IMPACT, the LLNL 3‐D global atmospheric chemical transport model for the combined troposphere and stratosphere: Model description and analysis of ozone and other trace gases

Abstract

[1] We present a global chemical transport model called the Integrated Massively Parallel Atmospheric Chemical Transport (IMPACT) model. This model treats chemical and physical processes in the troposphere, the stratosphere, and the climatically critical tropopause region, allowing for physically based simulations of past, present, and future ozone and its precursors. The model is driven by meteorological fields from general circulation models (GCMs) or assimilated fields representing particular time periods. It includes anthropogenic and natural emissions, advective and convective transport, vertical diffusion, dry deposition, wet scavenging, and photochemistry. Simulations presented here use meteorological fields from the National Center for Atmospheric Research (NCAR) Middle Atmospheric Community Climate Model, Version 3 (MACCM3). IMPACT simulations of radon/lead are compared to observed vertical profiles and seasonal cycles. IMPACT results for a full chemistry simulation, with approximately 100 chemical species and 300 reactions representative of a mid-1990s atmosphere, are presented. The results are compared with surface, satellite, and ozonesonde observations. The model calculates a total annual flux from the stratosphere of 663 Tg O 3 /year, and a net in situ tropospheric photochemical source (that is, production minus loss) of 161 Tg O 3 /year, with 826 Tg O 3 /year dry deposited. NO x is overpredicted in the lower midlatitude stratosphere, perhaps because model aerosol surface densities are lower than actual values or the NO x to NO y conversion rate is underpredicted. Analysis of the free radical budget shows that ozone and NO y abundances are simulated satisfactorily, as are HO x catalytic cycles and total production and removal rates for ozone.

Errors and improvements in the use of archived meteorological data for chemical transport modeling: an analysis using GEOS-Chem v11-01 driven by GEOS-5 meteorology

“…GEOS operational meteorological products have been widely used for off-line CTM applications including by the University of Maryland (UMD) CTM (Allen et al, 1996), GEOS-Chem , Global Modeling Initiative (GMI) CTM (Douglass et al, 1999(Douglass et al, , 2004, Integrated Massively Parallel Atmospheric Chemical Transport (IM-PACT) model (Rotman et al, 2004), MOZART (Emmons et al, 2010), CAM-Chem (Lamarque et al, 2012), and the GEOS CTM . Chemical transport simulations can also be performed online within the GEOS-5 GCM (Colarco et al, 2010;Oman and Douglass, 2014;Long et al, 2015;Strode et al, 2015;Li et al, 2016).…”

Role of dust alkalinity in acid mobilization of iron

“…We use an aerosol chemistry version of the Integrated Massively Parallel Atmospheric Chemical Transport (IMPACT) model (Rotman et al, 2004;Liu et al, 2005;Feng and Penner, 2007;Ito et al, 2009) as a framework for this study. The model is driven by assimilated meteorological fields for the year of 2001 from the Goddard Earth Observation System (GEOS) of the NASA Global Modeling and Assimilation Office (GMAO).…”

Heterogeneous Chemistry: Understanding Aerosol/Oxidant Interactions

“…A global aerosol and chemistry transport model, the University of Michigan (UMICH) version of the Lawrence Livermore National Laboratory (LLNL) IMPACT model [Liu and Penner, 2002;Feng et al, 2004;Rotman et al, 2004;Liu et al, submitted, 2005], was used as the framework for this study. The spatial resolution of the IMPACT model is 2° latitude by 2.5° longitude in the horizontal, with 26 layers in the vertical from the surface to 0.1 hPa (the mean pressure levels are 994,971,930,875,813,745,675,605,537,472,410,353,302,258,220,187,158,133,112,94.1,79.3,67.0,56.7,37.7,14.3,and 2.64 hPa).…”

“…The cumulus mass flux and convective cloud detrainment used in the scheme are derived from the DAO meteorological fields. A full description of the transport and deposition schemes is given in Rotman et al [2004] for the original IMPACT model. [Penner et al, 1994].…”