Stratospheric Circulation Simulation

This research looks at transport of chemical constituents in the lower
stratosphere.Almost all air enters the stratosphere over the tropics. A slow,
mean vertical circulation, called the Brewer-Dobson circulation, lofts air over
the tropics from the troposphere into the stratosphere. Air lofted into the
stratosphere then moves either to the north or the south where it drops back
down to the troposphere, completing the circulation by moving back towards the
tropics.

A second, faster, horizontal circulation is active in the stratosphere. This
stratospheric circulation moves from east to west around the equator and
changes directions to west-to-east towards the poles. The net result is that
particles transported out of the tropics may cover the globe in only two months
time.