Flight 18: Yokota Local 4
This flight was planned in coordination with the ACE-Asia science team which
had
just arrived at Iwakuni MCAS, Japan. A rendezvous with the NCAR C-130 was
planned at 18 Kft over the Sea of Japan to be followed by several hours of proximity
flying to the southwest between Japan and Korea and south along 129E sampling
across a predicted axis of outflow from China associated with a frontal
passage. Some special planned maneuvers included a spiral sounding from
18 Kft to 500 feet at the rendezvous point and another sounding to 12 Kft coinciding
with an overpass of the Terra satellite. With a primary focus on trace
gases for the NASA P-3B and a focus on aerosol properties on the NCAR C-130,
this flight offers an unprecedented level of detail in characterizing the state
of the atmosphere. It also provides a bridge between the aircraft for extending
their datasets in terms of common measurements. These include packages
on both aircraft from U. Hawaii for particle measurements, Georgia Tech for aerosol
composition measurements, and Drexel for SO2 measurements. Other
common measurements include ozone, CO2, and
nonmethane hydrocarbons.
Results:
The P-3B transited at 18Kft from Yokota AFB to the rendezvous point (37N, 133E)
over the Sea of Japan. Along this leg, high variability in all species
were observed (e.g., CO 120-300 ppbv, NOy 400-1500 pptv, SO2 up to
1
ppbv). High chloride values reported by the Georgia Tech group indicating
the presence of sea-salt suggest that this variability was caused by pollution
that had been lifted and wrapped around the low pressure system located to the
northeast. This system was the focus of the DC-8 flight for this day. The
rendezvous was executed as planned and was followed by a spiral descent to 500
feet in broken cumulus clouds. This spiral was intended to allow column
integration of in-situ aerosol measurements of aerosol optical depth for comparison
to radiometer measurements on the NCAR C-130. From this point proximity
flying was executed at several altitudes going southwest to (33.5N, 129E) then
south to (29N, 128E). Along these legs, pollution was encountered mostly
below 8000 feet with the most intense pollution centered around at 3000 feet
(e.g., sustained values of CO 300-350 ppbv, NOy 5-6 ppbv, NO over 700-1500 pptv,
PAN 1-1.5 ppbv. A spiral ascent from 500 feet to 12 Kft and an immediate
descent to 3 Kft was executed under clear skies at (31.5N, 128.5E) to coincide
with the overpass of the Terra satellite. After 3 hours of proximity flight,
the aircraft separated at (29N, 128E) with the P-3B
heading back to Yokota. Flying to the south of Japan, layers of pollution
and stratospheric influence (ozone up to 200 ppbv) were encountered between 12
Kft and 19 Kft in a region predicted to be along a boundary between stratospheric
air and polluted air.