The Influence of ENSO and IOD during Mesoscale Convective Complex (MCC) to Rainfall in Indonesia

Abstract

Climate phenomena that significantly affect Indonesian rainfall to be lower (positive) and higher (negative) than normal conditions are ENSO and IOD. The other phenomenon with different time scale with ENSO and IOD is MCC that rainfall until causing storms. This study was conducted to determine the influence of ENSO and IOD during MCC to rainfall in Indonesia. The data used are monthly data of rainfall, Nino3.4-IOD index, and hourly MCC data derived from Tbb data of Himawari Satellite, year 2001-2015 observation. The study focused on 4 occurrence phenomena: Nino3.4 (+) IOD (+), Nino3.4 (-) IOD (-), Nino3.4 (+) IOD (-), and Nino3.4 (-) IOD (+) with the distribution of 3 longitude regions (90-105E, 106-125E, and 126-140E). The results showed that the distribution of rainfall during MCC were higher when the events of negative IOD compared to other events, especially in the western maritime of Sumatra until Kalimantan. While, in the Nusa Tenggara region there is no rainfall when positive Nino3.4 events due to positive ENSO influence from the Pacific Ocean. The MCC also give effect on interior cloud size and duration of life cycle when negative IOD events on 3 longitude regions. The effect includes the size of the interior of the cloud becomes larger and the duration of the life cycle is longer. Eccentricity interior is close to 1, means the contribution of MCC is high enough to Indonesian rainfall on negative IOD events.