TITLE

Targeting Studies for the Extratropical Transition of Hurricane Fabian: Signal Propagation, the Interaction between Fabian and Midlatitude Flow, and an Observation Strategy

AUTHOR(S)
Hua Chen; Weiyu Pan
PUB. DATE
August 2010
SOURCE
Monthly Weather Review;Aug2010, Vol. 138 Issue 8, p3224
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
This study examines how the impact of targeted observations propagates during the extratropical transition (ET) of Hurricane Fabian. Signal (i.e., the forecast difference between denial experiments and the control experiment) propagation can reveal the interaction between the tropical cyclone (TC) and the midlatitude jet, and the energy dispersion or propagation of the TC undergoing ET also can be determined. The crucial role of an upper-level trough is discussed. Based on this study, a strategy issue regarding targeted observations of ET and several typical problems regarding the numerical prediction of ET are discussed. The results show that the greatest signals along with their propagation are associated closely with various types of instabilities. In general, the signal first appears at the location of the TC, and then it propagates to the midlatitude jet through the interaction between the TC and the jet itself. Thereafter, signals propagate downstream along the jet and downward to the lower troposphere at the same time by way of Rossby wave packets; the jet essentially acts as a waveguide. Through the signal propagation and development in the jet, the impact of targeted observations seems sensitive to the ET process. The interaction between the TC and the jet occurs as high θ (low potential vorticity) air flows out of the TC toward the northeast and into the jet below the tropopause. The interaction may be strengthened by an upstream trough at upper levels. The TC outflow enhances the potential vorticity (PV) gradient and baroclinity in the jet. Therefore, the jet becomes stronger and more baroclinically unstable. The signal propagation also indicates the energy dispersion of a TC undergoing ET. The strong southwesterly flow ahead of the upper-level trough steers Fabian to higher latitudes, and strengthens the advection process of low PV air into the jet. Therefore, the development of the upper-level trough and its proximity to the TC are crucial for the interaction between the TC and the jet, and the resulting signal propagation. Small deviations from this synoptic situation may result in great differences in the signal propagation and the ET forecast. The most suitable region for targeting is likely a region where crucial synoptic processes can magnify initial errors.
ACCESSION #
53561210

 

Related Articles

  • Nonlinear interaction of small-scale Rossby waves with an intense large-scale zonal flow. Manin, Dmitrii Yu.; Nazarenko, Sergey V. // Physics of Fluids;Mar1994, Vol. 6 Issue 3, p1158 

    The system of Rossby waves is unstable with respect to modulations. This instability results in the generation of a large-scale zonal flow with zero mean vorticity. It is shown that in both stable and unstable situations, a finite-time singularity formation takes place in the system. Such a...

  • Centrifugal-Dissipative Instability of Rossby Vortices and Their Cyclonic–Anticyclonic Asymmetry. Chefranov, S. G. // JETP Letters;3/25/2001, Vol. 73 Issue 6, p274 

    A new linear centrifugal-dissipative mechanism is proposed that explains the vortex asymmetry observed, in particular, in the structure of low-frequency anticyclonic Rossby vortices. It is shown that the relevant centrifugal-dissipative instability, which spontaneously breaks the chiral symmetry...

  • Tropical Cyclogenesis in the Western North Pacific as Revealed by the 2008-09 YOTC Data*. Xu, Yamei; Li, Tim; Peng, Melinda // Weather & Forecasting;Aug2013, Vol. 28 Issue 4, p1038 

    The Year of Tropical Convection (YOTC) high-resolution global reanalysis dataset was analyzed to reveal precursor synoptic-scale disturbances related to tropical cyclone (TC) genesis in the western North Pacific (WNP) during the 2008-09 typhoon seasons. A time filtering is applied to the data to...

  • Rossby solitary vortices, on giant planets and in the laboratory. Nezlin, Mikhail V. // Chaos;Jun94, Vol. 4 Issue 2, p187 

    Presents a review of laboratory experiments with a layer of shallow water having a free surface and rotating together with a vessel of parabolic form. Generation of large-scale Rossby vortex chains; Laboratory model for the Great Red Spot of Jupiter; Object of nonlinear physics; Comparison of...

  • Wavenumber-2 and Wavenumber-m Vortex Rossby Wave Instabilities in a Generalized Three-Region Model. Terwey, Wesley D.; Montgomery, Michael T. // Journal of the Atmospheric Sciences;8/15/2002, Vol. 59 Issue 16, p2421 

    A recent study using a discrete three-region nondivergent approximation for the inner-core region of a mature hurricane-like vortex fails to catch wavenumber-2 azimuthal shear instabilities that are observed in experiments and predicted by similar continuous model representations. With hurricane...

  • Finite-amplitude topographic Rossby waves in a channel. Clarke, S.R.; Johnson, E.R. // Physics of Fluids;Jan1999, Vol. 11 Issue 1, p107 

    Describes Rossby waves propagating along a channel with a discontinuity in potential vorticity. Derivation of a finite-amplitude, long-wave equation giving the displacement of the material interface separating two constant vorticity regions; Solution for both steady and unsteady...

  • Nonlinear Balance in Terrain-Following Coordinates. Decker, Steven G. // Monthly Weather Review;Feb2010, Vol. 138 Issue 2, p605 

    Potential vorticity (PV) is a powerful concept in geophysical fluid dynamics. One property of PV that makes it so powerful is that it may be inverted under certain conditions, one of which is the imposition of a balance constraint. Previous studies have made use of a particular nonlinear balance...

  • Potential Vorticity Anomalies of the Lowermost Stratosphere: A 10-Yr Winter Climatology. Kew, Sarah F.; Sprenger, Michael; Davies, Huw C. // Monthly Weather Review;Apr2010, Vol. 138 Issue 4, p1234 

    Inspection of the potential vorticity (PV) distribution on isentropic surfaces in the lowermost stratosphere reveals the ubiquitous presence of numerous subsynoptic positive PV anomalies. To examine the space–time characteristics of these anomalies, a combined “identification and...

  • The Effect of Tropospheric Jet Latitude on Coupling between the Stratospheric Polar Vortex and the Troposphere. Garfinkel, Chaim I.; Waugh, Darryn W.; Gerber, Edwin P. // Journal of Climate;Mar2013, Vol. 26 Issue 6, p2077 

    A dry general circulation model is used to investigate how coupling between the stratospheric polar vortex and the extratropical tropospheric circulation depends on the latitude of the tropospheric jet. The tropospheric response to an identical stratospheric vortex configuration is shown to be...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics