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Characterizing Convection Schemes Using Their Responses to Imposed Tendency Perturbations
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  • Yi-Ling Hwong,
  • Siwon Song,
  • Steven Sherwood,
  • Alison Stirling,
  • Catherine Rio,
  • Romain Roehrig,
  • Chimene Laure Daleu,
  • Robert Stephen Plant,
  • David Fuchs,
  • Penelope Maher,
  • Ludovic Touzé-Peiffer
Yi-Ling Hwong
Climate Change Research Centre, University of New South Wales

Corresponding Author:[email protected]

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Siwon Song
Center for Climate/Environment Change Prediction Research, Ewha Womans University
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Steven Sherwood
University of New South Wales
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Alison Stirling
UK Met Office
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Catherine Rio
Centre national des recherches météorologiques (CNRM), Université de Toulouse, Météo-France, CNRS
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Romain Roehrig
CNRM, Université de Toulouse, Météo-France, CNRS
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Chimene Laure Daleu
Reading University, UK
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Robert Stephen Plant
University of Reading
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David Fuchs
University of New South Wales
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Penelope Maher
University of Exeter
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Ludovic Touzé-Peiffer
Laboratoire de Météorologie Dynamique, Sorbonne Université, CNRS
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Abstract

Convection is usually parameterized in global climate models, and there are often large discrepancies between results obtained with different convection schemes. Conventional methods of comparing convection schemes using observational cases or directly in 3D models do not always clearly identify parameterization strengths and weaknesses. In this paper we evaluate the response of parameterizations to various perturbations rather than their behavior under particular strong forcing. We use the linear response function method proposed by Kuang (2010) to compare twelve physical packages in five atmospheric models using single-column model (SCM) simulations under idealized radiative-convective equilibrium conditions. The models are forced with anomalous temperature and moisture tendencies. The temperature and moisture departures from equilibrium are compared with published results from a cloud-resolving model (CRM). Results show that the procedure is capable of isolating the behavior of a convection scheme from other physics schemes. We identify areas of agreement but also substantial differences between convection schemes, some of which can be related to scheme design. Some aspects of the model linear responses are related to their RCE profiles (the relative humidity profile in particular), while others constitute independent diagnostics. All the SCMs show irregularities or discontinuities in behavior that are likely related to switches or thresholds built into the convection schemes, and which do not appear in the CRM. Our results highlight potential flaws in convection schemes and suggest possible new directions to explore for parameterization evaluation.
May 2021Published in Journal of Advances in Modeling Earth Systems volume 13 issue 5. 10.1029/2021MS002461