scholarly journals Implementation and evaluation of an array of chemical solvers in the Global Chemical Transport Model GEOS-Chem

2009 ◽  
Vol 2 (2) ◽  
pp. 89-96 ◽  
Author(s):  
P. Eller ◽  
K. Singh ◽  
A. Sandu ◽  
K. Bowman ◽  
D. K. Henze ◽  
...  
Keyword(s):  
Transport Model ◽  
Chemical Transport ◽  
Chemical Mechanism ◽  
Chemical Transport Model ◽  
Simulation Code ◽  
Programming Effort ◽  
Efficient Code ◽  
Global Chemical Transport Model ◽  
And Performance ◽  
Continuous Adjoint

Abstract. This paper discusses the implementation and performance of an array of gas-phase chemistry solvers for the state-of-the-science GEOS-Chem global chemical transport model. The implementation is based on the Kinetic PreProcessor (KPP). Two perl parsers automatically generate the needed interfaces between GEOS-Chem and KPP, and allow access to the chemical simulation code without any additional programming effort. This work illustrates the potential of KPP to positively impact global chemical transport modeling by providing additional functionality as follows. (1) The user can select a highly efficient numerical integration method from an array of solvers available in the KPP library. (2) KPP offers a wide variety of user options for studies that involve changing the chemical mechanism (e.g., a set of additional reactions is automatically translated into efficient code and incorporated into a modified global model). (3) This work provides access to tangent linear, continuous adjoint, and discrete adjoint chemical models, with applications to sensitivity analysis and data assimilation.

scholarly journals Implementation and evaluation of an array of chemical solvers in a global chemical transport model

2009 ◽  
Vol 2 (1) ◽  
pp. 185-207 ◽  
Author(s):  
P. Eller ◽  
K. Singh ◽  
A. Sandu ◽  
K. Bowman ◽  
D. K. Henze ◽  
...  
Keyword(s):  
Transport Model ◽  
Chemical Transport ◽  
Chemical Mechanism ◽  
Chemical Transport Model ◽  
Simulation Code ◽  
Programming Effort ◽  
Efficient Code ◽  
Global Chemical Transport Model ◽  
And Performance ◽  
Continuous Adjoint

Abstract. This paper discusses the implementation and performance of an array of gas-phase chemistry solvers for the state-of-the-science GEOS-Chem global chemical transport model. The implementation is based on the Kinetic PreProcessor (KPP). Two perl parsers automatically generate the needed interfaces between GEOS-Chem and KPP, and allow access to the chemical simulation code without any additional programming effort. This work illustrates the potential of KPP to positively impact global chemical transport modeling by providing additional functionality as follows. (1) The user can select a highly efficient numerical integration method from an array of solvers available in the KPP library. (2) KPP offers extreme flexibility for studies that involve changing the chemical mechanism (e.g., a set of additional reactions is automatically translated into efficient code and incorporated into a modified global model). (3) This work provides immediate access to tangent linear, continuous adjoint, and discrete adjoint chemical models, with applications to sensitivity analysis and data assimilation.

scholarly journals Tagged ozone mechanism for MOZART-4, CAM-chem and other chemical transport models

2012 ◽  
Vol 5 (6) ◽  
pp. 1531-1542 ◽  
Author(s):  
L. K. Emmons ◽  
P. G. Hess ◽  
J.-F. Lamarque ◽  
G. G. Pfister
Keyword(s):  
Transport Model ◽  
Stratospheric Ozone ◽  
Chemical Transport ◽  
Chemical Mechanism ◽  
Chemical Transport Model ◽  
Transport Models ◽  
Chemical Tracers ◽  
Source Contributions ◽  
The Difference ◽  
No Emissions

Abstract. A procedure for tagging ozone produced from NO sources through updates to an existing chemical mechanism is described, and results from its implementation in the Model for Ozone and Related chemical Tracers (MOZART-4), a global chemical transport model, are presented. Artificial tracers are added to the mechanism, thus, not affecting the standard chemistry. The results are linear in the troposphere, i.e., the sum of ozone from individual tagged sources equals the ozone from all sources to within 3% in zonal mean monthly averages. In addition, the tagged ozone is shown to equal the standard ozone, when all tropospheric sources are tagged and stratospheric input is turned off. The stratospheric ozone contribution to the troposphere determined from the difference between total ozone and ozone from all tagged sources is significantly less than estimates using a traditional stratospheric ozone tracer (8 vs. 20 ppbv at the surface). The commonly used technique of perturbing NO emissions by 20% in a region to determine its ozone contribution is compared to the tagging technique, showing that the tagged ozone is 2–4 times the ozone contribution that was deduced from perturbing emissions. The ozone tagging described here is useful for identifying source contributions based on NO emissions in a given state of the atmosphere, such as for quantifying the ozone budget.

scholarly journals Description and evaluation of the Model for Ozone and Related chemical Tracers, version 4 (MOZART-4)

2010 ◽  
Vol 3 (1) ◽  
pp. 43-67 ◽  
Author(s):  
L. K. Emmons ◽  
S. Walters ◽  
P. G. Hess ◽  
J.-F. Lamarque ◽  
G. G. Pfister ◽  
...  
Keyword(s):  
Transport Model ◽  
Source Code ◽  
Chemical Mechanism ◽  
Chemical Transport Model ◽  
Chemical Tracers ◽  
Photolysis Frequencies ◽  
Community Data ◽  
Data Portal ◽  
Global Chemical Transport Model ◽  
Hydrocarbon Chemistry

Abstract. The Model for Ozone and Related chemical Tracers, version 4 (MOZART-4) is an offline global chemical transport model particularly suited for studies of the troposphere. The updates of the model from its previous version MOZART-2 are described, including an expansion of the chemical mechanism to include more detailed hydrocarbon chemistry and bulk aerosols. Online calculations of a number of processes, such as dry deposition, emissions of isoprene and monoterpenes and photolysis frequencies, are now included. Results from an eight-year simulation (2000–2007) are presented and evaluated. The MOZART-4 source code and standard input files are available for download from the NCAR Community Data Portal (http://cdp.ucar.edu).

scholarly journals Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model

2013 ◽  
Vol 13 (8) ◽  
pp. 21455-21505
Author(s):  
E. Emili ◽  
B. Barret ◽  
S. Massart ◽  
E. Le Flochmoen ◽  
A. Piacentini ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Chemical Transport ◽  
Free Troposphere ◽  
Chemical Transport Model ◽  
Ozone Monitoring Instrument ◽  
Global Chemical Transport Model ◽  
The Impact

Abstract. Accurate and temporally resolved fields of free-troposphere ozone are of major importance to quantify the intercontinental transport of pollution and the ozone radiative forcing. In this study we examine the impact of assimilating ozone observations from the Microwave Limb Sounder (MLS) and the Infrared Atmospheric Sounding Interferometer (IASI) in a global chemical transport model (MOdèle de Chimie Atmosphérique à Grande Échelle, MOCAGE). The assimilation of the two instruments is performed by means of a variational algorithm (4-D-VAR) and allows to constrain stratospheric and tropospheric ozone simultaneously. The analysis is first computed for the months of August and November 2008 and validated against ozone-sondes measurements to verify the presence of observations and model biases. It is found that the IASI Tropospheric Ozone Column (TOC, 1000–225 hPa) should be bias-corrected prior to assimilation and MLS lowermost level (215 hPa) excluded from the analysis. Furthermore, a longer analysis of 6 months (July–August 2008) showed that the combined assimilation of MLS and IASI is able to globally reduce the uncertainty (Root Mean Square Error, RMSE) of the modeled ozone columns from 30% to 15% in the Upper-Troposphere/Lower-Stratosphere (UTLS, 70–225 hPa) and from 25% to 20% in the free troposphere. The positive effect of assimilating IASI tropospheric observations is very significant at low latitudes (30° S–30° N), whereas it is not demonstrated at higher latitudes. Results are confirmed by a comparison with additional ozone datasets like the Measurements of OZone and wAter vapour by aIrbus in-service airCraft (MOZAIC) data, the Ozone Monitoring Instrument (OMI) total ozone columns and several high-altitude surface measurements. Finally, the analysis is found to be little sensitive to the assimilation parameters and the model chemical scheme, due to the high frequency of satellite observations compared to the average life-time of free-troposphere/low-stratosphere ozone.

MOZART, a global chemical transport model for ozone and related chemical tracers: 2. Model results and evaluation

1998 ◽  
Vol 103 (D21) ◽  
pp. 28291-28335 ◽  
Author(s):  
D. A. Hauglustaine ◽  
G. P. Brasseur ◽  
S. Walters ◽  
P. J. Rasch ◽  
J.-F. Müller ◽  
...  
Keyword(s):  
Transport Model ◽  
Chemical Transport ◽  
Chemical Transport Model ◽  
Chemical Tracers ◽  
Global Chemical Transport Model

scholarly journals The contribution of plume-scale nucleation to global and regional aerosol and CCN concentrations: evaluation and sensitivity to emissions changes

2014 ◽  
Vol 14 (24) ◽  
pp. 13661-13679 ◽  
Author(s):  
R. G. Stevens ◽  
J. R. Pierce
Keyword(s):  
Power Plant ◽  
Particle Number ◽  
Transport Model ◽  
Chemical Transport ◽  
Nox Emissions ◽  
Size Distributions ◽  
Chemical Transport Model ◽  
Global Chemical Transport Model ◽  
First Time ◽  
Particle Formation And Growth

Abstract. We implement the Predicting Particles Produced in Power-Plant Plumes (P6) sub-grid sulphate parameterization for the first time into a global chemical-transport model with online aerosol microphysics, the GEOS-Chem-TOMAS model. Compared to simulations using two other previous treatments of sub-grid sulphate, simulations using P6 sub-grid sulphate predicted similar or smaller increases (depending on other model assumptions) in globally, annually averaged concentrations of particles larger than 80 nm (N80). We test in simulations using P6 sub-grid sulphate the sensitivity of particle number concentrations to changes in SO2 or NOx emissions to represent recent emissions control changes. For global increases of 50% in emissions of either SO2 or NOx, or both SO2 and NOx, we find that globally, annually averaged N80 increase by 9.00, 1.47, or 10.24% respectively. However, both sub-grid and grid-resolved processes contribute to these changes. Finally, we compare the model results against observations of particle number concentrations. Compared with previous treatments of sub-grid sulphate, use of the P6 parameterization generally improves correlation with observed particle number concentrations. The P6 parameterization is able to resolve spatial heterogeneity in new-particle formation and growth that cannot be resolved by any constant assumptions about sub-grid sulphate. However, the differences in annually averaged aerosol size distributions due to the treatment of sub-grid sulphate at the measurement sites examined here are too small to unambiguously establish P6 as providing better agreement with observations.

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