338 REFRACTION AND REFRACTIVE INDEX MODELS 



The A'^' component is generally effective over the first few kilometers, 

 while above 6 or 7 km altitude, the A'^" component forms the bulk of the 

 profile [1]. Thus the integral of the A^ profile with respect to height may 

 be written as: 



Ndh = I N' (Ns, h)dh-\- / N" {h + h,)dh + / 8N{h) dh, 



Jo Jh, Jo 



or. 



Ndh ^ F, (Ns, hd + F2 (K, ht) + 6F (ht) 



where 8F is the random contribution to the integral. For any particular 

 ht then 



Ndh = Fy (Ns) + F2 (hs) + dF 



or 



where 



N dh = F, (hs = 0) + Fi (A^^) - F3 (hs) + 8F (8.21) 



F3 = / N"(h + hs) dh, and F2{hs = 0) is a constant. 



It was found empirically, from integrated N{h) profiles, that 



N dh^a + biNs - hihs ^ S.E. (8.22) 



The analogy between (8.21) and (8.22) is plain (the standard error of 

 estimate of (8.22), SE, represents the standard deviation, SF, of (8.21)). 

 The results of such an empirical study are shown in figure 8.17 for the 

 CRPL Standard A'^ Profile Sample, for ht beyond the atmosphere. 



For any particular application of (8.22) at a single location, the term 

 62/1 s will be absorbed into the constant a, since hs does not vary. How- 

 ever the introduction of this term is necessary to explain the station 



