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. Copyright 2006 by the American Geophysical Union.
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)
Ruti, P. M., Lucarini, V., Dell'Aquila, A., Calmanti, S., & Speranza, A. (2006). Does the subtropical jet catalyze the midlatitude atmospheric regimes? Geophysical Research Letters, 33(6), -. [L06814]. https://doi.org/10.1029/2005GL024620