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SEPTEMBER 1996 REYNOLDS 1447 SLW 0.8 .S .06 0.6E E a.. .04 O.4i u a.. .02 0.2~ 0 0.0 a: 300 16 ~ i5 240 12 .s I- - U) U) 180 8 :J :J C} <!J 120 4 .:.: a.. 60 0 c:; 16 ~ ~300 12 .s e:; 240 a.. 0 8 en o 180 4 a.. ~ ~ 120 0 0- -2 80 ~ e- T 60 I I- .4 a: 40 -6 20 DB 12 16 20 00 04 08 TIME (UTe) FIG. 16. Various parameters observed at the Jackson Creek Observatory for 17 February 1993. Parameters from top to bottom are precipitation (bar) and cloud-integrated liquid water from a radiometer (dotted line), peak gust direction (dotted line) and speed, average wind direction (dotted line) and speed, relative humidity (heavy), and temperature. Radiometer data are de- leted when contaminated by melting precipitation. Temperature and wind data are missing after 0000 UTe. altitudes comparable to release altitudes. It was very easy to distinguish between plumes along the valley track, as they were quite distinct. Excellent documen- tation of SF6 plumes over the valley from both sites were provided on 9 March. Six passes noted plumes from site 7, and seven passes noted plumes from site 9. Five passes noted plumes from both sites. Pass 8 on this day is shown in Fig. 11. It is typical of the averages computed from all plume intersections on this day. For site 7, the average plume width was 3.4 kIn. The av- erage plume concentration was 87 ppt at an elevation of 2261 m. For site 9 the average plume width was 5.5 kIn with an average SF6 concentration of 52 ppt at an elevation of 2326 m. Note that the plume from site 7 was detected at and below 2367 m, while the plume from site 9 was detected to 2484 m. For 19 March, a day in which strong turbulence was observed, six plumes were intersected from site 7 and 4 from site 9. Average plume dimensions for site 7 were 3 kIn, with an average SF6 concentration of 30 ppt. For site 9 the respective values were 2.4 kIn and 18 ppt. The average plume elevation was 2350 m for both sites. In this case the site 7 plume was transported to higher elevations than occurred for those from site 9. Plume characteristics from site 9 were less than half the values observed on 9 March. As was done for site 7, if one plots average plume SF6 concentrations versus the intercept altitude for all site 9 interceptions (Fig. 12), a similar pattern to site 7 is noted. Concentrations peak near the release altitude but are about half of the site 7 peak values. Another difference is that the peak is about 100 m higher in altitude and not quite as sharp as for site 7 (plume more dispersed) . In general, the valley plume intersections would substantiate that a site farther back from the crest allows more time for plume dispersion and better lift of the tracer/seeding material into cloud regions. This is not, however, always the case. Days such as 16, 17, and 19 March, on which strong turbulence was noted at aircraft altitudes, indicate that site 9 is not as effective as site 7, although neither is very effective in getting material to altitudes at or above 2500 m.