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<br />(Items 1 and @ are computed from VAD scans at 700 elevation.) <br /> <br />o Time laps,e photographs (PPI, RHI) of reflectivity and velocity <br /> <br />o Power spectra of vertical velocities. <br /> <br />5. Polarization Lidar Technology and Meteorology <br /> <br />Key measurement capabilities of the University of Utah lidar are: <br /> <br />o Location (and temperature from sounding) of supercooled water; <br /> <br />o Precipitation mechanisms - aggregation versus riming. <br /> <br />Maximum information content is derived from combined remote sensing <br />observations (K-band radar, lidar, radiometer). <br /> <br />Summary of findings to date: <br /> <br />o Radiometric liquid water values follow lidar observations of liquid <br />cloud base height, but lidar is monO! sensitive to thin (and cold) <br />water layers. <br /> <br />o Liquid layers tend to reside in areas with relatively low radar <br />reflectiv:Lties (--0 to -10 dBZ). <br /> <br />o At Beaver:, liquid cloud bases are b:imodally distributed, with a peak <br />at ~3 km MSL (cumulus and stratus clouds at the barrier crest <br />height), and at ~.5 km MSL (generally pre-frontal altocumulus). <br /> <br />o Radiometric LW values increase with increasing cloud base temper- <br />ature and decreasing radar reflectivity factors. <br /> <br />o Some liquid water is almost always detected during storms. <br /> <br />6. Past and Present Analyses of Cloud Physi4::s and Seeding Opportunities <br /> <br />An analysis of a shallow orographic cloud system with emergent convection <br />was presented. This cloud system developed on 27-28 February 1983 over the <br />Tushar Mountains. Radiometric data was used to show that this cloud had high <br />liquid water contents for nearly twelve hours.. During this period, precipi- <br />tation was minimal. Aircraft measurements during the later part of the period <br />confirmed that high liquid water contents werE! present. Ice particle concen- <br />trations were less than 5 liter-1 Based on high liquid water contents, low <br />precipitation rate, and low ice patticle concEmtrations, CSU investigators <br />concluded that this cloud system had a high modification potential. A clima- <br />tology of shallow clouds was presented from the 1983 season based on radar <br />determined cloud top data. Although this climatology was preliminary, it <br />suggested that such cloud systems may have beE!n present during a significant <br />part of the 1983 field season. The preliminary conclusion was that these <br />clouds may have a significant potential for precipitation augmentation. <br /> <br />43 <br />