A STATISTICAL STUDY OF CERTAIN UPPER AIR FACTORS 

 RELATED TO TRADE-WIND RAINFALL IN HAWAII 



B}^ W. A. MoRDY and L. B. Leopold, Pineapple Research Institute of 



Hawaii 



[A bstract] 



A statistical study is made of daily Honolulu radio-sonde data and 

 daily rainfall parameters for days classified as trade-wind days. 

 Variations in the factors of wind velocity, temperature, pressure, 

 humidity, and. stability are tested against variations in the daily average 

 of ten high-rainfall stations and ten low-rainfall stations on Oahu. 



The method is to compute the variance between the rainfall frequency 

 distributions for each of two or three categories of values of temperature, 

 wind velocity, and so on, testing for significance by using the Fisher 

 variance ratio. 



The factors expected to correlate best with the amounts of oro- 

 graphic rainfall on trade- wind days, such as wind speed and direction, 

 moisture and stability in the layers below the subsidence inversion, 

 do not show as high value of F as the factors of temperature and 

 pressure at very high levels. Both temperature and pressure on these 

 days show increasing correlation in the higher layers with rainfall. 



SYMPOSIUM ON CLIMATOLOGY OF THE PACIFIC 



REGION 



THE VARIABILITY OF RAINFALL OVER THE CENTRAL 



PACIFIC 



By C. J. Seelye, Victoria University College, Wellington, New Zealand 



[A bstract{ ^ ) ] 



Rainfall information is conveyed by a series of maps covering the- 

 region between 10° N. and 30° S. and 150° E. and 150° W. These 

 show the average annual rainfall and its percentage variability, the 

 month of greatest and of least average rainfall, the frequency of wet 

 months (taken as those with rainfalls exceeding 150 per cent, of average) 

 and of dry months (under 50 per cent.), the last being given on a seasonal, 

 as well as on an annual basis. 



Brief mention is made of surface winds in abnormally dry and wet 

 years, of the persistence of dry months, and of several speUs of 

 exceptional rainfalls. Throughout the discussion the equatorial dr^-' 

 zone (with its south-eastern extension) figures prominently, as it has a 

 rainfall regime distinct from the rest of the region. Its fluctuations, 

 especially in the east- west direction, appear to produce substantial 

 changes in the rainfall experienced in surrounding areas,- and the im- 

 portance of the westward flow of unmodified Tm air near the Equator is 

 thus endorsed irora the rainfall statistics examined. 



Discussion 



In answer to a question by Dr. Priestley, Dr. Seelye said that un- 

 fortunately no data were available to investigate whether ocean currents 

 might possibly have been the cause of some of the abnormal periods 

 mentioned. 



(1) The full paper is to appear in the New Zealand Journal of Science and 

 Technology. 



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