| In association with the passage of a Tropical Cyclone (TC) around Japan,
the secondary circulation in the region
from the outer side to the center was investigated in detail
by two separately located L-band wind profilers
and the rawinsonde observations
from 1 to 2 October 2002,
for the first time.
As the wind profilers can observe
wind fields not only within rainbands
but also in between,
the mesoscale wind circulation including the vertical wind component
in wide areas
from the lower layer
to the upper layer was investigated.
While the TC center approached the profiler stations,
several rainbands associated with the TC subsequently passed.
Relatively warm, moist inflow with a cyclonic rotation
was observed in the lower-troposphere
while the TC center approached.
The inflow reached the inside
of the main rainband
where the updraft was observed.
Above 5-km height (with temperature below 0°C),
outflow and weak downdraft
corresponding to falling frozen particles
were observed.
It is considered that
the frozen particles formed
precipitating clouds mainly in the outer rainband region.
The continuous wind circulation
transported
water vapor
from the lower troposphere
to the upper troposphere via the vicinity of TC center.
On the other hand,
after the passage of the TC center,
the developed rainband passed,
which was located in the south and southwest quadrant of the TC.
It is suggested with the profilers' data that
the rainband was intensified mainly
by warm and moist outflow below 3-km height. |