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Title: Evaluating simplified chemical mechanisms within present-day simulations of the Community Earth System Model version 1.2 with CAM4 (CESM1.2 CAM-chem): MOZART-4 vs. Reduced Hydrocarbon vs. Super-Fast chemistry

Abstract

While state-of-the-art complex chemical mechanisms expand our understanding of atmospheric chemistry, their sheer size and computational requirements often limit simulations to short lengths or ensembles to only a few members.Here we present and compare three 25-year present-day offline simulations with chemical mechanisms of different levels of complexity using the Community Earth System Model (CESM) Version 1.2 CAM-chem (CAM4): the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4) mechanism, the Reduced Hydrocarbon mechanism, and the Super-Fast mechanism. We show that,for most regions and time periods, differences in simulated ozone chemistry between these three mechanisms are smaller than the model–observation differences themselves. The MOZART-4 mechanism and the Reduced Hydrocarbon are in close agreement in their representation of ozone throughout the troposphere during all time periods (annual, seasonal, and diurnal). While the Super-Fast mechanism tends to have higher simulated ozone variability and differs from the MOZART-4 mechanism over regions of high biogenic emissions,it is surprisingly capable of simulating ozone adequately given its simplicity. We explore the trade-offs between chemical mechanism complexity and computational cost by identifying regions where the simpler mechanisms are comparable to the MOZART-4 mechanism and regions where they are not. The Super-Fast mechanism is 3 times as fast as themore » MOZART-4 mechanism, which allows for longer simulations or ensembles with more members that may not be feasible with the MOZART-4 mechanism given limited computational resources.« less

Authors:
 [1]; ORCiD logo [2];  [3];  [4]; ORCiD logo [4]; ORCiD logo [4]; ORCiD logo [5]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Center for Global Change Science, and Joint Program on the Science and Policy of Global Change
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Joint Program on the Science and Policy of Global Change, Inst. for Data, Systems, and Society, and Dept. of Earth, Atmospheric, and Planetary Sciences
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Center for Global Change Science, and Joint Program on the Science and Policy of Global Change, and Dept. of Earth, Atmospheric, and Planetary Sciences
  4. National Center for Atmospheric Research, Boulder, CO (United States). Atmospheric Chemistry Observations and Modeling Lab.
  5. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1502024
Report Number(s):
LLNL-JRNL-744047
Journal ID: ISSN 1991-9603; 898978
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Geoscientific Model Development (Online)
Additional Journal Information:
Journal Name: Geoscientific Model Development (Online); Journal Volume: 11; Journal Issue: 10; Journal ID: ISSN 1991-9603
Publisher:
European Geosciences Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Brown-Steiner, Benjamin, Selin, Noelle E., Prinn, Ronald, Tilmes, Simone, Emmons, Louisa, Lamarque, Jean-François, and Cameron-Smith, Philip. Evaluating simplified chemical mechanisms within present-day simulations of the Community Earth System Model version 1.2 with CAM4 (CESM1.2 CAM-chem): MOZART-4 vs. Reduced Hydrocarbon vs. Super-Fast chemistry. United States: N. p., 2018. Web. doi:10.5194/gmd-11-4155-2018.
Brown-Steiner, Benjamin, Selin, Noelle E., Prinn, Ronald, Tilmes, Simone, Emmons, Louisa, Lamarque, Jean-François, & Cameron-Smith, Philip. Evaluating simplified chemical mechanisms within present-day simulations of the Community Earth System Model version 1.2 with CAM4 (CESM1.2 CAM-chem): MOZART-4 vs. Reduced Hydrocarbon vs. Super-Fast chemistry. United States. doi:10.5194/gmd-11-4155-2018.
Brown-Steiner, Benjamin, Selin, Noelle E., Prinn, Ronald, Tilmes, Simone, Emmons, Louisa, Lamarque, Jean-François, and Cameron-Smith, Philip. Mon . "Evaluating simplified chemical mechanisms within present-day simulations of the Community Earth System Model version 1.2 with CAM4 (CESM1.2 CAM-chem): MOZART-4 vs. Reduced Hydrocarbon vs. Super-Fast chemistry". United States. doi:10.5194/gmd-11-4155-2018. https://www.osti.gov/servlets/purl/1502024.
@article{osti_1502024,
title = {Evaluating simplified chemical mechanisms within present-day simulations of the Community Earth System Model version 1.2 with CAM4 (CESM1.2 CAM-chem): MOZART-4 vs. Reduced Hydrocarbon vs. Super-Fast chemistry},
author = {Brown-Steiner, Benjamin and Selin, Noelle E. and Prinn, Ronald and Tilmes, Simone and Emmons, Louisa and Lamarque, Jean-François and Cameron-Smith, Philip},
abstractNote = {While state-of-the-art complex chemical mechanisms expand our understanding of atmospheric chemistry, their sheer size and computational requirements often limit simulations to short lengths or ensembles to only a few members.Here we present and compare three 25-year present-day offline simulations with chemical mechanisms of different levels of complexity using the Community Earth System Model (CESM) Version 1.2 CAM-chem (CAM4): the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4) mechanism, the Reduced Hydrocarbon mechanism, and the Super-Fast mechanism. We show that,for most regions and time periods, differences in simulated ozone chemistry between these three mechanisms are smaller than the model–observation differences themselves. The MOZART-4 mechanism and the Reduced Hydrocarbon are in close agreement in their representation of ozone throughout the troposphere during all time periods (annual, seasonal, and diurnal). While the Super-Fast mechanism tends to have higher simulated ozone variability and differs from the MOZART-4 mechanism over regions of high biogenic emissions,it is surprisingly capable of simulating ozone adequately given its simplicity. We explore the trade-offs between chemical mechanism complexity and computational cost by identifying regions where the simpler mechanisms are comparable to the MOZART-4 mechanism and regions where they are not. The Super-Fast mechanism is 3 times as fast as the MOZART-4 mechanism, which allows for longer simulations or ensembles with more members that may not be feasible with the MOZART-4 mechanism given limited computational resources.},
doi = {10.5194/gmd-11-4155-2018},
journal = {Geoscientific Model Development (Online)},
number = 10,
volume = 11,
place = {United States},
year = {2018},
month = {1}
}

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