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RISOn the Dynamics of Planetary Flow Regimes. Part II: Results from a Hierarchy of Orographically Forced Models
Publisher: American Meteorological Society
Abstract: The relationship between steady states of the large-scale flow regimes revealed by multimodality in phase space and quasi-resonant axes of a linearized atmospheric model (neutral vectors) is investigated by means of a ...
On the Dynamics of Planetary Flow Regimes. Part I: The Role of High-Frequency Transients
Publisher: American Meteorological Society
Abstract: The role of high-frequency transients in the maintenance of planetary-scale flow regimes is investigated using a generalization of the neutral vector approach developed by Marshall and Molteni. Given a nonlinear dynamical ...
Toward a Dynamical Understanding of Planetary-Scale Flow Regimes
Publisher: American Meteorological Society
Abstract: A strategy for diagnosing and interpreting flow regimes that is firmly rooted in dynamical theory is presented and applied to the study of observed and modeled planetary-scale regimes of the wintertime circulation in the ...
The Role of Finite-Time Barotropic Instability during Transition to Blocking
Publisher: American Meteorological Society
Abstract: Linear instability analysis is applied to study the role of barotropic dynamics in the evolution of blocking events during winter 1990/91. Finite-time interval instabilities (i.e., nonnormal-mode structures defined as the ...
Dynamical Extended-Range Prediction of Early Monsoon Rainfall over India
Publisher: American Meteorological Society
Abstract: The 15-member ensembles of 46-day dynamical forecasts starting on each 15 May from 1991 to 2007 have been produced, using the ECMWF Variable Resolution Ensemble Prediction System monthly forecasting system (VarEPS-monthy). ...
Validation of the ECMWF Ensemble Prediction System Using Empirical Orthogonal Functions
Publisher: American Meteorological Society
Abstract: Empirical orthogonal function (EOF) analysis of deviations from the ensemble mean was used to validate the statistical properties of TL159 51-member ensemble forecasts run at the European Centre for Medium-Range Weather ...
A Real-Time Scheme for the Prediction of Forecast Skill
Publisher: American Meteorological Society
Abstract: During the winter of 1988/89, a real-time experimental scheme to predict skill of the ECMWF operational forecast was devised. The scheme was based on statistical relations between skill scores (the predictands) and a number ...
Circulation Regimes and SST Forcing: Results from Large GCM Ensembles
Publisher: American Meteorological Society
Abstract: The purpose of this paper is to study the influence of tropical sea surface temperature (SST) on the midlatitude circulation regime behavior in the Pacific?North American region. Toward this end, a cluster analysis has ...
The EOFs of the Geopotential Eddies at 500 mb in Winter and Their Probability Density Distributions
Publisher: American Meteorological Society
Abstract: In this paper we examine the empirical orthogonal functions (EOFs) of the geopotential eddies at 500 mb in the northern extratropical atmosphere during the cold season, and discuss the time variability of the EOF coefficients ...
Precipitation over Northern Italy: A Description by Means of Principal component Analysis
Publisher: American Meteorological Society
Abstract: Principal component analysis is used to study the rainfall distribution over northern Italy in the cold season (October-April). A spatial analysis is applied to the squares roots of daily data, recorded in 14 months, and ...