The benefits of increasing resolution in global and regional climate simulations for European climate extremes

Iles, Carley E. and Vautard, Robert and Strachan, Jane and Joussaume, Sylie and Eggen, Bernd R. and Hewitt, Chris D. ORCID: https://orcid.org/0000-0002-4718-4009 (2020) The benefits of increasing resolution in global and regional climate simulations for European climate extremes. Geoscientific Model Development, 13 (11). pp. 5583-5607. ISSN 1991-959X

[img]
Preview
Text (Published Version)
gmd-13-5583-2020 (1).pdf
Available under License Creative Commons Attribution 4.0.

Download (4MB) | Preview

Abstract

Many climate extremes, including heatwaves and heavy precipitation events, are projected to worsen under climate change, with important impacts for society. Future projections required for adaptation are often based on climate model simulations. Given finite resources, trade-offs must be made concerning model resolution, ensemble size, and level of model complexity. Here we focus on the resolution component. A given resolution can be achieved over a region using either global climate models (GCMs) or at lower cost using regional climate models (RCMs) that dynamically downscale coarser GCMs. Both approaches to increasing resolution may better capture small-scale processes and features (downscaling effect), but increased GCM resolution may also improve the representation of the large-scale atmospheric circulation (upscaling effect). The size of this upscaling effect is therefore important for deciding modelling strategies. Here we evaluate the benefits of increased model resolution for both global and regional climate models for simulating temperature, precipitation, and wind extremes over Europe at resolutions that could currently be realistically used for coordinated sets of climate projections at the pan-European scale. First we examine the benefits of regional downscaling by comparing EURO-CORDEX simulations at 12.5 and 50 km resolution to their coarser CMIP5 driving simulations. Secondly, we compare global-scale HadGEM3-A simulations at three resolutions (130, 60, and 25 km). Finally, we separate out resolution-dependent differences for HadGEM3-A into downscaling and upscaling components using a circulation analogue technique. Results suggest limited benefits of increased resolution for heatwaves, except in reducing hot biases over mountainous regions. Precipitation extremes are sensitive to resolution, particularly over complex orography, with larger totals and heavier tails of the distribution at higher resolution, particularly in the CORDEX vs. CMIP5 analysis. CMIP5 models underestimate precipitation extremes, whilst CORDEX simulations overestimate compared to E-OBS, particularly at 12.5 km, but results are sensitive to the observational dataset used, with the MESAN reanalysis giving higher totals and heavier tails than E-OBS. Wind extremes are somewhat stronger and heavier tailed at higher resolution, except in coastal regions where large coastal grid boxes spread strong ocean winds further over land. The circulation analogue analysis suggests that differences with resolution for the HadGEM3-A GCM are primarily due to downscaling effects.


Statistics for USQ ePrint 41539
Statistics for this ePrint Item
Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: Current - Institute for Life Sciences and the Environment - Centre for Applied Climate Sciences (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Life Sciences and the Environment - Centre for Applied Climate Sciences (1 Aug 2018 -)
Date Deposited: 17 May 2021 02:00
Last Modified: 31 May 2021 01:22
Uncontrolled Keywords: climate change; global climate models (GCMs); regional climate models (RCMs); climate extremes; Europe
Fields of Research (2008): 04 Earth Sciences > 0401 Atmospheric Sciences > 040104 Climate Change Processes
Fields of Research (2020): 37 EARTH SCIENCES > 3702 Climate change science > 370201 Climate change processes
Identification Number or DOI: https://doi.org/10.5194/gmd-13-5583-2020
URI: http://eprints.usq.edu.au/id/eprint/41539

Actions (login required)

View Item Archive Repository Staff Only