Open AccessUnderstanding Midlatitude Jet Variability and Change Using Rossby Wave Chromatography: Methodology
Author(s) -
David J. Lorenz
Publication year - 2015
Publication title -
journal of the atmospheric sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.853
H-Index - 173
eISSN - 1520-0469
pISSN - 0022-4928
DOI - 10.1175/jas-d-13-0199.1
Subject(s) - baroclinity , rossby wave , middle latitudes , eddy , atmospheric sciences , rossby radius of deformation , barotropic fluid , geology , zonal flow (plasma) , mean flow , troposphere , forcing (mathematics) , momentum (technical analysis) , jet (fluid) , climatology , geophysics , physics , meteorology , mechanics , turbulence , plasma , finance , quantum mechanics , economics , tokamak
Rossby wave chromatography (RWC) is implemented in a linearized barotropic model as a tool to diagnose and understand the interaction between the midlatitude jet and the eddies. Given the background zonal-mean flow and the space–time structure of the baroclinic wave activity source, RWC calculates the space–time structure of the upper-tropospheric eddy momentum fluxes. Using the convergence of the vertical Eliassen–Palm (E–P) flux in the upper troposphere as the wave source, RWC reproduces the main features of a GCM’s mean state and response to external forcing. When coupled to the zonal-mean zonal wind and a simple model of wave activity source phase speed changes, RWC also simulates the temporal evolution of the GCM’s internally generated zonal-mean zonal wind anomalies. Because the full space–time structure of the baroclinic wave activity source is decoupled from the background flow, RWC can be used to isolate and quantify the dynamical mechanisms responsible for 1) the poleward shift of the midlatitude jet and 2) the feedbacks between the eddy momentum fluxes and the background flow in general.