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Does the subtropical jet catalyze the mid-latitude atmospheric regimes?

Paolo M. Ruti·Valerio Lucarini·Alessandro Dell'Aquila·Sandro Calmanti·Antonio Speranza
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Abstract

Understanding the atmospheric low-frequency variability is of crucial importance in fields such as climate studies, climate change detection, and extended-range weather forecast. The Northern Hemisphere climate features the planetary waves as a relevant ingredient of the atmospheric variability. Several observations and theoretical arguments seem to support the idea that winter planetary waves indicator obey a non-Gaussian statistics and may present a multimodal probability density function, thus characterizing the low-frequency portion of the climate system. We show that the upper tropospheric jet strength is a critical parameter in determining whether the planetary waves indicator exhibits a uni- or bimodal behavior, and we determine the relevant threshold value of the jet. These results are obtained by considering the data of the NCEP-NCAR and ECMWF reanalyses for the overlapping period. Our results agree with the non-linear orographic theory, which explains the statistical non-normality of the low-frequency variability of the atmosphere and its possible bimodality.

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Paolo M. Ruti, Valerio Lucarini, Alessandro Dell'Aquila, Sandro Calmanti, Antonio Speranza. 2006-04-12. Does the subtropical jet catalyze the mid-latitude atmospheric regimes?. https://doi.org/10.1029/2005gl024620

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