Effect of Indian Ocean Dipole (IOD) Events on the Second Inter-monsoonal Rainfall in the Wet Zone of Sri Lanka

The climatic variations in the Indian Ocean have a strong relationship with rainfall anomaly of Sri Lanka. Dipole (IOD) is an ocean-atmospheric coupled phenomenon associated east-west gradient tropical Sea Surface Temperature (SST) anomalies. Identifying impact IOD on spatial and temporal variation pattern useful tool for seasonal climate forecasting. present study examined influence Second Inter-monsoon (SIM) rains Wet zone (WZ) Considering 16 rain-gauge locations scattered WZ Lanka covering nine Agro-ecological Regions (AERs), daily time series 44-years (1976-2019) were collected. IOD-positive IOD-negative years extracted based Mode Index (DMI) over neutral years. Five indices, namely, cumulative rainfall, maximum received within day, number wet days, heavy events consecutive dry days statistically analysed. results revealed significant positive mean SIM season during while this was negative (p<0.05). An apparent increase or decrease observed years, respectively. However, showed distinct events. Further investigations are suggested to elucidate El Niño Southern Oscillation (ENSO)-induced anomalous impacts.