Geography Reference
In-Depth Information
Fig. 11.12
Longitude-height section of the anomaly pattern associated with the tropical intraseasonal
oscillation (MJO). Reading downward the panels represent a time sequence with intervals
of about 10 days. Streamlines show the west-east circulation, wavy top line represents
the tropopause height, and bottom line represents surface pressure (with shading showing
below normal surface pressure). (After Madden, 2003; adapted from Madden and Julian,
1972.)
convergence, increased convection, warming of the troposphere, and raising of
the tropopause height. The anomaly pattern gradually moves eastward at about
5ms
−
1
and reaches maximum intensity over the western Pacific. As the anomaly
moves over the cooler waters of the central Pacific, the anomalous convection
gradually weakens, although a circulation disturbance continues eastward and can
sometimes be traced completely around the globe. The observed intraseasonal
oscillation is known to be associated with equatorial Rossby and Kelvin waves
(see Section 11.4). However, a completely satisfactory theory for the oscillation
has not yet been developed.
