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The data summaries are 'preliminary' in the following sense.
Aircraft and site images.
(Voice notes by mission scientist, Mike Poellot)
(Data summary by Mike Poellot)
The purpose of this flight was to sample stratus over the DOE CART site. The stratus was rather a single layer of relative uniformity at the beginning of the flight, and it thickened plus a second higher layer developed towards the end. The replicator was not operated during this flight. The stratus was a lesson in cloud physics: the FSSP size distributions showed smaller droplets near cloud base and larger droplets at cloud top, consistent with the notion of cloud forming by an updraft, with cloud top representing the longest growth times. The 2DC probe showed some droplets up to about 300 microns diameter. The EGG and Buck hygrometeors provided the best relative humidities, and the Rosemont temperature probe was best. Microphysics is best represented by the FSSP, 2DC, and 1DP probe data.. Microphysically, it would be interesting to plot the FSSP, 2DC, and 1DP data all together for selected intervals. The stratus was quite thick at times, with water contents exceeding 1 g/cm3. Here are some highlights and images during the flight.
21:22:00 Take off.
Cloud base @ 895 m, 5.4 C
22:04:00 Picture of cloud top.
23:10:00 Picture of instruments as seen through the thick stratus.
23:48:00 Picture of DOE CART site from over the wing.
23:55:04 Landing.
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The purpose of this flight was to evaluate the wind measuring sensors on the Citation (I floated my camera during a high acceleration maneuver). This was also the first flight for the large format cloudscope. Prior to the flight, I adjusted the focus and iris setting in an attempt to achieve reasonable day and night operating conditions. Illumination is provided by ambient light during the day, and by a couple of bulbs at night. The camera has an automatic gain control that adjusts to varying illumination levels, and the operator has the choice of 3 shutter speeds (1/60, 1/1000, 1/4000 or 1/10,000 second). The cloudscope views a circular window with a diameter of 3.87 cm. It has a sample rate of 140 Li/sec at an aircraft speed of 120 m/s, roughly twice that of the PMS 2DP probe. The largest particle size viewable by the scope is similar to the window diameter, 3.87 cm. The smallest crystal or drop observable is about 100 microns. The main purpose of this cloudscope is to seek out the relatively rare large particles that strongly influence radar echo strength.
23:39:25 Take off.
22:28:47 Noticed two insects were collected on the cloudscope during takeoff.
22:50:00 Replicator pump tested and found to deliver 5" of pressure (water equivalent). The seals seem to be working.
00:24:30 Landing.
The mission was cut short, as we observed a developing thunder storm in the distance, and wanted to return to base to prepare for sampling its leading edges.
(Voice notes by mission scientist, Mike Poellot)
(Data summary by Mike Poellot)
(Replicator and cloudscope notes by Pat Arnott)
The purpose of this flight was to evaluate an anvil from a developing thunderstorm. We observed this development during the previous flight. Many of the normal commercial flight corridors were blocked by thunderstorms, so we had limited clearance. We did not sample the tops of the clouds due to air traffic. We found high concentrations of large crystals/aggregates at lower levels.
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Nature has been playing a sick joke on us... the subtropical jet is ridging near the CART site, but about 10 to 50 miles south. It is loaded with very interesting looking cirrus, and is cooking along at about 140 knots. The jet kept acting like it would have a small wave that would penetrate far enough north to be sampled, but it just didn't come through. We would have loved to sample this stream of cirrus, moisture from the south pacific, but it would not go north! Here is a view at 23:45 UTC (7:45 pm local.)
The replicator film transport problem was attacked, and hopefully solved. I replaced the slip clutch on the take up spool with one that is much stiffer (after much fiddle with the slip clutch.) The take up motor should be able to drive the necessary torque, according to the spec. sheets.
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What a day! We saw everything but the kitchen sink. Early in the day, orographically generated cirrus from NM took a ride on the subtropical jet stream and we sampled it over the CART site. The cloud base to top was about 3 km, though we could see through it to the ground. Some rather nice (not Hurricane Nora nice, but respectable) halos and parhelia were photographed, links below. Bullet rosettes were common, though I expect to see some plates mixed in when the replica is evaluated. As the day progressed, outflow from anvils generated in the Texas panhandle mixed in with the orographic cirrus, and the optical depth increased. The cloudscope showed a few particles up to about 0.8 cm near the end of the second flight. The radar crew reported updrafts of 10 m/s near where we finished off, in mixed phase cloud near about 3 km altitude. The flights were somewhat turbulent at higher levels, and generally bumpier than usual.
(Voice notes by mission scientist, Mike Poellot)
(Data summary by Mike Poellot)
(Replicator and cloudscope notes by Pat Arnott)
(Optical displays and cloud photos by Pat Arnott)
(Voice notes by mission scientist, Mike Poellot)
(Data summary by Mike Poellot)
(Replicator and cloudscope notes by Pat Arnott)
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Today was a down/repair day. I decided to install a doubler on the cloudscope to improve the resolution by a factor of two, at the cost of reducing the sample rate. Installation was completed at about 2 a.m.
Medium resolution cloudscope calibration.
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Cirrus was advecting in from southwest Texas and Northern Mexico. Some stratus was present at lower levels. A front off to the west will likely join in later in the evening or morning. The cirrus was somewhat broken, but we did find some large patches for continuous sampling. The cloudscope was used in medium resolution mode; it turned out to have been a decent guess, as the largest crystals seen were between 1 and 2 mm maximum dimension. The cloudscope was operated in two modes: one with the window very warm so that crystals evaporated rather quickly, and one with a moderate window temperature so sublimation was less rapid. The rapid sublimation data looks quite decent for analysis, though the slower sublimation data is easier to view directly from the video tape. Only weak halos were observed if at all, confirming the observation that crystals looked like plate aggregates or plate polycrystals. A few column rosettes were mixed in.
(Voice notes by mission scientist, Mike Poellot)
(Data summary by Mike Poellot)
(Replicator and cloudscope notes by Pat Arnott)
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