ENSO events tend to develop and mature between
austral winter (JJA) and spring (SON), peak during summer
(DJF), and decay by autumn (MAM). Rainfall over the
Maritime Continent tends to be below average in El Niño
years [Ramage, 1968] but it has been noted that the relationship
between PNG rainfall and ENSO indices is not robust
and that only very strong El Niño events appear to have a
clear impact [Allen et al., 1989; Jourdain et al., 2013]
land-sea breezes, and orography. Chang et al. [2005] used
TRMM data to demonstrate a strong relationship between
rainfall and winds over much of south-east Asia, including
West Irian.