Mentawai Trade Variation

While South Easterly trades are the dominant theme thoroughout Indonesia local variation can be significant around Western Sumatra, even at the same time of year. These images show the variation in September.

South Eastern trade winds are the dominant force between the equator and about -30 degrees latitude. However the interplay of scattered islands, volcanic highlands and broader climatic patterns do come into play and as you approach the equator the Intertropical convergence zone means northerly and southerly trades can come together – the region known as the doldrums.

The images below track the wind via satellite giving a monthly average for september over the past few years. 2010, 2009, 2008 and 2005 all show a variation on a circulation pattern off Western Sumatra consistent with this convergence zone that give winds in the Mentawai a light variable pattern. However in 2006, 2011 and this year so far show uninterrupted Southerly winds through the region.