ON THE FLUCTUATION OF THE KUROSIWO AND THE OYASIWO 839 



ing year. It was large in July, September and late October, and small 

 again from November till February. 



In 1952 the Kurosiwo was strong from the last decade of Novem- 

 ber till February and became strong again in early April along the 

 meridians 143°E and 149°E, reaching the average intensity in June 

 and July, but the -warm current stopped spreading northwards in Aug- 

 ust at a lower anomaly of temperature. But it greAV warmer again and 

 reached the average temperature in September. After that it had the 

 average intensity. The Oyasiwo was strong along the meridians 142 °E 

 and 147°E in March and April. In August, the Oyasi^vo ran south- 

 wards strongly along the 145 'E meridian. "^ The ratio of the Kurosiwo 

 became smaller from February and ^v^s generally small all year with a 

 maximum in September, which is of the a\'erage value in summer. The 

 ratio of the Oyasiwo had maxima in April, July and September. 



The ratio of the Kurosiwo seems to vary periodically. If there 

 were a maximum in February, 1950, though it "was not observed owing 

 to bad weather condition, the maxima of the Kurosi^vo's ratio have the 

 follo^dng time series: Oct. 1948, 9: July 1949, 7.5; Feb. 1950, 7^; Sept. 

 1950, 8^; June 1951,^; Feb. 1952, 7_^; Sept. 1952. 



The period is about seven-nine months. On the other hand, the 

 period of the wind stress shear is about six-eight months." The periods 

 of the oceanic current and the wind do not coincide with each other, 

 and the reason why the cm-rent's period is lengthened will be found in 

 a complex combination of the wind-driven, thermo-haline circulation, 

 etc. 



3. Conclusion 



By the comparison mentioned in the above section, ^ve can recog- 

 nize that the area occupied by the oceanic current is an important meas- 

 ure to represent numerically the intensity of the current or the oceanic 

 state, and the period of the Kurosiwo's fluctuation is about seven-nine 

 months. Though we may have to make further investigation of the 

 difference in the periods between the Kurosiwo and the wind, it is cer- 

 tain that we have made a step toward the forecast of oceanic conditions. 



