Size-resolved simulations of the aerosol inorganic composition with the new hybrid dissolution solver HyDiS-1.0: description, evaluation and first global modelling results

Abstract

Abstract. The dissolution of semi-volatile inorganic gases such as ammonia and nitric acid into the aerosol aqueous phase has an important influence on the composition, hygroscopic properties, and size distribution of atmospheric aerosol particles. The representation of dissolution in global models is challenging due to inherent issues of numerical stability and computational expense. For this reason, simplified approaches are often taken, with many models treating dissolution as an equilibrium process. In this paper we describe the new dissolution solver HyDiS-1.0, which was developed for the global size-resolved simulation of aerosol inorganic composition. The solver applies a hybrid approach, which allows for some particle size classes to establish instantaneous gas-particle equilibrium, whereas others are treated time dependently (or dynamically). Numerical accuracy at a competitive computational expense is achieved by using several tailored numerical formalisms and decision criteria, such as for the time-and size-dependent choice between the equilibrium and dynamic approaches. The new hybrid solver is shown to have numerical stability across a wide range of numerical stiffness conditions encountered within the atmosphere. For ammonia and nitric acid, HyDiS-1.0 is found to be in excellent agreement with a fully dynamic benchmark solver. In the presence of sea salt aerosol, a somewhat larger bias is found under highly polluted conditions if hydrochloric acid is represented as a third semi-volatile species. We present first results of the solver's implementation into a global aerosol microphysics and chemistry transport model. We find that (1) the new solver predicts surface concentrations of nitrate and ammonium in reasonable agreement with observations over Europe, the USA, and East Asia, (2) models that assume gas-particle equilibrium will not capture the partitioning of nitric acid and ammonia into Aitken-mode-sized particles, and thus may be missing an important pathway through which secondary particles may grow to radiation-and cloudinteracting size, and (3) the new hybrid solver's computational expense is modest, at around 10 % of total computation time in these simulations.

Causes and importance of new particle formation in the present‐day and preindustrial atmospheres

“…The production rate of secondary organic aerosol that results is 14.2 Tg C yr −1 . Ammonia emissions from the EDGAR inventory are used to determine concentration fields in a dedicated TOMCAT model run employing the hybrid dissolution solver HyDiS-1.0 [Benduhn et al, 2016;Dunne et al, 2016]. These fields are then read into the GLOMAP model to determine ternary inorganic NPF rates.…”

Development and Evaluation of Chemistry‐Aerosol‐Climate Model CAM5‐Chem‐MAM7‐MOSAIC: Global Atmospheric Distribution and Radiative Effects of Nitrate Aerosol

“…Consequently, many previous global modeling studies of inorganic aerosols have adopted various ad hoc bulk equilibrium partitioning treatments for nitrate for either the entire aerosol size distribution or for only the fine aerosol mode while ignoring the coarse mode dust and/or sea-salt aerosols (Adams et al, 1999(Adams et al, , 2001An et al, 2019;Bauer et al, 2007;Bellouin et al, 2011;Bian et al, 2017;Gong et al, 2003;Li et al, 2015;Liao & Seinfeld, 2005;Liao et al, 2009;Metzger & Lelieveld, 2007;Mezuman et al, 2016;Myhre et al, 2006;Pye et al, 2009;Zhou et al, 2012). Several hybrid approaches have also been used in global models to reduce the computational cost by assuming equilibrium partitioning for the fine mode NH 4 NO 3 aerosol while using kinetic mass transfer for the coarse mode dust and/or sea-salt aerosols (Benduhn et al, 2016;Bian et al, 2017;Fairlie et al, 2010;Feng & Penner, 2007;Hauglustaine et al, 2014;Karydis et al, 2016;Pozzer et al, 2012;Pringle et al, 2010;Rodriguez & Dabdub, 2004;Xu & Penner, 2012). Although an improvement over the bulk equilibrium assumption, the hybrid approaches are still prone to significant errors and biases (Hu et al, 2008) and underestimate the contribution of HNO 3 to nanoparticle growth in inhomogeneous source environments (M. .…”

Current State of Atmospheric Aerosol Thermodynamics and Mass Transfer Modeling: A Review

“…Benduhn et al [283] introduced a hybrid scheme for surface mass transfer of semi-volatile species (HNO 3 , NH 3 and HCl). The hybrid approach attempts to avoid the numerical cost of explicitly solving stiff equations.…”