An Introduction to Walker-type Circulation
(for the beginner)
University of Alaska Fairbanks
circulation cells in the atmosphere are thermally direct, ageostrophic, circulations.
The term thermally direct is used because the circulation consists
of warm air rising and cool air sinking. The exsistence of Walker-type
circulations is largely confined to the tropics where coriolis forces are
small, and ageosptrophic, or irrotational, flows can occur. These overturning
circulations are large scale and can be associated with global climate
variations. Hence, understanding Walker-type
circulations is important for predicting future climate changes.
The nomenclature, Walker-type, is young in
the field of atmospheric sciences and is used to depict circulations which
are similar to the Walker Cell (i.e.
a thermally direct cell). However,
Walker-type is generally used to refer to east-west thermally direct
atmospheric circulation cells, whereas north-south circulations are generally
combined into a Mean Meridional Circulation
(MMC) or Hadley Cell.
© Kara Sterling, 2003
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last updated 12/10/03