Influence of the “Tropical Pump” on Trace Constituents and Temperature
Suppose that there is a trace constituent that is stratified vertically and is initially at rest with constant mixing ratio surfaces corresponding to horizontal surfaces. When we “turn on” a meridional mass circulation with upward motion at low latitudes and downward motion at high latitudes, the effect would be to push the constituent upward at low latitudes and downward at high latitudes, so that the mixing ratio surfaces become tilted (Fig. 1). Breaking planetary waves in the stratosphere will produce irreversible mixing of the tracer along isentropic surfaces. This mixing will tend to flatten the surfaces of the constant mixing ratio. Thus, mixing competes with the effects of the diabatic circulation. Mixing, however, is a local process, occurring in the region of wave breaking, while the diabatic circulation is a global scale process.
KeywordsVorticity Advection Boris Folk
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