East Asia and Western Pacific METEOROLOGY AND CLIMATE

Q \
ed atmospheric processes *
2. MODEL'S INITIAL FIELD AND DETAILS OF THE NUMERICAL SCHEME
Fig,l illustrates the movement of a surface cold high's center
and cold front during a cold surge episode over the Sea during 23-
29 December 1982. The episode can be partitioned into three stages:
initial (23-24), active (25-2) and decaying (28-29). The initial
field was taken from ECMWF 5°X 5° grid data at 2000 BST, 24 December
of the year and the initial SST field from the monthly mean of
December 1982.
Designed were three experiments*ALL for the experiment involving
all physical factors of the model; DH for the adiabatic; and NM for
the non-mountain experiment*
3. RESULTS OF EXPERIMENTS
1) ALL Experiment
The 72-h integration indicates close similarity between the calculated
and observed situation on a large-scale basis,except that a
small low was not predicted to the NE of Japan.Horizontal grid spacing
of the model might be too large to show smaller-scale disturbance.
This, however, has no significant effect on the problems to
be discussed*
The near-surface flow evolutions in the integration between 12
and 48 hr are depicted in Fig.2. In Fi#.2d, solid circles (A^) denote
the position of the anticyclone's center and open circles (Vv)
of the maximum NE wind of J m/s, at the i-th hour of integration.
It can be seen that the high 1 s center is around 43°N, 95°® at 12 h
and then moves southeastward, reaching the middle and lower Chang-
Jiang at 60 h. The leading edge of the surge, at 12 hr integration,
is found at 15°N with the maximum NE wind center of 10 m/s located
in the middle Changjiang. At the 24 h, the robust surge crosses the
whole South-China Sea, its leading edge arriving at the equator,
with the maximum wind region > 8 m/s around 22°N off South-China
shores. Then a narrow belt of stronger cold air in the form of an