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Click here to Order your Radar Equipment Online WIND SHEAR A major hazard to aviation is the presence of low-level wind shear. Wind shear may result from a variety of phenomena such as synoptic fronts, boundaries associated with thunderstorms, terrain, and nocturnal inversions. Recognition of Wind Shear Wind shear will appear as a discontinuity in the doppler velocity field and is frequently associated with wide spectrum widths. Monitoring changes in the velocity field over time is likely the best approach to recognition of wind shear phenomena. Low-level wind shear can be detected close to the radar in the Mean Radial Velocity product. An indication of extreme shear will show up in a narrow band in the velocity field. This narrow band will likely not be identified in the Velocity Azimuth Display Wind Profile product. However, this product can be useful in keeping track of significant wind speed and direction changes within about 16 nmi of the radar and provide an indication of shear in the vertical.Variations in the spectrum width field are related to the mean wind shear across the radar beam; therefore, a shear layer(s) will usually show up as an enhanced area in the Spectrum Width product. Values of 14 kts, or higher, are usually associated with significant wind shear or turbulence, or both.Considerations The Combined Shear product could be useful for the detection of areas affected by strong wind shear. The product, however, tends to be "noisy" and, in the absence of strong signatures, may be of little use. The product does not take vertical shear into account. For indications of shear in the vertical, the Mean Radial Velocity or Spectrum Width Cross Section products may be useful.CLOUD LAYERS The sensitivity of the WSR-88D provides the user the capability of detecting cloud layers. This information has application to such things as aviation forecasting and forecasting the evolution of precipitation. The WSR-88D can detect large ice crystals that are present in middle and high-level clouds. These reflectivities may range as high as plus 20 dBXe. The Velocity Azimuth Display algorithm will use doppler velocity measurements from middle and high level clouds to generate profiles into the middle atmosphere. These wind profiles allow the operator to monitor the movement of synoptic and smaller scale waves and troughs.This information is now available on CD in Adobe PDF Printable Format |
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