Description and evaluation of GLOMAP-mode: a modal global aerosol microphysics model for the UKCA composition-climate model

Abstract

A new version of the Global Model of Aerosol Processes (GLOMAP) is described, which uses a two-moment modal aerosol scheme rather than the original two-moment bin scheme. GLOMAP-mode simulates the multi-component global aerosol, resolving sulphate, sea-salt, dust, black carbon (BC) and particulate organic matter (POM), the latter including primary and biogenic secondary POM. Aerosol processes are simulated in a size-resolved manner including primary emissions, secondary particle formation by binary homogeneous nucleation of sulphuric acid and water, particle growth by coagulation, condensation and cloud-processing and removal by dry deposition, in-cloud and below-cloud scavenging. A series of benchmark observational datasets are assembled against which the skill of the model is assessed in terms of normalised mean bias (<i>b</i>) and correlation coefficient (<i>R</i>). Overall, the model performs well against the datasets in simulating concentrations of aerosol precursor gases, chemically speciated particle mass, condensation nuclei (CN) and cloud condensation nuclei (CCN). Surface sulphate, sea-salt and dust mass concentrations are all captured well, while BC and POM are biased low (but correlate well). Surface CN concentrations compare reasonably well in free troposphere and marine sites, but are underestimated at continental and coastal sites related to underestimation of either primary particle emissions or new particle formation. The model compares well against a compilation of CCN observations covering a range of environments and against vertical profiles of size-resolved particle concentrations over Europe. The simulated global burden, lifetime and wet removal of each of the simulated aerosol components is also examined and each lies close to multi-model medians from the AEROCOM model intercomparison exercise

Clouds and Aerosols

“…The aerosol mixing state can alter particle size distribution and hygroscopicity and hence the aerosol optical properties and ability to act as CCN (Wex et al, 2010). Global aerosol models can now approximate the aerosol mixing state using size-resolving bin or modal schemes (e.g., Stier et al, 2005;Kim et al, 2008;Mann et al, 2010).…”

Fires increase Amazon forest productivity through increases in diffuse radiation

“…We simulated aerosol using the 3-D GLObal Model of Aerosol Processes (GLOMAP) [Mann et al, 2010]. The aerosol size distribution is simulated using a two-moment modal scheme.…”

Low sensitivity of cloud condensation nuclei to changes in the sea-air flux of dimethyl-sulphide

“…In this version of the model (GLOMAP-mode) the particle size distribution is represented using a two-moment (mass and number) modal scheme with log-normal modes. The model is described in detail in Mann et al (2010) and contains internal mixtures of sulphate, sea spray, elemental carbon (EC) and organic carbon (OC) (including secondary organics), and dust. Manktelow et al (2010) find that the impact of dust on sulphate aerosol is small during a large dust storm.…”

“…We use the Global Model of Aerosol Processes, GLOMAP (Spracklen et al, 2005;Manktelow et al, 2007;Mann et al, 2010) in the TOMCAT chemical transport model (Chipperfield, 2006). GLOMAP (in TOMCAT) is driven by European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-40 meteorology (Uppala et al, 2005).…”