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RISImpact of Transient Error Growth on Global Average Predictability Measures
Publisher: American Meteorological Society
Abstract: The divergence of initially close trajectories sets the limit of dynamical predictability for infinitesimally small errors; its global average measure is given by the first Liapunov exponent. It is shown, within the framework ...
Statistical Properties of Predictability from Atmospheric Analogs and the Existence of Multiple Flow Regimes
Publisher: American Meteorological Society
Abstract: The problem of predictability in relation to the existence of multiple flow regimes is examined for the atmosphere on the basis of observations. The existence of multiple-flow regimes and the dynamics of transitions between ...
Numerical Experiments on the Influence of Orography on Cyclone Formation with an Isentropic Primitive Equation Model
Publisher: American Meteorological Society
Abstract: Numerical integration experiments with a primitive equation model in isentropic coordinates are performed to investigate the influence of orography on cyclone formation. Results obtained in the presence of an isolated ...
Restrictions and Alternative Formulation of the Quasi-Geostrophic Barotropic Channel Model
Publisher: American Meteorological Society
Abstract: We derive for a channel model a meridional boundary condition that is equivalent to Phillip's one, but is simpler to implement. We then show that the presence of Ekman dissipation in a quasi-geostrophic channel model with ...
Assimilation of Standard and Targeted Observations within the Unstable Subspace of the Observation–Analysis–Forecast Cycle System
Publisher: American Meteorological Society
Abstract: In this paper it is shown that the flow-dependent instabilities that develop within an observation?analysis?forecast (OAF) cycle and that are responsible for the background error can be exploited in a very simple way to ...
Clinogenesis and Frontogenesis in Jet-Stream Waves. Part II: Channel Model Numerical Experiments
Publisher: American Meteorological Society
Abstract: Frontogenesis (FG) is examined in a ?channel model? based on a primitive-equation isentropic formulation by Eliassen and Raustein. Meridional temperature gradients, static stability and a tropopause are specified to give ...
Clinogenesis and Frontogenesis in Jet-Stream Waves. Part I: Analytical Relations to Wave Structure
Publisher: American Meteorological Society
Abstract: The circulations that alter the baroclinic structure along wave-shaped currents are investigated for gradient and nongradient flow. In the case of deformations which result in an increase of baroclinity and vertical shear ...
On Lorenz's Law for the Growth of Large and Small Errors in the Atmosphere
Publisher: American Meteorological Society
Abstract: Lorenz's hypothesis of a quadratic law governing the growth of errors provides an estimate of small error growth in the atmosphere based on the knowledge of large error behavior. An atmospheric model whose simplicity allows ...
Numerical Experiments on Orographic Cyclogenesis: Relationship Between the Development of the Lee Cyclone and the Basic Flow Characteristics
Publisher: American Meteorological Society
Abstract: Idealized numerical experiments are performed using a channel version of the HIBU (Mesinger?Janji?) primitive equation model to reproduce cyclogenesis in the lee of a mountain chain resembling the Alps. Cyclones of differing ...
Internal Frontogenesis: A Two-Dimensional Model in Isentropic, Semi-Geostrophic Coordinates
Publisher: American Meteorological Society
Abstract: A two-dimensional semi-geostrophic model in isentropic coordinates is applied to the study of internal frontogenesis induced by a geostrophic deformation field. A continuous potential vorticity distribution is considered ...