Flight 12: Hong Kong Local 4
The P-3B took a track heading north to the east of Taiwan along
124.5E. This track was selected to attempt to sample a stratospheric
intrusion expected just north of 26N. Returning to Hong Kong
a short leg of high altitude sampling into the South China Sea
was planned to look for potential biomass burning outflow.
Results: A layer of elevated CO and NOy was observed on
the initial ascent between 7 and 10Kft. This layer was not
present on the initial descent about 1 hour later. As in
previous flights to the east and north, boundary layer legs were
characterized by high variability in NO, NOy, SO2, and
CN suggestive of shipping lanes. Numerous ship sightings
were also reported from the cockpit. An uncooperative air
traffic control representative prevented sampling of the expected
stratospheric intrusion by forcing the P-3B to stay below 7.5Kft
north of 26N. On reaching the South China Sea, conditions
were fairly clean up to 20Kft with CO decreasing with altitude.
Between 20-24Kft, a few thin layers were observed with elevated
CO, NO, NOy, O3, and CN. Although not dramatic,
CO at 24Kft was higher than that at 20Kft. Another layer
at 22Kft contained enhanced O3 and NOy which were anticorrelated
with dew point.