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measurements in the salt plume. This was made possible by the son of Dr. Daniel Rosenfeld, Mr. Amir <br />Rosenfeld, who wrote a software package that: 1) accepts the GPS coordinates of the project aircraft in flight <br />and presents their tracks in real time on the screen of a lap-top computer in the cockpit of the lead cloud physics <br />aircraft, 2) marks the positions of the seeder and cloud physics aircraft and/or an event, such as the detected <br />"hit" of SF6 gas and then repetitively navigates back to this point as it drifts with the ambient wind, 3) displays <br />along the track of the cloud physics aircraft when it was in cloud, 4) displays in real-time the plots of measured <br />aircraft parameters such as cloud droplet sizes and cloud liquid water contents as a function of time, and 5) <br />presents the aircraft navigation information in a form useful to the pilot. All of this is illustrated in Figure 1, <br />which gives the presentation available in the aircraft cockpit during a portion of the flight on May 31, 2005. <br /> The content of Figure 1 needs careful exposition. North is at the top of the figure and tick marks for <br />latitude and longitude are on the left and top, respectively. The tracks of the base-seeder and the monitoring <br />cloud-physics aircraft are shown in yellow and green, respectively. At the time of the depiction (205846 GMT) <br />the base seeder aircraft had ceased seeding and moved off to the southwest. The shaded areas along the track of <br />the cloud physics aircraft show when it was in cloud. The initial seeding in this case seeding was at 205235 <br />GMT, so the depiction is roughly 6 minutes later. The track of the seeder was essentially NW-SE during the <br />seeding. Note that most of the monitoring took place in the cloud slightly to the ENE of the seeding activity. <br />o <br />This makes sense since the GPS-derived winds at the flight level of the cloud physics aircraft was from 257at <br />-1 <br />11 m s (22 kts), so the cloud had drifted to the ENE. <br />-3 <br /> An inset plot for the cloud liquid water (red plot, left scale in gm m) and for the voltage for the SF <br />6 <br />detector (green plot, right scale) is given in the upper left of the figure where the most recent time is shown on <br />the extreme right. Examination of these plots reveals a major β€œhit” of SF, leaving no doubt that the cloud <br />6 <br />physics aircraft had intercepted the seeded plume, making it possible to compare cloud microphysical structure <br />within the plume to the structure outside the plume.Based on careful ground tests it was determined that there <br />was a lag of 7 sec between the intake of SF gas and its detection by the detector. The inset plot has been <br />6 <br />corrected for this lag, amounting to about 700 m. The portion of the green track of the Cheyenne where a hitof <br />SF was observed is shown in red on the track. Upon marking this hit in real time, it ispossible to return to this <br />6 <br />seeded volume time and again as long as it can be done safely. In this case, however, the overall cloud had <br />become quite vigorous, making it unwise to attempt repetitive traverses of the affected cloud region. Multiple <br />returns to the originally seeded area were possible, however, in the second case on this day. These will be <br />discussed extensively in the results section of this Final Report. <br />22 <br />