7
T
r
t
T
wT
OT
399
SUMMER
25 +
_-
=
4
—
-
20
x
EIS-
4
=
10-
4
5r
-
o
0
0
J
l
10
20
T
TT
1
onl
1
30
40
50
LATITUDE, DEGREES
r
7
T
re
]
60
70
ee
T
WINTER
29
4
YS
'
tn
10 a
20
wv
HEIGHT, KM
or
NJ
Qo
ors.
OY
10 -
4
s|
|
0
—_L
1
j
L
a
——L.
L
LATITUDE, DEGREES
Fig. 2—Mean meridional velocity calculated from approximate heat
and momentum-forcing functions, cm/sec.
sphere; it will be recalled that a similar conclusion was reached from
considerations of the ozone budget. Hering and Borden™have recently
reached the same conclusion from a much more comprehensive study
of detailed ozone soundings. The role of these mean circulations in the
upper tropical troposphere and the stratospheric region immediately
above may be quite important. Their effect cannot extend very much
into
the stratosphere, however, since,
as has been noted by many
authors in relation to the '*w distributions, the center of gravity of
tracer concentrations remains in the vicinity of the equator for two
years or more.** An altitude limit of about 18 to 19 km seemsto be
indicated. We may note that similar general findings have been re-
ported over the years by Starr and Peixoto for water vapor in the