Low‐latitude volcanic Eruptions and their effects on Sri Lankan rainfall during the north‐east monsoon

Abstract

AbstractRecent studies have pointed out the modification of climate by aerosols released in the stratosphere by strong volcanic eruptions. The rainfall at 15 meteorological stations in Sri Lanka and the low latitude (20° N to 20° S) volcanoes, having volcanic explosivity index (VEI) 4 or more, for a period of 112 years (1869–1980), are investigated to examine the effects of the eruptions on the rainfall activity over Sri Lanka during the north‐east monsoon season (November and December). The present study has suggested deficient rainfall in 14 out of 15 Sri Lankan stations during both the first and the first two successive north‐east monsoon seasons, which followed 53 to 80 per cent of volcanic eruption years. Also 53 to 100 per cent of the stations received deficient rainfall during both the first and the first two successive north‐east monsoon seasons following 12 out of 20 volcanic eruption years. Occurrence of deficient rainfall to the north of the inter tropical convergence zone (ITCZ) over Sri Lanka after the eruptions of the low‐latitude volcanoes could be attributed to the southward shift of the ITCZ due to depletion of the solar radiation caused by the aerosols released in the stratosphere by the strong volcanic eruptions.