Flight 16: Yokota Local 2 (24 March, 2001)
This flight was planned to begin with an intercomparison leg at 17 Kft with the
DC-8. Following the intercomparison, low altitude sampling legs were planned
along the southern coast of Japan and to the north in the Sea of Japan. Model
predictions indicated both regions should have surface outflow below about 6
Kft with cleaner conditions above.
Results:
The intercomparison leg at the beginning of the flight went well. Conditions
were fairly constant for most species, although ozone showed some variability
ranging from 70 to 90
ppbv. Other measurements showed increased structure during a period of
turbulence about 13 minutes into the 20 minute intercomparison. Sampling along
the southern coast of Japan did show surface outflow below 6 Kft as expected. CO
was highly variable with mixing ratios often in the 300 ppbv range and sometimes
exceeding 400 ppbv. NOy and SO2 were consistently at ppbv levels. Crossing
Japan to the north, very different conditions were encountered over the Sea of
Japan. At all altitudes, CO rarely exceeded 200 ppbv and was often around
100 ppbv. Although background levels for all species were lower, several
plumes were encountered from the boundary layer up to altitudes of 10Kft with
ppbv level enhancements in SO2 and NOy (which had a large fraction
attributed to PAN). These plumes also contained large enhancements in CN
and smaller enhancements in ozone, CO, and DP. The Georgia Tech group reported
that aerosol composition was similar to the north and south of Japan indicating
a mixture of dust and anthropognic aerosol. Despite the similarity in composition,
aerosol mass loading was 5 times higher south of Japan as compared to the north.