A numerical simulation of the Mei-Yu front and the associated low-level jet

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Author
Chou, Lang C.
Date
1986Advisor
Chang, C.P.
Williams, R.T.
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Show full item recordAbstract
The Mei-Yu front is a quasi-stationary belt of heavy
precipitation imbedded in the summer monsoon trough over
East Asia. This work used a two dimensional frontogenesis
model to study the Mei-Yu front, especially its associated
low-level jet (LLJ) which often occurs during intense
convection. Several numerical experiments were carried out
to simulate the quasi-steady frontal structures in different
environments. The results resemble many observed features,
such as the stronger temperature and moisture gradients in
the midlatitude fronts and the stronger horizontal shear and
LLJ in the subtropical fronts. The LLJ is most conspicuous
in the subtropical simulation when high humidity and surface
fluxes are included. The results further suggest that the
LLJ is developed through the Coriolis torque that is exerted
by the low-level poleward branch of a "reversed Hadley cell"
equatorward of the front. This thermally direct cell is
different from the normal cross-frontal secondary
circulation. Its development depends on the occurrence of
intense convection.