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