East Asia and Western Pacific METEOROLOGY AND CLIMATE

489
CONCLUSIONS
Seasonal rainfall forecasts using simple regression equations yield relatively unsatisfactory
results with mean absolute errors in excess of 15%. The only exception is the ELNN method
which gives a mean absolute error of about 13%. However, a sea surface temperature trend in
ELNN is not well correlated with the summer rainfall in Hong Kong, with r < .5 in most cases and
are not significant at the 5% level.
The multiple regression method has improved the forecast accuracy to a mean absolute error
of slightly less than 13% and a standard deviation of about 10%. At the same time a high
correlation with values of 'r' ranging from .72 to .94 can be achieved. Despite this, there is still a
great deal left to be desired on quantitative rainfall forecasting methods as errors of over 35% still
appear in 2 out of the 14 forecasts during the period 1975-1988.
The multiple correlation methods predict summer rainfall in Hong Kong for 1989 to be in the
region of 1948.1 mm - 2161.2 mm, a value which has yet to be verified but appears at the moment
to be in the right ball park.
ACKNOWLEDGEMENT
The authors are most grateful to their colleague, Mr. K.W. Li for his devoted effort in all the
statistical computations involved in this study.
REFERENCES
Bell, G.J. 1964 Preliminary Report on Hong Kong Rainfall
1974 Quasi-biennial Variations in the Tropical Troposphere,
Royal Observatory Occasional Paper No. 28
1976 Seasonal Forecasts of Hong Kong Summer Rainfall,
Weather 31 No. 7 pp 208-212
1976 Seasonal Forecasts & Northern Hemisphere Circulation
Anomalies, Weather 31 No. 9 pp 282-292
1977 Changes in Sign of the Relationship between Sunspots
and Pressure, Rainfall and the Monsoons, Weather 32 No. 1
pp 26-32
Fritz, S. 1985 The Aleutian Low in January & February - Relative to
Tropicl Pacific Sea Surface Temperature, Monthly Weather
Review February 1985 pp 271-275
Reynolds, G. 1978 Two statistical Heresies, Weather 33 No. 2 pp 74-76