ON THE FLUCTUATION OF THE KUROSIWO 

 AND THE OYASIWO 



By Tosio Nan'niti 



Meteorological Research Institute, Tokyo, Japan 



Abstract 

 Using the area occupied by the oceanic current in a fixed section, 

 the author represents on a graph the intensity of the Kurosiwo and the 

 Oyasiwo as mentioned in his previous paper. The occupied area has 

 one or two maxima a year. The period is about seven to nine months 

 as shown in accompanying figure. 



1. Introduction 

 To represent the intensity of the Kurosiwo and the Oyasiwo nu- 

 merically, the author adopted substitute quantities Avhich are easily 

 calculated; they are the ratios of the area occupied by the Kurosiwo or 

 the Oyasiwo to the whole observation area in the fixed section on the 

 parallel of 38°18'N. In the case of the Kurosiwo the calculation is 

 limited to 300 m depth, and in the case of the Oyasiwo to 600 m 

 depth. ^ The author will copy the values published by the Central Me- 

 teorological Observatory for the sea conditions, and will compare these 

 with his quantities, the ratios of the Kurosiwo and the Oyasiwo. 



2. Comparison of the Results Obtained by the Author's Method 

 WITH THE Actual Oceanographical Conditions 



The results obtained for the ratios of the Kurosiwo and the Oya- 

 siwo are shown in the following figure. If these values correspond to 

 the actual oceanographical conditions with small differences, we would 

 have an important means to represent and forecast oceanographical 

 conditions. 



The actual oceanographical conditions quoted here were inves- 

 tigated by the usual method using the distribution patterns of tempera- 

 ture, chlorinity, etc. 



We observed that the intensity of the Kurosiwo was less in 1949 

 than in the preceding year. In 1948 the Oyasiwo was somewhat strong- 

 er in early summer and late autumn, but it was weaker in other months. 

 On the other hand, the Kurosiwo was stronger, especially in summer, 

 and the warmer anomaly of the surface water temperature was largest 

 in August.- The ratio shows that the Kurosiwo's area was large in late 



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