Improved Representation of Extratropical Cyclone Structure in HighResMIP Models. Issue 5 (24th February 2022)

• Record Type: Journal Article
• Authors: Priestley, Matthew D. K.; Catto, Jennifer L.
• Is Part Of: Geophysical research letters. Volume 49:Issue 5(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-24
• Subjects: extratropical cyclone -- composite -- model evaluation -- CMIP6 -- HighResMIP; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL096708
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: General circulation models are broadly able to capture the shape and structure of extratropical cyclones. Increased atmospheric resolution has been shown to improve the representation of cyclone structure. However, the intensity of cyclones, and the strength of their winds, are commonly underestimated in models. Using a cyclone compositing technique applied to the new generation HighResMIP and CMIP6 models, the representation of cyclone wind speeds and airstreams is quantified. CMIP6 models are able to capture the structure of cyclones, however winds associated with various airstreams within the cyclones are too weak. HighResMIP models show considerable improvements, with a majority of cyclone‐scale biases present in the CMIP6 models reduced in both winter and summer seasons in the Northern and Southern hemispheres. HighResMIP and CMIP6 models have similar biases on the large‐scale, with both struggling to represent the width of the upper‐level jet. Plain Language Summary: In order for accurate predictions of the future climate to be made, models must be tested to see if they reproduce features in an accurate way. In this study, we have tested the ability of climate models to represent the intensity and structure of extratropical cyclones. Previously, climate models with a higher resolution have performed better at representing the structure of these cyclones, however most models tend to fail to capture the intensity. Our results demonstrate that models do still struggle to capture the intensity of cyclones, with wind speeds being too weak. However, cyclones simulated by the highest resolution models do a much better job at simulating the intensity of the cyclones, and the strength of the wind speeds within them. In order to study features within extratropical cyclones accurately, high resolution models must be used. Key Points: The strength of cyclone wind speeds are underestimated by CMIP6 models HighResMIP models represent the structure and intensity of cyclones better than CMIP6 models Elements of the large‐scale environment surrounding cyclones are not improved in HighResMIP simulations