Evaluation of Historical CMIP5 GCM Simulation Results Based on Detected Atmospheric Teleconnections

Erzsébet Kristóf,Judit Bartholy,Roland Hollós,Zoltán Barcza,Rita Pongrácz

doi:10.3390/atmos11070723

Erzsébet Kristóf, Judit Bartholy + Show 3 more

Open Access

https://doi.org/10.3390/atmos11070723

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Abstract

Atmospheric teleconnections are characteristic to the climate system and exert major impacts on the global and regional climate. Accurate representation of teleconnections by general circulation models (GCMs) is indispensable given their fundamental role in the large scale circulation patterns. In this study a statistical method is introduced to evaluate historical GCM outputs of the fifth phase of the Coupled Model Intercomparison Project (CMIP5) with respect to teleconnection patterns. The introduced method is based on the calculation of correlations between gridded time series of the 500 hPa geopotential height fields in the Northern Hemisphere. GCMs are quantified by a simple diversity index. Additionally, potential action centers of the teleconnection patterns are identified on which the local polynomial regression model is fitted. Diversity fields and regression curves obtained from the GCMs are compared against the NCEP/NCAR Reanalysis 1 and the ERA-20C reanalysis datasets. The introduced method is objective, reproducible, and reduces the number of arbitrary decisions during the analysis. We conclude that major teleconnection patterns are positioned in the GCMs and in the reanalysis datasets similarly, however, spatial differences in their intensities can be severe in some cases that could hamper the applicability of the GCM results for some regions. Based on the evaluation method, best-performing GCMs can be clearly distinguished. Evaluation of the GCMs based on the introduced method might help the modeling community to choose GCMs that are the most applicable for impact studies and for regional downscaling exercises.

Highlights

Atmospheric teleconnections are persistent, large-scale phenomena that link the variability of meteorological parameters across large geographical distances
Teleconnections can be identified in the Northern Hemisphere (NH) in each examined time period over the North Pacific Ocean, over the North Atlantic Ocean, and in the region of the West
To analyze temporal stability of the teleconnections, a simple diversity index was calculated based on the fields of strongest negative correlations obtained from the Z500 in the Northern Hemisphere’s winter

Summary

Introduction

Atmospheric teleconnections are persistent, large-scale phenomena that link the variability of meteorological parameters across large geographical distances. Teleconnections are studied by the identification of distant geographical areas with co-varying meteorological state variables and are visualized by teleconnection patterns. The most intense regions of the teleconnections are called action centers [1,2,3]. Patterns of the large-scale atmospheric circulation in the Northern Hemisphere (hereinafter referred to as NH) were identified by Wallace and Gutzler [1] by examining teleconnectivity maps. These maps were obtained from the calculation of empirical correlations of gridded geopotential height datasets at the isobaric surface of the 500 hPa field (Z500). Horel [2] applied rotated principal

Results

Discussion

Conclusion