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<br />more protracted analysis of individual types of data, but will <br />provide for real-time learning which has not been available in <br />previous winter orographic weather modification project. Examples <br />of new techniques are: <br /> <br />I. Supercooled Liquid Water Measurement. Up to now, the only <br />reliable and direct measurement of supercooled liquid water has <br />been aircraft instrumentation. However, aircraft can measure only <br />a very small portion of a constantly-changing cloud. To date, <br />efforts to develop a satisfactory rawinsonde-derived index of <br />supercooled liquid water have been unsuccessful. However, the <br />National Oceanic and Atmospheric Administration Wave Propagation <br />Laboratory has developed two new radiometers in the water absorption <br />band which measure this parameter directly. These radiometers <br />provide a quasi-spatial and temporal measurement of this critical <br />parameter. A radiometer is now being tested in the field on the <br />Sierra Cooperative Pilot Project and its data are being compared <br />to direct aircraft measurements. The more sophisticated version <br />will be tested in the Initiation and Preoperational Phases of this <br />project. <br /> <br />2. Measurements of Cloud Temperature and Dimension. Accurate <br />measurements of cloud temperature and dimensions are required. <br />Recently, Ku band radars have been employed successfully to <br />measure cloud tops and bases. These measurements, coupled with <br />rawinsonde observations, will provide excellent estimates of the <br />thermodynamic structure within clouds. Three observation sites <br />will be used so that transbarrier changes in the atmospheric <br />profile can be studied. <br /> <br />. <br /> <br />3. Real-Time AESOP Data. Convergence and divergence at the surface <br />are important indicators of the location of convection initiation <br />and, therefore, where supercooled liquid water is most likely to <br />be found. If a convection climatology shows there is a favored <br />initiation area in foothill regions, ground-based seeding may be <br />feasible. These wind data (as well as precipitation, temperature, <br />and relative humidity) can be now measured and reported with a high <br />density and frequency on a real-time basis. Automatic surface <br />weather stations that relay through geostationary satellites were <br />developed by the Service recently and will be used to obtain these <br />data. <br /> <br />4. Cloud Physics Data. Direct microphysical measurements of cloud <br />particles in both the ice and liquid phases are required to develop <br />a complete understanding of precipitation formation in orographic <br />clouds in the Colorado River Basin. These data must be acquired by <br /> <br />V-4 <br />