Flight summary, DC-8 Hong Kong-Okinawa 1 03/09/2001
Title: chemical evolution of frontal outflow
Objective: (1) to sample the aged frontal outflow band that had
been previously sampled as fresh frontal outflow on the 0307 flight;
(2) to do laundry in Okinawa
Execution: The frontal outflow sampled on 0307 was forecast to
have been transported along a SW-NE axis over the following two
days, resulting in a band of aged pollution over the western Pacific The
DC-8 flew east from Hong Kong to (20N, 150E) to sample aged free
tropospheric outflow transported S ahead of this band and to reach
the clean air ahead of the front at the easternmost waypoint; it
then flew NW to Okinawa (26N, 128E) to cross and characterize this
frontal band
Results: The flight was a success (1) Biomass burning pollution
plumes were sampled extensively on the eastbound leg west of 135E Further
east, cleaner conditions were found, and the easternmost point
was at the frontal transition On the NW leg to Okinawa, the
polluted frontal band (with CO up to 300 ppb) was encountered at
140-142E, as expected; behind this band and into Okinawa the conditions
were much cleaner, with strongly subsiding air in the free troposphere Free
washing machines in Okinawa afforded astronomical savings over
hotel prices for laundry in Hong Kong
Meteorological Summary DC-8 Hong Kong - Okinawa Overnight
Relevant Flow Patterns
Surface-A
low pressure area was centered near 30N, 155E. A cold front extended
southwest to near 20N, 140E, becoming diffuse farther south of that position. High
pressure was centered near Shanghai. Northerly to northwesterly flow
covered most of the flight area. The major exception was northeasterly
flow between ~ 20 - 25 N.
Middle
troposphere-A subtropical high was located near 20N, 160E. A short
wave trough was located just east of Japan. Westerly winds
covered the flight area. Easterly flow was south of Hong
Kong.
Upper
Troposphere-Flow patterns were similar to those in the middle levels. The
northern part of the flight pattern traversed the right entrance
region of the jet streak.
Relevant Cloud Patterns
Middle
level clouds blanketed the Hong Kong region, but dissipated during
the eastward track. Scattered low level clouds covered most
of the flight track. Most tops were less than 6000 ft.
The
DC-8 strived to pass beyond the surface frontal zone at the eastward
point of the flight. We entered the frontal zone of transition
at 1000 ft, but apparently did not extend completely into the warm
air. The character of the clouds changed and the winds decreased
to ~ 6 kt. However, the wind directions did not shift in the appropriate
way, i.e., they remained westerly.