DC-8 SUCCESS flight #212 [960212] (scientist: Eric Jensen)
SUMMARY: The basic flight went well. After a few hours of searching, we found an ideal wave-cloud east over Boulder, Colorado, at about 39 K' (around -63 C). We flew about 2.5 patterns through the cloud. The vertical displacement in the wave appeared to be about 2000 ft. The vertical displacement was also evident in the MTP measurements. Measurements made near the leading edge should be very useful for understanding ice nucleation processes.
OPERATIONS
FLIGHT PLAN:
We will transit to Medicine Bow Wyoming
(41 deg. 22 min., 106 deg. 19 min.) at 35 K' and
determine whether wave-clouds are present.
If the clouds are absent or too high to
sample, we will fly to a range in northern Wyoming
(44 deg. 22 min., 107 deg 10 min.)
and fly along the range to look for wave-clouds.
Starting near the highest point in the wave-cloud,
we will fly upwind, following
potential temperature surfaces,
through the leading edge of the cloud and upwind 15 min.
Then we will turn and fly back up our exhaust trail back into the cloud.
Next, we will turn 270 deg. and fly a 10 min. leg normal to the wind,
along the leading edge of the cloud.
Finally, we will execute a dog-leg turn and fly another
10 min. leg along the leading edge of the cloud,
attempting to intersect our exhaust
trail flowing into the cloud.
This pattern should take about an hour.
We will repeat this pattern 3 times.
After the first pattern, the ER-2 should
arrive and fly a compact pattern above the leading edge
of the cloud. No strict
coordination with the ER-2 is required
other than sending them the point on our
track normal to the wind at the leading edge of the cloud.
TAKEOFF/LANDING
The DC-8 left Salina at 16.35 UTC (11.35 am local time) and
returned to Salina at 22.45 UTC
FLIGHT REPORT
We proceeded to Medicine Bow at 35-37 K', but no wave-clouds were apparent.
Extensive cirrus were visible at lower altitudes. Next, we shifted the pattern
to the southeast (41.48 deg, 105.58 deg), but again, no waveclouds were nearby.
We were nearly ready to give up when wave-clouds were spotted to the south.
We extended our N-S (cross-wind) leg
about 50 miles south to get in to the clouds.
We flew the designated pattern twice. On the first pattern, we stayed at 39 K'.
On the second pattern, we descended to 37 K' at the beginning of the upwind leg.
This descent appeared to maintain constant potential temperature. When we
penetrated the leading edge the second time, we ascended to 41 K'. We appeared
to be skimming the cloud-top at this altitude.
At the end of the second pattern, we turned back south along the leading edge
and then flew east downwind through the cloud at 39 K'. We maintained constant
altitude for 15 min. downwind of the cloud, and then headed home.
METEOROLOGY-REPORT
OBSERVATIONS: As expected, tropopause was low and warm: near 10 km
and -50 C. Popcorn cumulous was present at about 3-5 K'.
INSTRUMENT STATUS
All instruments are functioning.