East Asia and Western Pacific METEOROLOGY AND CLIMATE

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4) Cumulus vertical flux of heat (the 7-th term on the
right hand side of FIq,(2})
Based on the parameterization scheme proposed by
Schneider and Lindzen (1976) , this term may be further
rewrithen as follows:
He is the dimensionless cumulus mass flux which is a
crucial, parameter to determine the cumulus mixing.
Fig. 2 is the secondary circulation forced by this
r.firm. There is a complete positive circulation in the
ant-ire domain, with the center located at 300 km and 500
hPa .
x 100 hPa
7 r'
Fig.-2 The secondary circulation forced to 1 cumulus vertical
flux of heat (the interval of ^ is 0.4*10*).
5)Comparison among various thermal forcing terms
The intercomparison of various forcing terms has
Indicated that, for the thermal forcing of the. secondary
circulation of typhoons the horizontal turbulent flux of
heat, is insignificant; the vertical turbulent flux, of heat
is relatively large; the cumulus horizontal flux of heat is
relatively small,
only with the same order of magnitude as
the horizontal turbulent flux of heat, while the cumulus
vertical flux of heat is more significant, with the order
of magnitude of 10~*and the rather complete circulation
ceii.. • • . , '. . . .- . . ' , • . • • . . . ' ;. , . •. . . . . •••. •
The di.abatic heating is the primary forcing factor
among them. with the order of magnitude of the secondary
circulation being 10"*and a greater magnitude of than that
for cumulus vertical flux of heat. This vigorous positive
circulation dominates nearly the entire domain under study.
Fig. 3 is the secondary circulation forced by all the
thermal forcing terms (including the above five
factors).showing features similar to Fig. 1. A positive
rircul at.ion dominates the entire domain with a weak
negative circulation at low level in the outer region of