| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2003: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
First, simple but robust approaches were used to reveal the quantitative and statistically significant influence of the Southern Oscillation Index (SOI) on monthly precipitation at five stations distributed over South Korea and Fukuoka, Japan. The monthly precipitation data were transformed into non-exceedence probability time series. SOI is classified into five categories. The spatial distribution of ENSO influence is obtained from the correlation results. The monthly precipitation in South Korea and Fukuoka, Japan is generally influenced by La Nina events. The influence has a four-month lag time in the southern coastal area, and a five-month lag for the middle to northern area of South Korea.
Second, the cross-correlations between four indices of SOI, PDOI, NPI, NAOI and normally standardized monthly precipitation in Fukuoka are investigated in detail. For the original time series, the correlations between those indices and precipitation are almost zero for any lag times. However, qui
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te strong statistically significant correlations are obtained when using those indices data categorized into five groups according to their magnitudes. In particular, very high correlation coefficients are obtained between precipitation and SOI, NPI with some lag times under some categories.
Third, a methodology to investigate joint phase space characteristics of SOI and the standardized temperature and precipitation data in Fukuoka was studied byusing ideas from dynamical systems theory. From the results, it can thus be said that the joint relationships between the three investigated variables are complex with no obvious linear relationships. The methodology may serve as a basis for deterministic dynamics of jointly interrelated variables.
Further, the medium term forecasting of August rainfall in Fukuoka city was conducted. As the candidate predictors, sea surface temperature (SST) anomalies and three atmospheric-oceanic indices are selected. It was found that a model with the NPI and selected SST as inputs performed reasonably well. Less
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