394 NEWELL AND MILLER crude measurements of a trace substance, ozone, and was substantiated by '8°w measurements.?? In the lower stratosphere there is cooling where the air is warm at middle latitudes and heating where it is cold at low latitudes; this leads to a destruction of available potential energy. The loss must be made up from the available potential energy of the eddies, which in turn comes from kinetic energy. The ultimate source of this kinetic energy must be outside the stratosphere. A survey of the energy generated layer by layer indicates that the driving energy for the lower stratosphere must come from the troposphere. . Above 25 km and up to about 50 km, there is cooling in the cold higher latitudes in the winter and maximum warming near the summer pole. This heating configuration obviously again implies a generation of available potential energy, and here the heat-engine region effectively stretches from pole to pole. Above this, as has been discussed elsewhere, there is an additional refrigeration that receives its driving energy from the 25- to 50-km region. For the higher level systems, it appears that in winter large-scale eddies are of most importance in the momentum budget and, by inference, the heat budget of middle and high latitudes, whereas in summer and at low latitudes the observations are not-yet sufficient to decide the relative importance of mean and eddy motions. °''® Approximate numerical values of the generation of zonal available potential energy, together with the zonal available potential energy and kinetic energy layer by layer, are shown in Table 1. A more detailed picture of the conversion of zonal available potential energy to eddy available potential energy is shown in Fig. 1. This is based on our International Geophysical Year (IGY) stratospheric data'® matched to the wind and temperature data analyzed by Buch?® and Peixoto.'* The large negative regions in the troposphere represent Table 1— DISTRIBUTION OF GENERATION OF ZONAL AVAILABLE POTENTIAL ENERGY, G,, ZONAL AVAILABLE POTENTIAL ENERGY, Az, AND KINETIC ENERGY OF ZONAL FLOW, K,, WITH HEIGHT FOR ZONE FROM 20 TO 60°N, WINTER* Layer, km G,, ergs/cm?/sec A,, ergs/cm? K,, ergs/em? 10 15 20 25 to to to to 15 20 25 30 ~—2.9 —117 1.9 4.4 11 60 0.3 0.8 x x x x 108 108 108 108 460 120 6.5 8.5 x x x x 108 108 108 108 30 40 50 60 70 to to to to to 40 50 60 70 80 6.9 2.7 0.29 —0.65 —0.15 3.1 11 0.07 0.9 1.1 x x x x x 108 105 105 105 104 22 153 71 24 6.1 x x x x x 108 105 105 105 105 *Details of the computational procedure can be found in Ref. 9.