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Small impact of stratospheric dynamics and chemistry on the surface temperature of the Last Glacial Maximum in CESM2(WACCM6ma)
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  • Jiang Zhu,
  • Bette L Otto-Bliesner,
  • Esther C. Brady,
  • Rolando R. Garcia,
  • Michael James Mills,
  • Douglas Edward Kinnison,
  • Jean-Francois Lamarque
Jiang Zhu
National Center for Atmospheric Research

Corresponding Author:[email protected]

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Bette L Otto-Bliesner
National Center for Atmospheric Research (UCAR)
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Esther C. Brady
National Center for Atmospheric Research (UCAR)
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Rolando R. Garcia
National Center for Atmospheric Research (NCAR)
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Michael James Mills
National Center for Atmospheric Research (UCAR)
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Douglas Edward Kinnison
NCAR/CLAS
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Jean-Francois Lamarque
NCAR/UCAR
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Abstract

Stratospheric dynamics and chemistry can impact the tropospheric climate through changing radiatively active atmospheric constituents and stratosphere-troposphere interactions. The impact of stratospheric dynamics and chemistry on the Last Glacial Maximum (LGM) climate is not well studied and remains an uncertain aspect of glacial-interglacial climate change. Here we perform coupled LGM simulations using the Community Earth System Model version 2 (CESM2), with a high-top atmosphere—the Whole Atmosphere Community Climate Model version 6 with a middle atmosphere chemistry mechanism (WACCM6ma). The CESM2(WACCM6ma) LGM simulations show a weaker stratospheric circulation than the preindustrial, 10–35% less tropospheric ozone and 10–50% more ozone in the lower stratosphere. These stratospheric dynamics and chemistry changes cause slightly colder (by <5%) LGM surface and tropospheric temperatures than parallel simulations using a low-top atmosphere model without active chemistry. The results suggest that stratospheric dynamics and chemistry have little direct effect on the glacial-interglacial climate change.