Flight summary, DC-8 Okinawa-Hong Kong 03/10/2001

Title: China outflow to Yellow Sea  

Objectives: (1)  to sample boundary layer outflow from China to the Yellow Sea around a surface High over the western Pacific; (2) to sample frontal and convective outflow along the transect from the Yellow Sea to Hong Kong  

Execution:  The DC-8 headed NW and then N from Okinawa (26N, 128E) well into the Yellow Sea (38N, 125E) with extensive profiling in the boundary layer  It then flew along a N-S transect back to Hong Kong (22N, 114E), mostly at high altitude but with a vertical profile and a long boundary leg getting into Hong Kong  

Results: The flight was a success  (1) Extensive pollution was observed in the Yellow Sea, with considerable structure  At 32-34N and below 5Kft CO concentrations approached 500 ppbv and CO2 was in excess of 380 ppmv Further N the air below 5Kft was cleaner, as expected from the shift in surface winds (now blowing from N Korea) but a highly polluted layer was sampled at 8 Kft  (2) The transect S into Hong Kong identified strong biomass burning pollution plumes from 20 to 30N and at 28-32 Kft altitude (CO in excess of 200 ppbv), and a pollution layer of considerable latitudinal extent was also observed at 10 Kft

Meteorological Summary DC-8 Okinawa to Hong Kong

Relevant Flow Patterns
         Surface-An anticyclone was centered between southern Japan and Okinawa, with clockwise flow around it.  Thus, surface winds in the Yellow Sea mostly were from the south.  The exception was northerly flow at the extreme northern point of the flight track.  Farther south, easterly flow covered the southern half of the flight track. No fronts were in the area.

         Middle troposphere-The low level anticyclone near Shanghai dissipated by the 10,000 ft level. However, a short wave trough was oriented along the western shore of the Yellow Sea.  A major subtropical anticyclone was centered near 15N, 150E.  Westerly flow covered the flight track in the middle troposphere.

         Upper troposphere-Flow patterns were similar to those in the middle levels.  The jet stream was located near 35N.  The flight track entered the right rear (entrance) region of the jet streak that mostly extended southeast of Okinawa.  Westerly flow covered the area. Trajectories indicated that some of this air had passed over parts of Southeast Asia.

Relevant Cloud Patterns
         The Okinawa area had extensive clouds at low, middle and high altitudes.  These clouds generally were located between 22 - 30N. Conditions were much improved over the Yellow Sea, with only scattered stratocumulus and isolated cirrus being observed.