosols is often characterized by an effective uptake coefficient (γeff), whereas gas uptake on the ground is usually described by a deposition velocity (Vd). For efficient comparison, we introduce an equivalent uptake coefficient (γeqv) at which the uptake flux of aerosols would equal that on the ground surface. If γeff is similar to or larger than γeqv, aerosol uptake is important and should be included in atmospheric models. In this study, we compare uptake fluxes in the planetary boundary layer (PBL) for different reactive trace gases (O3, NO2, SO2, N2O5, HNO3, H2O2), aerosol types (mineral dust, soot, organic aerosol, sea salt aerosol), environments (urban, agricultural land, Amazon forest, water body), seasons, and mixing heights. For all investigated gases, γeqv ranges from 10−6 ~ 10−4 in polluted urban environments to 10−4 ~ 10−1 under pristine forest conditions. In urban areas, aerosol uptake is relevant for all species (γeff ≥ γeqv) and should be considered in models. On the contrary, contributions of aerosol uptakes in Amazon forest are minor compared to the dry deposition. Phase state of aerosols could be one of the crucial factors influencing the uptake rates. Current models tend to underestimate the O3 uptake on liquid organic aerosols which can be important especially over regions with γeff ≥ γeqv. H2O2 uptakes on a variety of aerosols is yet to be measured at laboratory and evaluated. Given the fact that most models have considered their uptakes on the ground surface, we suggest also considering the N2O5 uptake by all types of aerosols, HNO3 and H2O2 uptakes by mineral dust, O3 uptake by liquid organic aerosols and NO2, SO2, HNO3 uptakes by sea salt aerosols in atmospheric models.;

publication date

  • April 2, 2019

has restriction

  • green

Date in CU Experts

  • June 15, 2021 3:59 AM

Full Author List

  • Li M; Su H; Li G; Ma N; Pöschl U; Cheng Y

author count

  • 6

Other Profiles