May 3, 1996
Mission Summary
DC-8 SUCCESS flight #213 [960213] (flight scientist: Eric Jensen)
SUMMARY:
The flight was very successful for the near-field objectives and exhaust
characterization. At the lower altitudes (30 and 35 K'), we sampled the
757 exhaust numerous times with durations up to 2 min.
At 38 K', flying within the
contrail, the pilots were able to stay in the vortex.
Mission Objective
- sample the near field exhaust behind the 757
- photograph the differences in contrails with different
sulfur levels (T-39 will remain within 2 miles of the 757 and
T-39 will periodically offset to a lower altitude)
- study the in-situ chemistry and microphysics of the 757 contrail
(DC-8 will be 5-10 miles behind the 757 and about 300 ft. below it, and
DC-8 lidar will only be used in forward scanning mode
when the separation to 757 is more than 11 miles)
- investigate with the ER-2 from above the
radiative properties of the contrails created by the 757.
Flight Track
Flight Log
OPERATIONS
FLIGHT PLAN:
The flights should take about 4 hours.
We will stager takeoff with the ER-2 going first, followed by the 757/T-39/DC-8.
All aircraft will proceed to the CART site at an altitude of 37 K',
or as high as possible
Then the aircraft will fly racetrack patterns centered on the CART site.
The T-39 will remain within 2 miles of the 757, and will periodically offset to
lower altitude.
The DC-8 will be 5-10 miles behind the 757 and about 300 ft. below it.
- L-L: 757 burns low sulfur fuel in left engine
and low sulfur fuel in right engine
- H-L: 757 burns high sulfur fuel in left engine
and low sulfur fuel in right engine
- H-H: 757 burns high sulfur fuel in left engine
and high sulfur fuel in right engine
A general outline of the 757 flight pattern is given below.
L-L: transit to CART site,
ascend to highest possible altitude (37-39 kft), 30 min upwind leg 1
L-H: turn
H-H: 30 min downwind leg 2
L-H: turn, ascent to 41000ft if possible
L-L: 30 min upwind leg 3
L-H: turn
H-H: 30 min downwind leg 4, on turn descend to altitude
where no contrail is made
L-L: 30 min upwind leg 5 (T-39 returns home)
H-H: 30 min downwind leg 6, return to Salina final
DC-8 will stay for an additional 30 min upwind leg direct over CART site
DC-8 will fly a square box with 30 sec legs at a
convenient altitude and do pitch and yaw maneuvers for MMS calibrations and return
TAKEOFF/LANDING
The DC-8 left Salina at 17.35 UTC (12.35 local time) and
returned to Salina at 22.50 UTC
FLIGHT REPORT
The flight was flown as planned with the following exceptions:
The first two legs
were flown at 35 K', with the aircraft just barely conning.
The DC-8/757 separation
ranged from about 4 miles to 7 miles.
Legs 3 and 4 were flown at 38 K' with contrails
about 5 miles long.
The aircraft separation ranged from about 4 miles to 9 miles.
We were delayed about 20 min.
before our descent to 30 K', so leg 5 was flown half
L-L and half H-H.
We flew the final leg at 41 K' over the CART site, and stayed at
41 K' while heading home to have a long single altitude calibration leg.
Flying in
the vortex was very rough(!), especially during the 38 K' legs.
METEOROLOGY-REPORT
OBSERVATIONS:
Non-persistent and short contrails
INSTRUMENT STATUS
All instruments are functioning.
- BALLENTHIN: No problems
- BAUMGARDNER: No problems
- BRUNE: No problems
- CHAN: No problems
- COGGIOLA: No problems
- COOPER: No problems
- DADS: RHI was flagged several times.
- FERRY: No problems
- GARY: No problems
- GERBER: Probe did not work properly. Unknown prognosis.
- HAGEN: No problems
- HALLET: No problems
- HEYMSFIELD: Problem with focusing motor on VIPS.
- HUDSON: No problems
- LAWSON: No problems
- RODGERS: No problems
- SACHSE: No problems
- TALBOT: No problems
- TWOHY: No problems
- UTHE: No problems
- VALERO: Zenith TDDR failed late in flight.
- WEINHEIMER: No problems
Mission Highlights
- no crystals were detected in visible contrail at 4-5 miles, but MASP did
see high concentrations (100 x background) at these times
- ice crystals
were probably too small to be detected with the replicator,
the VIPS, the cloudscope, or
the Lawson probe
- OH counts increased by factors of 5-10 over clear air
- HO2 counts decreased by factors of 2-3
- CIMS measurements did indicate more
SO2 during the use of high-sulfur fuel by the 757
- Hudson reported very
large increases in CCN concentrations: 10000/cc vs. 100/cc background.
CCN/CN ratios at 38 K' were much higher
than the 1% values previously reported
in exhaust plumes
- at 30 K', the CCN/CN ratios were much smaller
- volatility
measurements indicated at least half of the CCN are likely sulfuric acid
- 10-20 ppb NO spikes were consistenly seen in 757 exhaust
with a maximum
value of 80 ppb
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