150 



EHHALT 



50 



40 



30 



E 





20 



10 



i — i — r 



A , Rocket flight, 

 September 1968, 

 White Sands, N. Mex. 



+ , Balloon flight, 

 July 1967, 

 Palestine, Tex. 



, Tropopause 



Average Scottsbluff 

 profile- 



I I I I 



i_J I L 



J ! L 



J_ 



I I l I 



0.5 1.0 1.5 



CH 4 MIXING RATIO, ppM 



2.0 



Fig. 1 Vertical profile of the CH 4 volume mixing ratio in the stratosphere. The balloon 

 data 18 are supplemented by the results of a rocket flight which collected an integrated 

 sample at altitudes between 44 and 62 km. The weighted mean altitude 1 6 of this sample is 

 50 km. 



about 30 N. The horizontal flow of this meridional circulation is so slow that 

 the air spends about a year in the stratosphere, enough time to react the CH 4 . 



1 4 



Thus practically all CH 4 entering with the air, 0.6 X 10 g/year, is destroyed. 

 The other loss of CH 4 to the stratosphere is by upward diffusion driven by 

 the CH 4 gradient in the stratosphere (Fig. 1). The vertical diffusion flux is 



J 



3M 

 3z 



-P K z^r 



where p is the density, K z is the vertical eddy-diffusion coefficient, and 3M/3z i 

 the vertical gradient of the CH 4 mixing ratio at the tropopause. 



