Rainfall prediction based on the relationship between rainfall and El Niño Southern Oscillation (ENSO)

Abstract: El Niño-Southern Oscillation (ENSO) is a dominant mechanism of global inter-annual climate variability. In this study, the relationship of ENSO to seasonal rainfall over 139 years is described. Ranking both, the seasonal Sri Lankan rainfall and its contemporaneous ENSO index show modest but significant association in January-March, May and July-August and October-December periods. El Niño leads to wetter conditions during May, October-December and to drier conditions during January-March and July-August. Except for January-March the impacts of La Niña are inverse to that for El Niño. This relationship between rainfall and ENSO during October-December, January-March, July-August and May are statistically significant. This association can be used to predict rainfall during the planting phase and the harvesting phase of Maha (October-March), and during the harvest season of Yala (April-August). As ENSO predictions are regularly available, rainfall predictions can be provided 3-6 months in advance.

Keywords: Climate, El Niño, La Niña, Maha, Sri Lanka, Yala.

Doi: 10.4038/jnsfsr.v38i4.2652

J.Natn.Sci.Foundation Sri Lanka 2010 38 (4):249-255