Preprints
https://doi.org/10.5194/gmd-2021-413
https://doi.org/10.5194/gmd-2021-413

Submitted as: model evaluation paper 16 Dec 2021

Submitted as: model evaluation paper | 16 Dec 2021

Review status: this preprint is currently under review for the journal GMD.

Assessment of the sea surface temperature diurnal cycle in CNRM-CM6-1 based on its 1D coupled configuration

Aurore Voldoire1, Romain Roehrig1, Hervé Giordani1, Robin Waldman1, Yunyan Zhang2, Shaocheng Xie2, and Marie-Nöelle Bouin1,3 Aurore Voldoire et al.
  • 1CNRM, University of Toulouse, Météo-France, CNRS, Toulouse, France
  • 2Lawrence Livermore National Laboratory, Livermore, California, USA
  • 3Univ. Brest, CNRS, IRD, Ifremer, Laboratoire d’Océanographie Physique et Spatiale (LOPS), IUEM, 29840 Brest, France

Abstract. A single column version of the CNRM-CM6-1 global climate model has been developed to ease development and validation of the boundary layer physics and air-sea coupling in a simplified environment. This framework is then used to assess the ability of the coupled model to represent the sea surface temperature (SST) diurnal cycle. To this aim, the atmospheric-ocean single column model (AOSCM), called CNRM-CM6-1D, is implemented on a case study derived from the Cindy-Dynamo field campaign over the Indian Ocean, where large diurnal SST variabilities have been well documented.

Comparing the AOSCM and its uncoupled components (atmospheric SCM and oceanic SCM, called OSCM) highlights that the impact of coupling in the atmosphere results both from the possibility to take in to account the diurnal variability of SST, not usually available in forcing products, and from the change in mean state SST as simulated by the OSCM, the ocean mean state not being heavily impacted by the coupling. This suggests that coupling feedbacks are more due to advection processes in the 3D model than to the model physics. Additionally, a sub-daily coupling frequency is needed to represent the SST diurnal variability but the choice of the coupling time-step between 15 min and 3 h does not impact much on the diurnal temperature range simulated. The main drawback of a 3-h coupling being to delay the SST diurnal cycle by 5 h in asynchronous coupled models. Overall, the diurnal SST variability is reasonably well represented in the CNRM-CM6-1 with a 1 h coupling time-step and the upper ocean model resolution of 1 m.

This framework is shown to be a very valuable tool to develop and validate the boundary layer physics and the coupling interface. It highlights the interest to develop other atmosphere-ocean coupling case studies.

Aurore Voldoire et al.

Status: open (until 23 Feb 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CEC1: 'Comment on gmd-2021-413', Juan Antonio Añel, 03 Jan 2022 reply
    • AC1: 'Reply on CEC1', Aurore Voldoire, 03 Jan 2022 reply
      • AC2: 'Reply on AC1', Aurore Voldoire, 03 Jan 2022 reply
        • CEC2: 'Reply on AC2', Juan Antonio Añel, 04 Jan 2022 reply
  • RC1: 'Comment on gmd-2021-413', Anonymous Referee #1, 04 Jan 2022 reply
  • RC2: 'Comment on gmd-2021-413', Anonymous Referee #2, 05 Jan 2022 reply

Aurore Voldoire et al.

Aurore Voldoire et al.

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Short summary
A single column version of the global climate model CNRM-CM6-1 has been designed to ease development and validation of the model physics at the air-sea interface in a simplified environment. This model is then used to assess the ability to represent the sea surface temperature diurnal cycle. We conclude that the sea surface temperature diurnal variability is reasonably well represented in CNRM-CM6-1 with a 1 h coupling time-step and the upper ocean model resolution of 1 m.