Meteorology and Atmospheric Physics

, Volume 61, Issue 3–4, pp 187–199 | Cite as

Topography and the dynamical response to easterly flow in Southern Hemisphere subtropical West Coast regions

  • C. J. C. Reason


The response of the coastal atmosphere in subtropical Western Australia and south-western Africa to easterly flow is considered. Easterly flow, arising from the ridging of a large scale anticyclone near the southern extremity of these land-masses, is a common synoptic pattern, particularly during the summer half of the year. Despite similar synoptic forcing, coastline orientation and latitude, there are significant differences in the response. In Western Australia, the typical response to this easterly flow is a synoptic, non-propagating feature (the West Coast Trough) which may be located on- or offshore. The response in southern Africa is typically a mesoscale, propagating feature (the coastal low) which is trapped against the coastal mountains.

It is argued that the steep coastal mountain ranges (about 1 km height) in southern Africa compared to the gentle, low-lying Western Australian topography combined with the mean coastal stratification contribute significantly towards the differences between the coastal low and West Coast Trough. A secondary feature associated with the regional topography is the existence of an oceanic throughflow north of Western Australia from the western equatorial Pacific Ocean with associated flow of the warm Leeuwin Current polewards along the Western Australian coast. It is suggested that this current and the associated lack of coastal upwelling may play a role in the location and intensity of the West Coast Trough.


Coastal Upwelling Equatorial Pacific Ocean Summer Half Synoptic Pattern Coastal Mountain 
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Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • C. J. C. Reason
    • 1
  1. 1.School of Earth SciencesUniversity of MelbourneParkvilleAustralia

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