East Asia and Western Pacific METEOROLOGY AND CLIMATE

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mature convections. Satellite pictures showed that the heavy rainfall
event over southeastern Taiwan in the morning hours of May 13,1983,
with hourly rainfall of 60.4 rnn and daily rainfall of 173*9 urn, was
generated by the interactions of outflow boundaries from two preexisting
IvCSs (31). Also,the heavy rainfall case of May 28,1981 over
northwestern Taiwan, which had an hourly rainfall of 88.7 rrm, was
perhaps attributable to the interactions between the Ivfei-Yu front and
a gust front from a mature PvCS, Chiou and Liu (52) suggested that the
heavy rainfall event of June 3, 1984 was probably initiated from an
arc cloud along a gust front. Therefore, it seems clear that we have
to better understand the role of the outflow boundary in order to
improve the heavy rainfall forecast in the Msi-Yu season.
6. TOPOGRAPHIC EFFECTS
Taiwan is an island with complex terrain. The Central Mountain
Range oriented in a nouth-south direction across the island with an
average height of 2000 m (the peak height is about 4000 m). This
topography is responsible for generating various types of local
circulations affecting the local weather. Also, it interacts with
atmospheric flows and circulation systems. For example, the Mbi-Yu
front deforms over Taiwan and mesoscale disturbance often forms
primarily due to the blocking of the topography. Chen (11) observed
that theMei-Yu front over the east side of Taiwan moved faster than
that over the west side due to the topographic effects. A similar
situation was also indicated in the long-term mean frontal speed in
the Mei-Yu season which showed a faster speed to the east of Taiwan
and to the east of the southeastern China coastal mountain ranges.
Besides, the Mbi-Yu front often breaks into eastern and western
sections by the Central Mountain Range. As also pointed out earlier a
mesolow often forms over northwestern or southeastern Taiwan primarily
due to the topographic effect (Fig.5, 11).
Climatological data showed that the monthly rainfall in June
increases from the Taiwan Strait eastward and reaches a maximum over
the Central Mountain Range then decreases over the eastern side of the
mountain. This is also true in the tvfei~Yu season. As shown in Fig.6
(11) a marked contrast in rainfall existed to the west and east sides
of the mountain indicating the importance of topographic effect. The
frequency of heavy rainfall events over northern Taiwan reached a
maximum in the night time hours (24) suggested that the topography
possibly affect the local rainfall through the induced diurnal local
circulations. In addition, the mesolow formation over western Taiwan
enhanced the low level southwesterlies and thus a stronger topographic
lifting and more active convections over the area. (30,36).
7. OVERVIEW OF T/MEX
This section briefly describes the project of Taiwan Area
Mesoscale Experiment (T/MEX), more detailed information can be found
in Kuo and Chen (62), The field phase of X%£X extended from May 1 to
June 29,1987 covering thirteen Intensive Observing Periods (IGPs) and
ten P-3 aircraft flight missions. The participants from the United