Preprints
https://doi.org/10.5194/wcd-2021-51
https://doi.org/10.5194/wcd-2021-51

  30 Jul 2021

30 Jul 2021

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

Orographic resolution driving the improvements associated with horizontal resolution increase in the Northern Hemisphere winter mid-latitudes

Paolo Davini1, Federico Fabiano2, and Irina Sandu3 Paolo Davini et al.
  • 1Consiglio Nazionale delle Ricerche, Istituto di Scienze dell’Atmosfera e del Clima (CNR-ISAC), Torino, Italy
  • 2Consiglio Nazionale delle Ricerche, Istituto di Scienze dell’Atmosfera e del Clima (CNR-ISAC), Bologna, Italy
  • 3European Centre for Medium-Range Weather Forecasts (ECWMF), Reading, UK

Abstract. In recent years much attention has been devoted to the investigation of the impact of increasing the horizontal resolution of global climate models. In the present work, a set of atmosphere-only idealized sensitivity simulations with EC-Earth3 have been designed to disentangle the relative roles of increasing the resolution of the resolved orography and of the atmospheric grid. Focusing on the winter Northern Hemisphere, it is shown that if the grid is refined while keeping the resolved orography unchanged, model biases are reduced only in some specific occasions. Conversely, increasing the resolved (or mean) orography is found to clearly reduce several important systematic model errors, including synoptic transient eddies, the North Atlantic jet stream variability and atmospheric blocking frequency and duration. From an analysis of the radiation budget it is concluded that the large changes in radiative fluxes caused by the resolution increase – something commonly observed in climate models – have a relevant impact on the atmospheric circulation, partially offsetting the benefits obtained from the increase in orographic resolution. These findings point to the necessity of always tuning climate models to fully exploit the benefits of high horizontal resolution.

Paolo Davini et al.

Status: open (until 16 Oct 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on wcd-2021-51', Anonymous Referee #1, 14 Sep 2021 reply

Paolo Davini et al.

Paolo Davini et al.

Viewed

Total article views: 245 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
177 61 7 245 3 0
  • HTML: 177
  • PDF: 61
  • XML: 7
  • Total: 245
  • BibTeX: 3
  • EndNote: 0
Views and downloads (calculated since 30 Jul 2021)
Cumulative views and downloads (calculated since 30 Jul 2021)

Viewed (geographical distribution)

Total article views: 241 (including HTML, PDF, and XML) Thereof 241 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 17 Sep 2021
Download
Short summary
In climate models, improvements obtained in the winter mid-latitude circulation following horizontal resolution increase are mainly caused by the more detailed representation of the mean orography. A high resolution climate model with a low resolution orography might underperform a low resolution model with a low resolution orography. The absence of proper model tuning at high resolution is considered as the potential reason behind such lack of improvements.