Extended Abstract (160K)P3.4
A new direction in clear-air turbulence forecasting based on spontaneous imbalance, Part I: Application of theory
John A. Knox, Univ. of Georgia, Athens, GA; and D. W. McCann and P. D. Williams
We present a new method of clear-air turbulence (CAT) forecasting based on the Lighthill-Ford theory of spontaneous imbalance and emission of inertia-gravity waves. A scale analysis of this theory for mid-latitude synoptic-scale flows identifies advection of relative vorticity as the leading-order source term. Second-order terms including the Jacobian, divergence-vorticity product, and cross-product of velocity with the gradient of divergence may also play non-negligible roles for situations in which Ro < 1 but not Ro << 1. Examination of these leading- and second-order terms appears to help explain the utility of previous, more empirically inspired CAT forecast diagnostics. We then combine the Lighthill-Ford theory with the TKE approach of McCann to create a dynamically consistent, easily implemented and operationally superior CAT forecasting approach.
Poster Session 3, Turbulence, Volcanic Ash, and Instrumentation Posters
Wednesday, 23 January 2008, 2:30 PM-4:00 PM, Exhibit Hall B
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