M7: An efficient size‐resolved aerosol microphysics module for large‐scale aerosol transport models

Abstract

[1] An aerosol model (M7) designed to be coupled to general circulation models (GCM) and chemistry transport models (CTM) is described. In M7 the aerosol population is divided into two types of particles: mixed, or water-soluble particles, and insoluble particles. The particles are represented by seven classes, using a ''pseudomodal'' approach. Four classes are for the mixed particles representing nucleation, Aitken, accumulation, and coarse mode, and three are for the insoluble (Aitken, accumulation, and coarse mode). The components considered are mineral dust, black carbon (BC) and primary organic carbon (OC), sulfate, and sea salt. The aerosol dynamic processes in M7 include nucleation, coagulation, and condensation of sulfuric acid. Mixed particles are formed from insoluble particles by coagulation and condensation. The integration scheme is computationally very efficient. The model has been tested against the analytical solution and a sectional model for the formation of SO 4 /BC mixed particles, evaluating the mixing by condensation and coagulation. Furthermore, M7 has been run in free tropospheric conditions and compared to aircraft observations. M7 has proven to be accurate and fast enough to be included in a GCM or CTM.

Aerosol distribution over Europe: a model evaluation study with detailed aerosol microphysics

“…The REMOTE model (Langmann, 2000) extended by the aerosol modal microphysics (Vignati et al, 2004) is able to reasonably reproduce measured meteorological and trace species quantities over Europe, e.g. precipitation, the amount and variability of wet deposition fluxes of sea salt and sulfate, and trace species concentration in surface air.…”

“…Each mode can be described by three moments: aerosol number N, number median radius r, and standard deviation σ . Standard deviations are prescribed in M7 (Vignati et al, 2004), so that the median radius of each mode can be calculated from the corresponding aerosol number and aerosol mass, which are transported as 25 tracers (Table 1). Thus, the total number of transported trace species in RE-MOTE is 63, with 38 of these participating in photochemical transformations (Langmann, 2000).…”

“…For the determination of aerosol dynamics and thermodynamics, we implemented the M7 module, which is described in detail in Vignati et al (2004) and Stier et al (2005), so that we only provide a brief description here. The aerosol dynamical processes in M7 include nucleation, coagulation and condensation.…”

“…Jacobson, 2001, Gong et al, 2003 reach generally a higher accuracy compared with the modal approach (Zhang et al, 1999) but are computationally more demanding. We have chosen the modal aerosol microphysical approach of M7 (Vignati et al, 2004) to extend the regional online climate-chemistry/aerosol model REMOTE (Langmann, 2000;. Beside the computational efficiency of the modal approach, the motivation was to develop a regional climate-chemistry/aerosol model comparable to the global ECHAM5-HAM model (Stier et al, …”

“…New efficient approaches to determine aerosol chemical composition, size distribution and microphysical interactions with a modal concept (e.g. Ackermann et al, 1998;Vignati et al, 2004) have been incorporated in climate models (e.g. Grell et al, 2005;Lauer et al, 2005;Stier et al, 2005).…”