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Show 3. 2. 1. 4 Selected Case Studies The best relationships describing plume behavior , . although far from perfec! have utilized release site wind parameters measured on a one-hundred foot tower. Several individual cases which illustrate significant findings of this series of tests are presented herein. The tests have of necessity been conducted only under VFR flying conditions. 1 Daisy 42 - 22 February 1967: This first case involved a one-cycle per hour release from 8300 ft. Emerald Mountain. The temperature stratification, from a sounding taken at nearby Mt. Harris and shown in Figure 34, indicat neutral conditions to nearly 12, 000 ft. MSL. The wind speeds are moderate and there is fair agreement between the mean release site wind and the uppe level winds. Also, no temperature inversion was indicated below 9500 ft. A by a low level sounding method. Figure 35 is a pictorial illustration of the location of the plume locating tracks fl0wn by aircraft during this test. The majority of the tracks were at 9, 500, 10, 000 and 10, 500 ft. MSL over Thunderbird at a perpendicular distance of 4. 1 n. miles from the release point. Figure 36 is a summary of the ice nuclei counts measured on these tracks, arranged with time as the ordinate. The tracer release periods were from 1125 to 1155 MST and from 1225 to 1255 MST. On tracks 4 through 9, ice nuclei were present at concentrations greater than 50 liter- 1 . On track 13 there was just a hint of an increase in count, and on track 14 high counts we again present. By track 18 the tracer was again completely absent from the high levels. It is significant to note though, that on track 21 at 9, 500 ft. Mi) (some 400 ft. above the highest terrain along the track) some residual mater was present at this low altitude. Figure 3 7 indicates the envelope of peak nuclei count against time. Note thi higher than background nuclei count is first absent between tracks 9 and 10, at about 40 on the time scale. Signal reappeared at 10, 000 ft. MSL between track 13 and track 14 at about 1: 07 on the time scaie. Note that this is 27 minutes after loss of counts - very close to the expected thirty minutes. TI tracer disappears again at 10, 000 ft. MSL between tracks 1 7 and 18 at aboul 35 on the time scale - again very close to the theoretical 30 minutes. The transport times computed for these points are only slightly shorter than tho computed using the release site wind velocities, indicating that the release · site wind gives a good approximation to transport time under these conditioi Again, note the residual material found at a fairly low level on track number 21. Figure 38 is the record of nuclei count measured on the ground at the Rabbit Ears Pass station. Two peaks associated with the two pulses are de! initely present, but with a much shorter clear time between than that indical by the aircraft data. Also, there is a difference in the peak nuclei count measured in the first and second pulses. The first is less by a factor of th the opposite is apparently true in the aircraft data, where the peak concentr 64 . Iii :c |
