Flight 17: Yokota Local 3
This flight was planned to investigate air-sea exchange through eddy correlation
measurements based on high frequency sampling of SO2 and CO2 and
data from TAMMS. The flight was planned for the marine boundary layer to
the southeast of Japan (vic. 34N, 145E) where clear air and subsident conditions
were expected to prevail, although the level of heterogeneity to expect in the
airmass was uncertain. Potential problems with a volcanic plume from Miyake
Jima were forecast by the U. Iowa model. A coincident overpass of the Terra
satellite also offered an opportunity to provide a profile of aerosol properties
useful in the validation of MISR.
Results:
On the initial descent into the boundary layer southeast of Japan, intense pollution
was encountered below 4000 ft with 2 ppbv NOy, 20 ppbv SO2, up to
300 pptv NO, evidence of new particle formation, etc. This layer was most
likely a mix of pollution and volcanic emission from Miyake Jima. Stacked
legs of 30 minute duration were flown in an L shape along and across the wind
at 500, 800, and 1200 feet with a porpoising leg at 1800 feet. While conditions
were not homogeneous, variations along the legs were consistent with one end
being polluted and the other being relatively clean. After another sounding,
another set of stacked legs were flown more to the south at altitudes of 500,
700, 1000, and 1200 feet. While the second set of legs began with more
homogeneous conditions, the plume from Miyake Jima was clearly encountered along
a portion of each leg with highly elevated SO2 and CN with no response
in other pollution tracers.