Oct 3, 2012

Rainfall reductions over Southern Hemisphere semi-arid regions: the role of subtropical dry zone expansion

Wenju Cai, Tim Cowan, Marcus Thatcher
Scientific Reports
  • States that since the late 1970s, Southern Hemisphere semi-arid regions such as southern-coastal Chile, southern Africa, and southeastern Australia have experienced a drying trend in austral autumn, predominantly during April and May
  • States the rainfall reduction coincides with a poleward expansion of the tropical belt and subtropical dry zone by around 2°–3° in the same season, raising questions as to whether the regional rainfall reductions are attributable to this poleward expansion
  • Shows that the impact of the poleward subtropical dry-zone shift is not longitudinally uniform: a clear shift occurs south of Africa and across southern Australia, but there is no evidence of a poleward shift in the southern Chilean sector