Impact of the 2015 Godzilla El Niño event on the Indonesian rainfall

Abstract

The impacts of El Niño events on the Indonesian rainfall have been documented by several earlier studies. This paper is aimed to extend the study on the El Niño impact by investigating the 2015 El Niño event, which was labelled as a “Godzilla El Niño” by NASA’s climatologist. The event is unique because of its strong intensity and it was preceded by weak 2014 El Niño. We analysed rainfall record of 87 stations for period 1981-2015 using percentile technique. The results show that during March 2015 – February 2016, the majority of stations recorded annual rainfall less than the 30th percentile, a dry condition. Based on analysis of three monthly running accumulation, we found 84%, 89% and 78% stations recording a dry condition during July-August-September (JAS), August-September-October (ASO) and September-October-November (SON), respectively. The largest impact was observed during October 2015 where 51% stations reported the rainfall below the 10th percentile, an extremely dry condition. Compared to 1997, the 2015 Godzilla El Niño event seems to have less impact on Indonesian rainfall even though the intensity of those two events is comparable. The number of stations experiencing dry and extremely dry condition was lower in 2015 than that in 1997, for all time scale we analysed. This may relate to the condition of sea surface temperature (SST) around Indonesia. We found that the Indonesian SST during June-November 2015 was warmer than that during 1997 indicating a more supporting condition for developing convective activity in 2015.