Extended Abstract (136K)17B.3
Application of singular vector analyses to tropical cyclone motions
Melinda S. Peng, NRL, Monterey, CA; and C. A. Reynolds
Many tropical cyclone motion and intensity changes are affected by nearby synoptic features. In this study, singular vector (SV) analyses are applied to understand the relationship between tropical cyclone structure and motion, and to examine the influences of the background flows on tropical cyclone movement. Singular vectors represent the fastest growing perturbations to a given trajectory in a linear sense. In this study, the SVs are based on the operational full-physics forecasts from the Navy Operational Global Atmospheric Prediction System (NOGAPS). The SVs are calculated using the Lanczos algorithm applied to the dry forward and adjoint tangent equations of NOGAPS at a T79L30 resolution. A local projection operator is employed to maximize final-time perturbation variances over a region centered near the storm. Recently, NOGAPS has demonstrated satisfactorily its capability of predicting tropical cyclone tracks and SV diagnostics have been successfully applied to extratropical cyclones. This study is focused on two areas. The first is to seek and understand a possible relationship between distributions of initial SV fields in the vicinity of the storm and the subsequent tropical cyclone motion. Preliminary results suggest there are correlations between the initial SV vorticity distribution and the storm motion. The second area of interest is to elucidate the influence of large scale, environmental flow on the storm motion by making SV-based perturbations to the initial analyses and examining the differences to the cyclone tracks in the subsequent forecasts.
Session 17B, Tropical Cyclone Motion
Friday, 7 May 2004, 10:15 AM-11:00 AM, Napoleon I Room
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