East Asia and Western Pacific METEOROLOGY AND CLIMATE

204
Table 1
Rainfall Records of a Tipping-bucket Gauge
(0.205 mm resolution)
NiiflberX hour
of tip \
17 18 19 20
21 22 23 24 1 2 3 4
5 6 7 8
10*
8 5 1 1
20
1 1
44 1
30
3
50 1 3 1
40
27 5
50
60
7
15
1 4
9 0
2
1
Total
1 0 28
115 7 1 12 2
3
* Ending time
RECTIFYING THE RATE-ERROR
The regression equation obtained from the laboratory experiment
is applied to rectify the rate-error for the tip-bucket. Table 2
shows the tip counts per 10-minute (column 3), the rate-error (column
4) computed from the regression equation, and the rectified rainfall
(column 5). Summation of every 10-minute rectified rainfall, from
9:00 am April 22 to 9:00 am April 23 1989, yields a total amount of
110.88 mm which is slightly over estimated by 0.8% when compared with
the actual amount 110,0 mm.
OTHER POSSIBLE ERRORS
Other possible errors of the bucket tipping process were also
observed in the laboratory. These errors are generally quite small
and variable, and consequently are difficult to quantify. For
example, the small amount of rain water remained in a bucket may vary
from time to time and is subject to the surface condition of the
bucket. This variable residual water generally causes a small
fluctuation of the measurement accuracy. It is also observed that the