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<br />V. ANALYSIS
<br />
<br />DEGREES TRUE
<br />o
<br />
<br />330
<br />
<br />
<br />va ~
<br />
<br />160
<br />
<br />Figure 45.-700 mb Wind Direction Occurrence for Stonn
<br />Period 1 February to 1 May 1965.
<br />
<br />Conclusion.-Conventional artificial nuclei gen-
<br />erators can be used for Phase II operations. Gen-
<br />erator output should be determined at periodic
<br />intervals, say 1 hour, during nucleation tests if the
<br />calibration equipment is colocated with the nuclei
<br />generator.
<br />Operational Consequence.-It would be desirable
<br />to have a calibration cold box installed on Emerald
<br />Mountain; the instrumentation hut can house the
<br />cold box and protect the operator from the winter
<br />environment during calibration runs.
<br />
<br />Did Artificial Freezing Nuclei
<br />Reach the Target?
<br />
<br />Method.-Assuming the 11,000 foot ASL wind is
<br />between 1800 and 3000 true, precipitation is falling
<br />at Steamboat Springs or the laboratory and the
<br />freezing level is 8,000 feet or lower, release artificial
<br />nuclei for as long as the operational criteria are
<br />satisfied, and tracer material for 1 hour during the
<br />storm. After the storm ceases, collect snow samples
<br />from newfallen snow on the target area and envi-
<br />rons and analyze for Ag concentration-by the
<br />neutron activation analysis technique-and for ZnS
<br />-with the laboratory ZnS analyzer. Determine pro-
<br />files of concentration for each material and compare
<br />with background concentrations to determine in-
<br />tensity of targeting.
<br />
<br />39
<br />
<br />60
<br />
<br />Data.--ZnS and Ag background measurements
<br />from snow samples in the target area. ZnS concen-
<br />trations in snow samples following diffusion tests.
<br />Analysis.- The background concentration of ZnS
<br />in the target area peaked during the Phase I dif-
<br />fusion tests, figure 45, and gradually declined during
<br />the spring thaw. Background values on 7 June are
<br />shown in figure 50 and are with reference to a 1 mv.
<br />(value of 1) noise level in the laboratory analyzer.
<br />The background at all stations approached the noise
<br />level as the thaw was completed. Concentrations
<br />during actual nucleating tests can be expected to
<br />be at least 100 times noise and usually several
<br />hundred to several thousand times noise. The nat-
<br />ural background Ag concentration in the target
<br />area was determined from snow samples taken in
<br />February 19657, table 8. Based on comparisons of
<br />these values with Ag concentrations in snow created
<br />by nucleating supercooled water droplets, the SIN
<br />ratio for actual nucleating tests should be at least 20.
<br />
<br />120
<br />
<br />Table S.-February 1965 Ag Background Concentration in
<br />Target Area.
<br />
<br />Location
<br />
<br />Silver concentration-
<br />pgramsjml. snowmelt
<br />
<br />Fishook Lake, , , , , , , , , ,., , , ' , ' , , , '
<br />Lake Elmo, ' , , , , , ' , , . , , , , , , , , , , ,
<br />Long Lake, , , , , , ' , , , , , , , , , , , , , , , ,
<br />Fish Creek Reservoir, , , , , , , , '
<br />Buffalo Pass, ' , , , , , , , , '
<br />Valley View Lodge,
<br />
<br />26
<br />40
<br />32
<br />41
<br />44
<br />56
<br />
<br />Conclusion.-Ag concentrations throughout the
<br />target area can be determined by a method having
<br />a high inhe'rent SIN ratio; the resulting profiles of
<br />Ag concentration reveal the intensity of targeting
<br />averaged over the storm period. ZnS concentrations
<br />throughout the target area can be determined by
<br />a method having a high inherent S IN ratio; the
<br />resulting profiles of ZnS will cross-check the artificial
<br />nuclei plume dimensions as determined from Ag
<br />concentrations. All tests must be made on samples
<br />that are not contaminated by the existing snowpack
<br />-that is, only on snow from a particular nucleated
<br />storm.
<br />Operational Consequence.-All snow samples
<br />must not be touched during collection to prevent
<br />
<br />7 op, Cit, Schaefer, V, and Fuquay, j., p. 35.
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