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Climate, variability, and climate sensitivity of “Middle Atmosphere” chemistry configurations of the Community Earth System Model Version 2, Whole Atmosphere Community Climate Model Version 6 (CESM2(WACCM6))
  • +11
  • Nicholas Alexander Davis,
  • Daniele Visioni,
  • Rolando R. Garcia,
  • Douglas Edward Kinnison,
  • Daniel R. Marsh,
  • Michael James Mills,
  • Jadwiga H. Richter,
  • Simone Tilmes,
  • Charles Bardeen,
  • Andrew Gettelman,
  • Anne A. Glanville,
  • Douglas G MacMartin,
  • Anne K. Smith,
  • Francis Vitt
Nicholas Alexander Davis
National Center for Atmospheric Research

Corresponding Author:[email protected]

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Daniele Visioni
Sibley School of Mechanical and Aerospace Engineering, Cornell University
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Rolando R. Garcia
National Center for Atmospheric Research (NCAR)
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Douglas Edward Kinnison
NCAR/CLAS
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Daniel R. Marsh
National Center for Atmospheric Research (UCAR)
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Michael James Mills
National Center for Atmospheric Research (UCAR)
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Jadwiga H. Richter
National Center for Atmospheric Research (UCAR)
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Simone Tilmes
National Center for Atmospheric Research (UCAR)
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Charles Bardeen
National Center for Atmospheric Research (UCAR)
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Andrew Gettelman
Pacific Northwest National Laboratory
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Anne A. Glanville
National Center for Atmospheric Research (UCAR)
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Douglas G MacMartin
Cornell University
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Anne K. Smith
National Center for Atmospheric Research (UCAR)
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Francis Vitt
National Center for Atmospheric Research (UCAR)
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Abstract

Simulating whole atmosphere dynamics, chemistry, and physics is computationally expensive. It can require high vertical resolution throughout the middle and upper atmosphere, as well as a comprehensive chemistry and aerosol scheme coupled to radiation physics. An unintentional outcome of the development of one of the most sophisticated and hence computationally expensive model configurations is that it often excludes a broad community of users with limited computational resources. Here, we analyze two configurations of the Community Earth System Model Version 2, Whole Atmosphere Community Climate Model Version 6 (CESM2(WACCM6)) with simplified “middle atmosphere” chemistry at nominal 1 and 2 degree horizontal resolutions. Using observations, a reanalysis, and direct model comparisons, we find that these configurations generally reproduce the climate, variability, and climate sensitivity of the 1 degree nominal horizontal resolution configuration with comprehensive chemistry. While the background stratospheric aerosol optical depth is elevated in the middle atmosphere configurations as compared to the comprehensive chemistry configuration, it is comparable between all configurations during volcanic eruptions. For any purposes other than those needing an accurate representation of tropospheric organic chemistry and secondary organic aerosols, these simplified chemistry configurations deliver reliable simulations of the whole atmosphere that require 35% to 86% fewer computational resources at nominal 1 and 2 degree horizontal resolution, respectively.