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<br />2. No cloud or cell within the experimental unit at the time of initial treatment shall <br />have a top reaching above 10 kilometers (above ground level). <br /> <br />3. At least some of the subject cells shall have top temperatures of -10 oC or colder. <br /> <br />4. At the time of selection, the center of the experimental unit shall be located at least <br />40 kilometers from cumulonimbus clouds displaying radar reflectivities of 50 dBZ or <br />greater in the vicinity. <br /> <br />5. Treatment of cloudS within the experimental unit is to be terminated if: a) more than <br />1 hour has elapsed since the last seeding and if echoes are no longer contained within <br />its boundaries, and/or b) the experimental unit moves beyond 159 kilometers from the <br />radar, and/or c) the monitoring S-band radar has had an operational failure. <br /> <br />Note that a moving or "floating" experimental unit has been chosen for the demonstration <br />project instead of a unit area that is fixed to the ground. This decision is based on the <br />tremendous variability of suitable, Thai, cold convective clouds that might exist in one area <br />on one day and in another area the nexto A fixed-area design would, therefore, not allow for <br />as many seeding opportunities as those provided by a floating area that is tied, not to fixed <br />geography, but to the locations of suitable clouds. <br /> <br />2.8.2 Treatment units <br /> <br />In this design, the treatment units are the convective towers that correspond to the <br />convective cells within the experimental unit and meet the SLWC (supercooled liquid water <br />content) and updraft seeding criteria. The cell receives the treatment, and any effect of <br />seeding should be manifested first in the treatment unit (the cell) and later in the overall <br />experimental unit. <br /> <br />2.8.3 The project study area <br /> <br />Experimental units will be qualified during the cold cloud demonstration project over the <br />area shown on figure 2.1 that is within 159 kilometers of the Omkoi radar in northwest <br />Thailand. The experimental territory excludes all areas in Burma, plus an area of 25- <br />kilometer radius centered on the radar site at Omkoi. This latter region is a "dead zone," in <br />which the radar has difficulty seeing the tops of tall (i.e., > 12 kilometers) echoes during its <br />regular volume scan. <br /> <br />2.8.4 Randomization <br /> <br />i <br />1 <br /> <br />The randomized seeding instructions for the demonstration project will be prepared by <br />statisticians with the AARRP. Care will be taken to avoid long runs of the same treatment <br />decision in preparing the randomizationo <br /> <br />2.8.5 Type of nucleant and means of delivery <br /> <br />The nucleant to be used in this e~periment will be 20-gram AgI flares having the EJ-~W <br />formulation and manufactured by Atmospherics Inc., in Fresno, California, U.S. This flare <br />is complexed with chlorinated hydrophilic material that allows it to nucleate at a faster rate <br />than the modified TB-l formulation that has been used in Texas. According to tests at the <br /> <br />10 <br />