A framework for expanding aqueous chemistry in the Community Multiscale Air Quality (CMAQ) model version 5.1

Kathleen M Fahey; Annmarie G Carlton; Havala O T Pye; Jaemeen Baek; William T Hutzell; Charles O Stanier; Kirk R Baker; K Wyat Appel; Mohammed Jaoui; John H Offenberg

doi:10.5194/gmd-10-1587-2017

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A framework for expanding aqueous chemistry in the Community Multiscale Air Quality (CMAQ) model version 5.1

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A framework for expanding aqueous chemistry in the Community Multiscale Air Quality (CMAQ) model version 5.1

Kathleen M Fahey, Annmarie G Carlton, Havala O T Pye, Jaemeen Baek, William T Hutzell, Charles O Stanier, Kirk R Baker, K Wyat Appel, Mohammed Jaoui and John H Offenberg

Geoscientific model development, Vol.10(4), pp.1587-1605

2017

DOI: 10.5194/gmd-10-1587-2017

PMCID: PMC6104655

PMID: 30147851

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Abstract

This paper describes the development and implementation of an extendable aqueous-phase chemistry option (AQCHEM -KMT(I)) for the Community Multiscale Air Quality (CMAQ) modeling system, version 5.1. Here, the Kinetic PreProcessor (KPP), version 2.2.3, is used to generate a Rosenbrock solver (Rodas3) to integrate the stiff system of ordinary differential equations (ODEs) that describe the mass transfer, chemical kinetics, and scavenging processes of CMAQ clouds. CMAQ's standard cloud chemistry module (AQCHEM) is structurally limited to the treatment of a simple chemical mechanism. This work advances our ability to test and implement more sophisticated aqueous chemical mechanisms in CMAQ and further investigate the impacts of microphysical parameters on cloud chemistry. Box model cloud chemistry simulations were performed to choose efficient solver and tolerance settings, evaluate the implementation of the KPP solver, and assess the direct impacts of alternative solver and kinetic mass transfer on predicted concentrations for a range of scenarios. Month-long CMAQ simulations for winter and summer periods over the US reveal the changes in model predictions due to these cloud module updates within the full chemical transport model. While monthly average CMAQ predictions are not drastically altered between AQCHEM and AQCHEM-KMT, hourly concentration differences can be significant. With added in-cloud secondary organic aerosol (SOA) formation from biogenic epoxides (AQCHEM-KMTI), normalized mean error and bias statistics are slightly improved for 2-methyltetrols and 2-methylglyceric acid at the Research Triangle Park measurement site in North Carolina during the Southern Oxidant and Aerosol Study (SOAS) period. The added in-cloud chemistry leads to a monthly average increase of 11-18 % in "cloud" SOA at the surface in the eastern United States for June 2013.

Details

Title: Subtitle: A framework for expanding aqueous chemistry in the Community Multiscale Air Quality (CMAQ) model version 5.1
Creators: Kathleen M Fahey - Research Triangle Park
Annmarie G Carlton - University of California, Irvine
Havala O T Pye - Research Triangle Park
Jaemeen Baek - University of Iowa
William T Hutzell - Research Triangle Park
Charles O Stanier - University of Iowa
Kirk R Baker - Research Triangle Park
K Wyat Appel - Research Triangle Park
Mohammed Jaoui - Research Triangle Park
John H Offenberg - Research Triangle Park
Resource Type: Journal article
Publication Details: Geoscientific model development, Vol.10(4), pp.1587-1605
DOI: 10.5194/gmd-10-1587-2017
PMID: 30147851
PMCID: PMC6104655
NLM abbreviation: Geosci Model Dev
ISSN: 1991-959X
eISSN: 1991-9603
Language: English
Date published: 2017
Academic Unit: Chemical and Biochemical Engineering
Record Identifier: 9984197333502771

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