Geoscience Reference
In-Depth Information
Table 1. Comparison of calculated precipitation (mm) to observed ones at Kangnung
city from December 7-9, 2002. ( ) denotes snowfall amount.
Date
Comparison
12:00
18:00
00:00
06:00
12:00
18:00
00:00
06:00
12/07
Observed
6.6
7.0
3.0
3.5
6.5
4.0
1.2
4.6
to
(snow
(0.0)
(0.1)
(0.2)
(2.8)
(3.4)
(0.1)
(0.2)
(8.6)
amount)
12/08
Calculated
4.5
7.0
2.0
2.0
6.5
8.0
1.0
0.0
snowfall amounts measured at Gangwon Regional Meteorological Adminis-
tration located in Kangnung city. The general tendency of calculated rain-
fall amounts well matched with observed ones, except for two cases. As at
18:00 LST, December 8, the cloud base very closed to the ground surface
of the city, ice droplets falling toward the ground became rain droplets at
air temperature of 3 C, through melting process of ice crystal to be water.
Thus the reason why observed snowfall amount was too small with 0.1 cm
might be attributed to melting of snow into rain, and result in calculated
precipitation amount to be twice greater than observed one (Table 1).
When both calculated and observed wind directions at 06:00 LST,
December 9 was north-westerly (340 ) parallel to the coast and this wind
did not induce sucient moisture advection from the sea into the coast to
make a great cloud, showing calculated value of precipitation to be zero and
resulting in a great discrepancy to observed one. Probably, this discrepancy
might be due to the exaggeration or reduction of moisture modification by
the model, under unknown local effect or by a couple hours faster move-
ment of calculated snowfall band (or rainfall band) by the model toward the
coast than the observed one. Even if partial discrepancy between calculated
and observed ones still existed, the general tendency of calculated rainfall
amount well matched with observed one.
4. Conclusions
During the snowfall period, north-easterly wind and easterly wind under the
existence of a high pressure system in north and a low pressure in south
of Korean peninsula prevailed in the eastern mountainous coastal region
and sensible heat flux induced a great amount of evaporation from the sea
surface into the lower atmosphere. Then north-easterly could induce a great
amount of moisture from the sea toward the top of mountain in the west.
The uplifted moisture should be cooled down and saturated, resulting in the
formation of ice and rain particles inside low cloud and sequentially a great
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