LAST UPDATE 08/12/03 2:30 p.m.
Before entering the real world, I was a graduate student and post-doctoral research scientist in the Department of Earth and Atmospheric Sciences at the the University at Albany/SUNY!
In this study, the influences of zonal variations in background flow on tropical waves are examined, with the intent of understanding wave growth that leads to tropical cyclogenesis. Two major background flow structures are considered: sign reversals of the meridional gradient of potential vorticity (PV), and regions of convergence of group velocity and thus wave accumulation. These structures are described for four major basins of tropical cyclone activity: the Atlantic, eastern Pacific, western Pacific, and Australian regions. The ideas are applied to case studies of multiple tropical cyclone formation in the western Pacific.
An additional aspect of this study is the role of equatorial mixed Rossby-gravity waves in western Pacific tropical cyclogenesis. The tropical cyclones are preceded by an amplifying mixed Rossby gravity wave packet. The active phase of the Madden-Julian oscillation is shown to play a critical role in providing the background zonal flow variations and convergence to amplify the wave packet. Over time, these waves turn away from the equator and appear to transition into Rossby-type disturbances. Tropical cyclogenesis occurs three times within consecutive cycles of these disturbances. An attempt is made to reconcile the interaction of tropical waves and the Madden-Julian oscillation with various mechanisms of wave growth and current hypotheses of western Pacific cyclogenesis.
(formerly known as ULowell).
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