4 10
1:. ti. U'IPPhRMANK
2. K , PROFILES I N rtw BAKOTROPIC PBL
The results of numerical integrations are shown in Fig. 1 for four different
thermal stratifications ( p = +20. 0. -20, -40). The integrations have not
been carried out for larger stitbilities since an upper limit exist in the PBL for
stable stratification. i.e.. for the downward turbulent heat flux. This matter is
discussed by Wipprmann (1972). The curves in Fig. 1 represent the univcrsal profiles K , ( Z ) ohtilined with dimerent mixing-length hypotheses. 'The
I I(;. I Unkcrxiil bcrtical proliles 0 1 thr rddy diNusioil cocflicient \;trving with rhr Ihcrin;rl
striitifcsricin 11. DiNercnt mixing-length hypotheses :we used: A 0 = Applehy Ohimtctic.
I3
Hlitcknditr. 1. = Lertau. W = Wipperinann.
heavy curves (W') are the profiles obtained with hypothesis (5d); for ii
comparison, the other profiles are given also: L" with hypothesis (5a). "€3"
with (5b) arid "AO" with (5c). The differences in the results vary with the
t hernial stratification.
Two empirical formulae have been derived from these results, they art.
useful possibly Tor practical purposes:
( I 1 )
K m . nisi = 0.27 ZI,
,
AA = E., = 0
and
(12)
K,(%) = z cxp; -(.,,Z" '('4).
A, = R, = 0