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Show The first line was picked up while spiralling downwind of the release at 1520 MST and 1524 MST, and the signal is plotted in A and B on Figure 61. At these locations six miles downwind, the initially zero width line source has spread in width to about 1. 3 n. mi. The timing agrees well with the projectei location of the first pulse. The first line was detected at C on an outbound rr track at about 13 nautical miles from the release point, and the width had in- [ creased slightly to 1. 7 nautical miles. On the inbound track the line was de- 1 tected at D and the width was 1. 9 nautical miles. No evidence of the second .line was found except for a very slight indication in plot D at s ·e ven miles. This agrees with the expected separation of 4 miles and the projected location, but it is not clear why a more definite indication of the second line was not found on this inbound track. The burn time on the second line was not as lon~ as the first and the whole line was therefore further to the south. On a long outbound track at E and F there is definite evidence of two distinct peaks. They are separated by only two nautical miles instead of the expected four. Based on this small separation and the projected location, it is believe! that both peaks are associated with the first line. At 3 miles in plot D a doubl peak is starting to appear. At E and F, at 2 2 nautical miles, the width has increased to 4. 5 nautical miles. The aircraft evidently went too far north to pick up the second line; then on the return track, which was south of the first line, the second line was intercepted at G where the plume width at about 22 nautical miles was 7. 8 nautical miles. ' ' ~lST ized rele mirn secl Fi~ The peak concentration measured at C and D ( 14 n. mi. ) is an order of magni· ~asi tude greater than that at E, F and G (22 n. mi. ). The increased lateral sprei that is not enough to account for the decrease in concentration. This indicates thal either: 1) convective scale mixing over the continental divide caused increasi vertical dispersion, or 2) general uplift of the plume axis by the ridge caused the tracks to be in the lower portion of the plume at this distance. Tetroon flights in the area have shown that with near neutral lapse rates, maximum lift occurs over the maximum rate of increase in terrain elevation. This wou lend credence to the hypothesis that sampling was being done below the plume level of maximum concentration. On the other hand, some small cumulus clouds were observed over the divide during the test so convective mixing coul also have been important. If it is assumed that plume width at the altitude of maximum concentration is the Fi~ (as seri ure two oft: Thl a, the comparisons between predicted plume widths for neutral stratificatior ThE The predicted plume widths based on a standard diffusion model agree fairly well with the observed widths for this aircraft release. not 4 and observed plume widths are shown in Table 8. On 31 March 1969, a test of two line source releases was conducted. The W profile and temperature stratification measured at Mt. Harris at 1222 and !Ji 100 rel1 1ni1 Pr( |