radiates energy in the same microwave region of theelectromagnetic spectrum that is used by the WSR-88D.RECOGNITION OF SOLAR EFFECTS.— Theseechoes may be expected to appear as continuousreturns, in a narrow “baseball bat” shape, out one ortwo radials at the solar attitude. Reflectivity valuesgenerally range between 10 and 20 dBZe. See figure12-5. Solar effects will appear for one or two volumescans at a single elevation of the Reflectivity, MeanRadial Velocity, or Spectrum Width product and up to30 min on a Composite Reflectivity product.ASSESSING IMPACTS OF SOLAREFFECTS.— In the absence of other echoes, typicalreflectivity values from solar effects are from near zerodBZe in close to the radar, to 20 dBZe or higher at 250nmi. The apparent reduction in the sun’s signal nearerthe radar is due to the range normalization correctionapplied to reflectivity. The velocity and spectrum widthfields indicate range-aliased data out to the maximumrange of these products, that is, 124 nmi. OtherReflectivity-derived products that will show thiscontamination are the Echo Tops, CompositeReflectivity, and Layer Composite Reflectivity. TheStorm Series algorithms will generally not be affectedsince the reflectivity values are below the thresholdsused to detect storms.Velocity-derived products that will be contaminatedare the Storm Relative Mean Radial Velocity Map, andRegion. At longer ranges, the contaminated radial maydisrupt pattern vectors used to identify circulations inthe mesocyclone algorithm, where the sun’s signal isstronger than the corresponding storm echo. At close-inranges, the sun’s signal is too weak to impact theTornadic Vortex Signature algorithm.The solar effects can also cause erroneous outputand increase edit time of the radar-coded message inthese areas.INTERPRETATION OF DOPPLERVELOCITY PATTERNSAlthough a single doppler radar observes only thecomponent of the wind in a radial direction from theFigure 12-5.-Streaks of low reflectivity extending outward for two radials to the northeast of the radarcaused by solar effects.12-8
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