DC-8 SUCCESS flight #208 [960208] (scientists: Brian Toon and Eric Jensen)
SUMMARY: The basic flight went very well. All of the instruments
are functioning, with small problems left to be worked out.
This was an excellent cirrus sampling flight. Cirrus clouds were sampled
at a very cold tropopause and appear to be very interesting. The T-39
also got good particle measurements in the DC-8 exhaust/contrails.
OPERATIONS
FLIGHT PLAN:
We will initially fly to a point 45 mi. downwind of the CART site (the wind is
forecast at 300 deg., 50 knots). We will then fly a 15 min. leg upwind over
the CART site at 20 K'. Then we will fly a climbing leg
(not necessarily directly
aligned with the previous leg) to the downwind point at 24 K'. Next, we will
fly a level upwind leg at 24 K', then a climbing leg to 30 K', then a level leg
at 30 K', then a climbing leg to 37 K', then a level leg at 37 K'. At the
end of the upwind leg at 37 K', we will turn around, drop about a hundred feet,
and attempt to visually pick up and fly into our contrail. Then we will fly
another level leg upwind at 37 K' (hopefully in our contrail). Once we are
slightly upwind of the CART site, we will fly 3 Lagrangian circles and spiral
down over the CART site. We should have time to repeat the entire pattern.
The T-39 will follow us as far as possible: either until they run short of
gas or until the clouds are too thick for coordinated flying. The ER-2 is
grounded due to high winds.
TAKEOFF/LANDING
The DC-8 left Salina at 16.30 UTC (11.30 am local time) and
returned to Salina around 23.45 UTC
FLIGHT REPORT
The DC-8 climbed to 30 K' and transited to a point about 50 miles downwind
of the CART site, with the T-39 sampling its exhaust. A 15 min. leg upwind
over the CART site was flown at 30 K'. Then legs at 33 and 37 K' were flown.
At 37 K', we attempted a fly back up to our contrail, and three circles were flown
to intersect our contrail. Finally, we spiraled down to 30 K' over the CART
site.
The along-wind, ascending legs pattern was then repeated with legs at 29,
33, 37, 39, and 41 K'. The legs at 39 and 41 K' were repeated to sample
our own contrails. After these legs, we flew three circles, sampling our own
exhaust/contrails. Finally, we spiraled down over the CART site.
METEOROLOGY-REPORT
FORECAST:
Cirrus clouds over the CART site are forecast throughout the day, getting
thicker with time. A front is moving in, and the tropopause should be lifting.
This condition should be ideal for persistent contrails.
OBSERVATIONS:
Patchy cirrus were observed during the first few legs of the first pattern.
During the end of the first pattern and the beginning of the second, the CART
site region was in a hole in the cirrus. Subsequently, deep cirrus moved in,
with tops sometimes higher than 41 K'. The legs at 41 K' were in very cold
cirrus (T = -68 C). Contrails generally did not persist more than a few minutes.
Observation of contrails behind the DC-8 indicated
that they typically dissipated
just after the vortices broke up. Ground observers indicated that we only
conned on the first of our three final Lagrangian circles.
INSTRUMENT STATUS
All instruments are functioning.
