A wavelet-based approach to detect climate change on the coherent and turbulent component of the atmospheric circulation

Davide Faranda (1, 2) , Dimitri Defrance (1)

1 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
2 ESTIMR - Extrèmes : Statistiques, Impacts et Régionalisation

The modifications of atmospheric circulation induced by anthropogenic effects are difficult to capture because wind fields feature a complex spectrum where the signal of large-scale coherent structures (planetary, baroclinic waves and other long-term oscillations) is mixed up with turbulence. Our purpose is to study the effects of climate changes on these two components separately by applying a wavelet analysis to the 700 hPa wind fields obtained in climate simulations for different forcing scenarios. We study the coherent component of the signal via a correlation analysis to detect the persistence of large-scale or long-lasting structures, whereas we use the theory of autoregressive moving-average stochastic processes to measure the spectral complexity of the turbulent component. Under strong anthropogenic forcing, we detect a significant climate change signal. The analysis suggests that coherent structures will play a dominant role in future climate, whereas turbulent spectra will approach a classical Kolmogorov behaviour.

Domains: Ocean, Atmosphere; Climatology

Davide Faranda, Dimitri Defrance. A wavelet-based approach to detect climate change on the coherent and turbulent component of the atmospheric circulation. Earth System Dynamics, 2016, 7, pp.517 - 523. ⟨10.5194/esd-7-517-2016⟩. ⟨cea-01493854⟩