Abstract: The low-frequency variability in the midlatitudes is described through an analysis of the oscillatory phenomena. In order to isolate nearly periodic components of the atmospheric flow, the multichannel version of the ...

Abstract: The theory of empirical normal modes (ENMs) for a shallow water fluid is developed. ENMs are basis functions that both have the statistical properties of empirical orthogonal functions (EOFs) and the dynamical properties ...

Abstract: We present a new statistical-dynamical approach to the concept of weather regimes, including the effect of tralisients, without any assumption other than scale separation. The method is applied to a quasi-geostrophic channel ...

Abstract: A low-order deterministic qualitative model is formulated in order to simulate extratropical low-frequency variability. This deterministic model is based on a filtering of the potential vorticity equation on the 315-K ...

Abstract: The forcing of low-frequency variability by synoptic transient traveling perturbations is investigated within a quasi-geostrophic channel forced by a localized baroclinic jet. Spontaneously generated baroclinic perturbations ...

Abstract: Low-frequency variability of large-scale atmospheric dynamics can be represented schematically by a Markov chain of multiple flow regimes. This Markov chain contains useful information for the long-range forecaster, provided ...

Abstract: Two different definitions of midlatitude weather regimes are compared. The first seeks recurrent atmospheric patterns. The second seeks quasi-stationary patterns, whose average tendency vanishes. Recurrent patterns are ...

Abstract: The long-term predictability of 70-kPa geopotential heights is examined by a series of hindcast experiments over a validation period of 40 years using empirical models. Only the North Atlantic sector is considered. Significant ...

Abstract: The statistical model proposed by Vautard et al. is applied to the seasonal prediction of surface air temperatures over North America (Canada and the United States). This model is based on sea surface temperature predictors ...