Normally the air temperature in winter at Oki-no-Tori Sima changed up and down at a temperature range of about 1℃. This rapid change of air temperature was due to the cooling of Winter Monsoon and the heating of South warm wind and Solar heating in February. After then, Oki-no-Tori Sima entered the warming up period in March because the intensifying solar energy overcame the weakening Winter Monsoon. The SST in the North-West Pacific was ready to warm up at that time and gave the initial condition of SST's in the following season. The high SST zone was also triggered to move northward at the same time. It was well described by the large scale heating of the Solar energy.
On the other hand, the summer of Japan seemingly depended on how far the high SST zone intruded in the Sea of Japan. Japan had a summer when the coastline of the northern part of Japan facing the Japan sea was surrounded by the warm water of higher than 25℃. The warm water protected that part of Japan from cooling down by the cold Othortuk High and others. The lack of the warm water happened in 1993. The year of 1993 reminded almost of the Japanese people that the cold summer attacked all of the Japanese mainland and the harvest of rice was greatly decreased. Therefore, a lot of rice was imported in order to compensate the deficit of rice.
There is a strong relation between how far the high SST zone intrudes in the Sea of Japan and when the high SST zone left Oki-no-Tori Sima. The latter could be well monitored in observing the air and sea temperature at Oki-no-Tori Sima. This fact might allow us to predict the near future state of summer in Japan in April as Trenbirth (1994) pointed out that the change in Tropical Pacific SST's lead SST's in the mid-latitude of the North Pacific by three months. The above discussion was only qualitative and preliminary. The further discussion must be required for the future work.
Acknowledgment
The data of sea temperature at Oki-no-Tori Sima was offered by the courtesy of the Hydrographic Department of the Marine Safety Agency. The SST's in the North-West Pacific Ocean and others were offered by the Japan Meteorological Agency. We express a special thanks to both organizations.
References
Sato, S. (1994):Tidal Observation at Oki-no-Tori Sima, Report of Hydrographic Researches, 30, 49-60
Trenberth, K. E. and J. W. Hurrell (1994):Decadal atmosphere-ocean variations in the Pacific, Climate Dynamics, 9. 303-319
