ความสัมพันธ์ระหว่างปรากฏการณ์เอนโซ่และปริมาณฝนประจำฤดูกาลในพื้นที่ภาคเหนือและภาคกลางของประเทศไทย | Relationship between El Niño-Southern Oscillation and Seasonal Rainfall in Thailand’s Northern and Central Regions

Abstract

            This research investigates the existence of a correlation between the El Niño-Southern Oscillation (ENSO), in particular the Southern Oscillation Index (SOI), and the seasonal rainfall amounts along the Greater Chao Phraya River basin in the northern and central regions of Thailand. In the correlation analysis, this research utilized the monthly serial rainfall data of 1952-2014 (63 years) for the North and 1970-2014 (45 years) for the Central Plains and the 3-month running mean (3-mrm) SOI data of 1952-2014. In addition, the correlation analysis was carried out using the 3-mrm Dipole Mode Index (DMI) data of 1952-2014. The correlations between the SOI/DMI and the rainfall amounts were analyzed using the cross-lagged correlation method and verified by the t-distribution method. Furthermore, the cluster analysis was applied to the SOI/DMI-seasonal rainfall index distillation datasets to exclude the outliers and the linear regression analysis was subsequently performed to reaffirm the existence of the relationship between the index datasets and the rainfall amounts. In fact, the cross-lagged correlation results revealed that the SOI and the seasonal rainfall index are moderately correlated, with the greatest correlation coefficients of 0.21 and 0.33 for the northern and central regions; and that the correlation between the DMI and the rainfall index is inconclusive. More importantly, the SOI-rainfall correlation results confirm the SOI’s predictive ability of the seasonal rainfall and its usefulness in the operation of the country’s reservoirs and flood prevention.