R.Manasseh Fluid Dyn Papers
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The flight began at 0641. Winds over the inland part of the metropolitan area
were south-westerly at 
over the southern leg (0658-0715) and
of the same magnitude but north-westerly over the northern leg (0722-0743).
Levels of pollutant indicators were negligible. The coast at Newport Beach was
crossed at 0739. As the aircraft descended below 200 m, a zone of pollutant
indicators was found over the sea,
extending from the coast to about 10 km offshore. The aircraft then climbed
above 200 m, so it is possible that the zone extended further, but only below
200 m. An ocean-leg run was made from 0750 to 0805, running parallel to the
coast and 1-3 km offshore; it was in a vertical sawtooth pattern from
150-200 m down to 60 m. At the start of the ocean leg the wind was
south-westerly at 
and hence offshore. However, at 600 m the
wind was northerly, thus the offshore flow was a low-level phenomenon.
The ocean-leg run identified a substantial zone of pollutant indicators
beginning with the region initially noticed off Newport Beach and rising to a
significantly higher level, peaking just north of the entrance to Botany Bay. A
band of brown air could be seen. Further runs along the ocean leg at a constant
altitude of 80-90 m were made immediately, first returning northwards on the
same track, then southwards about 5-7 km out to sea, taking from 0805 to 0843.
Winds were westerly (offshore) at . The peak in pollutant
indicators appeared just at Sydney Heads (the entrance to Sydney Harbour) in
the run close to shore and the zone extended from Maroubra to Palm Beach; on
the run further out, the pollutant indicator levels were lower. A line of
clouds was visible over the land and cumulus clouds were visible 50-70 km
offshore. On the second southwards run there appeared to be less brown air.
A further northwards run, taking from 0843 to 0857, was made at 80-90 m and close to shore up to Sydney Heads, then out to sea until the pollutant indicators dropped to negligible levels; this occurred about 20 km out. The aircraft returned southwards 20 km from the coast, reaching point `S' at about 0908.
Estimates of the lag time in the response of the chemistry instruments under operational conditions were made. These suggest that the true locations of the peaks in pollutant indicators would be approximately 1 km earlier on the flight track than quoted above. This indicates that the 5-10 km displacements in pollutant indicators between runs were genuinely caused by wind advection or other environmental effects.
Temperatures during runs on the ocean leg were 
, increasing
over the hour during which these runs occurred (from 0806 to 0908) as the sun
rose. A drop from 
was notable at the mouth of the Hawkesbury; a
drop of 
occurred just north of the entrance to Botany Bay and a
drop of 
occurred just off Sydney Heads.
R.Manasseh Fluid Dyn Papers
R.Manasseh Fluid Dyn Home