S-Band Dual-Polarization Radar Observations of Winter Storms

This study is based on analyses of dual-polarization radar observations made by the 11-cm-wavelength Colorado State University–University of Chicago–Illinois State Water Survey (CSU–CHILL) system during four significant winter storms in northeastern Colorado. It was found that values of specific dif...

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Bibliographic Details
Published in:	Journal of applied meteorology and climatology 2011-04, Vol.50 (4), p.844-858
Main Authors:	Kennedy, Patrick C., Rutledge, Steven A.
Format:	Article
Language:	eng
Subjects:	Aggregates Atmospheric sciences Atoms & subatomic particles Bulk density Cold Crystals Dual polarization radar Earth, ocean, space Exact sciences and technology External geophysics Ice Ice particles Meteorology Microwave scattering Particle density Polarization Precipitation Propagation Radar Radar echoes Radar tracking Reflectance Snow Snowfall Storms Temperature Temperature regime Wavelength Winter Winter storms
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Summary:	This study is based on analyses of dual-polarization radar observations made by the 11-cm-wavelength Colorado State University–University of Chicago–Illinois State Water Survey (CSU–CHILL) system during four significant winter storms in northeastern Colorado. It was found that values of specific differential phaseK DPoften reached local maxima of ∼0.15°–0.4° km−1in an elevated layer near the −15°C environmental temperature isotherm. The passage of these elevated positiveK DPareas is shown to be linked to increased surface precipitation rates. Calculations using a microwave scattering model indicate that populations of highly oblate ice particles with moderate bulk densities and diameters in the ∼0.8–1.2-mm range can generateK DP(and differential reflectivityZ DR) values that are consistent with the radar observations. The persistent correlation between the enhancedK DPlevel and the −15°C temperature regime suggests that rapidly growing dendrites likely played a significant role in the production of the observedK DPpatterns. The detection of organized regions of S-bandK DPvalues greater than ∼0.1°–0.2° km−1in winter storms may therefore be useful in identifying regions of active dendritic particle growth, as a precursor to aggregate snowfall.
ISSN:	1558-8424 1558-8432