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A simple model of the tropical atmosphere driven by a circulation‐dependent forcing
Author(s) -
Weare Bryan C.
Publication year - 1986
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49711247208
Subject(s) - advection , perturbation (astronomy) , humidity , forcing (mathematics) , environmental science , atmospheric sciences , climatology , mechanics , geology , meteorology , physics , thermodynamics , quantum mechanics
A linearized shallow water model is forced by a circulation‐dependent heating term. This heating is derived from a consideration of the moisture budget equation and includes terms representing vertical motion, horizontal advection and evaporation. The model is iterated to achieve steady states. The impact of various terms of the heating expression to initial surface layer specific humidity perturbations near 2.5°N and 22.5°S is explored for a hypothetical mean specific humidity field representing the tropical Pacific Ocean. The vertical motion and advection terms in the heating equation lead to a smaller scale of heating than the initial perturbation. The evaporation term tends, on the other hand, to maintain or increase the spatial scale of the heating. For the initial perturbation at 2.5°N the final heating region is often shifted westward of its original position but remains at the same latitude. The 22.5°S perturbation leads to a heating zone equatorward of the original perturbation. The possible impact of these processes on El Nino theories is briefly discussed.