Abstract
Some kinematic and dynamic structures of a microburst-producing storm in Colorado were investigated. Dual-Doppler data collected on 14 July, 1982 at 1647 MDT, during the Joint Airport Weather Studies (JAWS) project at Denver's Stapleton International Airport, were objectively analyzed to produce a three-dimensional wind field. The domain of interest had a horizontal dimension of 10 by 10 km centered on the microburst. Vertical velocities were computed by integrating the anelastic continuity equation downward from the storm's top with variational adjustment. Subsequently, fields of deviation perturbation pressure, density, and virtual temperature were retrieved from a detailed wind field using the three momentum equations.
Results show that the microburst being investigated is embedded within a high-reflectivity region associated with heavy precipitation. A strong downflow impinges on the surface producing a stagnation mesohigh inside the microburst. This mesohigh is accompanied by mesolows in the strongest outflow regions, forming a pronounced horizontal perturbation pressure gradient outward from the high-pressure center. The outflow regions extend from the surface to approximately 1 km AGL with maximum divergence in excess of 10 −2 s−1. Inclusion of friction in the pressure equation improves pressure recovery at all levels, especially in the atmospheric boundary layer (ABL). The microburst occurrence in the ABL enhances eddy transfer of momentum. Magnitudes of eddy viscosity and eddy stresses increase as a result of the microburst.
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Lin, YJ., Hughes, R.G. & Pasken, R.W. Subcloud-layer kinematic and dynamic structures of a microburst-producing thunderstorm in Colorado determined from JAWS Dual-Doppler measurements. Boundary-Layer Meteorol 39, 67–86 (1987). https://doi.org/10.1007/BF00121866
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DOI: https://doi.org/10.1007/BF00121866