Northern Hemisphere Extratropical Cyclones in a Warming Climate in the HiGEM High-Resolution Climate Model

Catto, Jennifer L.; Shaffrey, Len; Hodges, Kevin I.

doi:10.1175/2011jcli4181.1

Cited by 115 publications

(119 citation statements)

References 43 publications

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“…2(f)). This error is consistent with the excess cyclones identified in this region in the Hadley Centre models (Greeves et al 2007, Catto et al 2011. Over the Pacific and Atlantic, the shifts in the maximum values of front frequency are associated with both warm fronts and cold fronts ( Fig.…”

Section: Front Frequencysupporting

confidence: 87%

A global evaluation of fronts and precipitation in the ACCESS model

Catto¹,

Jakob²,

Nicholls³

2013

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How global precipitation will change in the future is of great socio-economic importance. It is therefore vital that climate models are able to adequately simulate the characteristics of precipitation and the individual precipitation events. Fronts play an important role in providing precipitation and they can be associated with heavy rain and flooding.In this paper the ACCESS1.3 atmosphere model is evaluated in terms of frontal and non-frontal precipitation. An objective front identification method is applied to data from reanalysis and the model. The fronts are then linked to daily precipitation from observational estimates and the model. The proportion of precipitation associated with fronts and the average intensity of precipitation associated with fronts are then calculated and compared.The frequency of fronts and the proportion of precipitation associated with fronts are well captured by the model. The intensity of precipitation when a front is present is underestimated by the model in most regions, consistent with many previous studies. Decomposing the total precipitation error into components associated with the frequency and intensity of both frontal and non-frontal precipitation shows that the non-frontal precipitation errors contribute the most to the total error, and that there are compensating errors in the model. This regime-and process-based method of model evaluation provides a useful tool to gain deeper understanding into the sources of precipitation errors in climate models.

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Section: Front Frequencysupporting

confidence: 87%

A global evaluation of fronts and precipitation in the ACCESS model

Catto¹,

Jakob²,

Nicholls³

2013

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“…7b. Local maxima in the standard error over Newfoundland, Denmark, Corsica, and near the tip of Greenland appear related to areas of strong primary or secondary cyclogenesis (Hodges et al 2011).…”

Section: ) a Single Grid Pointmentioning

confidence: 94%

“…The analysis methodology is similar to that used in several previous studies of extratropical cyclones (e.g., Bengtsson et al 2006Bengtsson et al , 2009Catto et al 2011;McDonald 2011). Cyclones are identified as maxima in the 850-hPa relative vorticity field and tracked through their life cycle using the method developed by Hodges (1994Hodges ( , 1995Hodges ( , 1999.…”

Section: Example: Storm Tracks In Cmip5mentioning

confidence: 99%

Simple Uncertainty Frameworks for Selecting Weighting Schemes and Interpreting Multimodel Ensemble Climate Change Experiments

et al. 2013

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Future climate change projections are often derived from ensembles of simulations from multiple global circulation models using heuristic weighting schemes. This study provides a more rigorous justification for this by introducing a nested family of three simple analysis of variance frameworks. Statistical frameworks are essential in order to quantify the uncertainty associated with the estimate of the mean climate change response.The most general framework yields the ''one model, one vote'' weighting scheme often used in climate projection. However, a simpler additive framework is found to be preferable when the climate change response is not strongly model dependent. In such situations, the weighted multimodel mean may be interpreted as an estimate of the actual climate response, even in the presence of shared model biases.Statistical significance tests are derived to choose the most appropriate framework for specific multimodel ensemble data. The framework assumptions are explicit and can be checked using simple tests and graphical techniques. The frameworks can be used to test for evidence of nonzero climate response and to construct confidence intervals for the size of the response.The methodology is illustrated by application to North Atlantic storm track data from the Coupled Model Intercomparison Project phase 5 (CMIP5) multimodel ensemble. Despite large variations in the historical storm tracks, the cyclone frequency climate change response is not found to be model dependent over most of the region. This gives high confidence in the response estimates. Statistically significant decreases in cyclone frequency are found on the flanks of the North Atlantic storm track and in the Mediterranean basin.

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“…Bengtsson et al 2009;Catto et al 2010). The 100 extratropical cyclones with lowest minimum SLP per 300 days of simulation are selected (i.e., for the longer simulations with a 5 0.4, 1.0, and 4.0 at T85 resolution, 300 cyclones are analyzed).…”

Section: B Cyclone Identification and Trackingmentioning

confidence: 99%

Extratropical Cyclones in Idealized Simulations of Changed Climates

2015

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Cyclones are a key element of extratropical weather and frequently lead to extreme events like wind storms and heavy precipitation. Understanding potential changes of cyclone frequency and intensity is thus essential for a proper assessment of climate change impacts. Here the behavior of extratropical cyclones under strongly varying climate conditions is investigated using idealized climate model simulations in an aquaplanet setup. A cyclone tracking algorithm is applied to assess various statistics of cyclone properties such as intensity, size, lifetime, displacement velocity, and deepening rates. In addition, a composite analysis of intense cyclones is performed. In general, the structure of extratropical cyclones in the idealized simulations is very robust, and changes in major cyclone characteristics are relatively small. Median cyclone intensity, measured in terms of minimum sea level pressure and lower-tropospheric relative vorticity, has a maximum in simulations with global mean temperature slightly warmer than present-day Earth, broadly consistent with the behavior of the eddy kinetic energy analyzed in previous studies. Maximum deepening rates along cyclone tracks behave similarly and are in agreement with linear quasigeostrophic growth rates if the effect of latent heat release on the stratification is taken into account. In contrast to moderate cyclones, the relative vorticity of intense cyclones continues to increase with warming to substantially higher temperatures, and this is associated with enhanced lower-tropospheric potential vorticity anomalies likely caused by increased diabatic heating. Moist processes may, therefore, lead to the further strengthening of intense cyclones in warmer climates even if cyclones weaken on average.

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Northern Hemisphere Extratropical Cyclones in a Warming Climate in the HiGEM High-Resolution Climate Model

Cited by 115 publications

References 43 publications

A global evaluation of fronts and precipitation in the ACCESS model

A global evaluation of fronts and precipitation in the ACCESS model

Simple Uncertainty Frameworks for Selecting Weighting Schemes and Interpreting Multimodel Ensemble Climate Change Experiments

Extratropical Cyclones in Idealized Simulations of Changed Climates

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