East Asia and Western Pacific METEOROLOGY AND CLIMATE

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there is only a minor difference among these four grids. For grid A
(381km), the maximum value of RC is larger than that of RL, while for
grid D (47.625km) the value of RL is much larger than that of RC and
approaches the maximum amount of RT. The contribution of the two kinds
of condensation to total
precipitation can be presented
by the areal mean
values of RT, RL and RC.
The proportion of RL in
RT increases with the
increase of resolution. It
is about 38% for the
381km grid and increases
up to 90% for the
47.625km grid. On the
contrary, the proportion
of RC in RT decreases as
the resolution increases.
It is about 62% for the
381km and only 10% for
the 47.625km grid. This
is identified by the
24-hour forecasts of RT,
RL and RC predicted by
the grid A and D(Fig.5).
For the 47.625km grid,
the distribution of RT
almost coincides with
that of RL. But the
distribution of RT predicted
by the 381km grid
is similar to that of RC
rather than that of RL. Fig.4. Maximum(top) and areal mean(bottorn)
amounts of RT, RC and RC
predicted by grid A, B, C and D.
V. Summary
1. The operational limited area model used at BMC is fairly simple.
But the operational results show that (1) the model is stable and a
continuous service can be provided and (2) the model has some merits in
forecasting the movement and development of some synoptic scale
systems, such as front, cyclone, vortex and the associated precipitation.
2. The precipitation forecast is effectively improved, in terms of both
rainfall area and amount by increasing the horizontal resolution.
3. The relative contribution of covective condensation, computed by
Kuo's scheme, in fine mesh grid models is not as much as in coarse grid
models. The grid scale condensation dominates in the total precipitation
when the resolution is high enough (less than 50km ).