The Ability of CMIP5 Models to Simulate North Atlantic Extratropical Cyclones

The ability of the climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) to simulate North Atlantic extratropical cyclones in winter [December–February (DJF)] and summer [June–August (JJA)] is investigated in detail. Cyclones are identified as maxima in T42 vor...

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Bibliographic Details
Published in:Journal of climate 2013-08, Vol.26 (15), p.5379-5396
Main Authors: Zappa, Giuseppe, Shaffrey, Len C., Hodges, Kevin I.
Format: Article
Language:English
Subjects:
Algorithms
Atmospheric models
Atmospherics
Bias
Climate change
Climate models
Cyclones
Datasets
Earth, ocean, space
Exact sciences and technology
External geophysics
Extratropical cyclones
Geophysics. Techniques, methods, instrumentation and models
Global climate models
Greenhouse gases
Intercomparison
Kinematics
Mean sea level
Meteorology
Modeling
Modelling
Northern Hemisphere
Precipitation
Representations
Sea level
Sea level pressure
Simulation
Simulations
Storm tracks
Storms
Storms, hurricanes, tornadoes, thunderstorms
Studies
Tracking
Vorticity
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Summary:The ability of the climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) to simulate North Atlantic extratropical cyclones in winter [December–February (DJF)] and summer [June–August (JJA)] is investigated in detail. Cyclones are identified as maxima in T42 vorticity at 850 hPa and their propagation is tracked using an objective feature-tracking algorithm. By comparing the historical CMIP5 simulations (1976–2005) and the ECMWF Interim Re-Analysis (ERA-Interim; 1979–2008), the authors find that systematic biases affect the number and intensity of North Atlantic cyclones in CMIP5 models. In DJF, the North Atlantic storm track tends to be either too zonal or displaced southward, thus leading to too few and weak cyclones over the Norwegian Sea and too many cyclones in central Europe. In JJA, the position of the North Atlantic storm track is generally well captured but some CMIP5 models underestimate the total number of cyclones. The dynamical intensity of cyclones, as measured by either T42 vorticity at 850 hPa or mean sea level pressure, is too weak in both DJF and JJA. The intensity bias has a hemispheric character, and it cannot be simply attributed to the representation of the North Atlantic large-scale atmospheric state. Despite these biases, the representation of Northern Hemisphere (NH) storm tracks has improved since CMIP3 and some CMIP5 models are able of representing well both the number and the intensity of North Atlantic cyclones. In particular, some of the higher-atmospheric-resolution models tend to have a better representation of the tilt of the North Atlantic stormtrack and of the intensity of cyclones in DJF.
ISSN:0894-8755
1520-0442
DOI:10.1175/jcli-d-12-00501.1