Flight 15: Yokota Local 1
This flight to the east of Japan was intended to profile across a frontal boundary
near 150E, sample beyond the front, and cross the frontal zone again on the return
to Yokota.
Results: Heading out to the frontal zone, vertical profiles revealed ozone
to be about 10 ppbv lower beyond the front. CO values were similar below
8 Kft and were lower beyond the front at higher altitudes. CO values were
rather low both behind and beyond the front falling mostly in the 100-200 ppbv
range. The vertical ascent at 40N fell within the frontal zone and showed
almost no gradient in the CO (120 ppbv) and ozone (60 ppbv)profiles while relative
humidity was near 100% between the surface and 15 Kft. Returning across
the frontal zone, CO values remained less than 200 ppbv until reaching the boundary
layer. At 5.5 Kft, evidence of new particle formation was reported by the
UH group, and both ultrafine and fine particle counts showed a strong correlation
with variations in NOy. On the final boundary layer run, polluted air with
CO up to 400 ppbv and NOy up to 3 ppbv were observed. PAN was measured
to be the dominant NOy species through most of the flight often accounting for
40-50% of total NOy. On the approach into Yokota, strong pollution encountered
at 4 Kft included CO in excess of 700 ppbv, CO2 in excess of 400 ppmv,
NOy greater than 20 ppbv, and PAN over 3 ppbv.