Abstract
Farmers in the indigenous Andean community of Cañar, Ecuador rely on an
abundant wet season each growing year and are concerned that their wet
seasons are becoming less rainy. The normal seasonal rainfall pattern in
this region, the Andes of southern Ecuador, is driven primarily by the
seasonal migration of the Intertropical Convergence Zone (ITCZ).
Existing scientific literature suggests that the ITCZ’s seasonal
migration pattern could be affected by anthropogenic climate change,
thereby impacting the seasonal precipitation in the region. This study
explores the possibility that the ITCZ’s migration pattern has already
changed, which would validate the concerns of the Cañari people. This is
accomplished by tracking the movement of the ITCZ over the past few
decades using Outgoing Longwave Radiation (OLR) data. No obvious trend
in the seasonal mean position of the ITCZ has been detected. However,
OLR maps indicate an abnormal ITCZ signature during strong warm phases
of the El Niño-Southern Oscillation (ENSO), consistent with previous
studies. The interannual variability in the region’s seasonal
precipitation is also associated with varying phases of ENSO. An
additional component of this study is the development of a statistical
model using ENSO indices as input, among other atmospheric indices, to
provide seasonal precipitation forecasts for the tropical Andean wet
season each year. Besides ENSO, another potentially useful index for
seasonal prediction is the phase of the Quasi-Biennial Oscillation,
which has been linked to precipitation variability in the tropics. The
seasonal forecasting model is expected to help Ecuadorian highland
farmers decide which of their crops to plant each year, based on the
water needs of each crop.