REFERENCES 373 



8.4.10. Conclusions 



Height-error correction can be significantly imi^roved by accounting 

 for the surface refractivity at the radar site. The use of the initial grad- 

 ient, in addition to the surface refractivity, yields a significant improve- 

 ment only for targers beyond about 60 mi and below 15,000 ft. In this 

 case, Go is important not only to improve the accuracy but to deter- 

 mine if the assumption in section 2.2 has been violated, namely, if 

 Go < — lOV^'o- The still further improvement obtained with the use of 

 AA'' would not, in general, justify the trouble and exi:)ense of measuring 

 this parameter. 



If the distance to the target exceeds about 50 mi, the normal decrease 

 with height of the gradient should be accounted for in a height error 

 correction. 



8.5. References 



[1] Bean, B. R., and G. D. Thayer (May 1959), On models of the atmospheric refrac- 

 tive index, Proc. IRE 47, No. 5, 740-755. 

 [2] Misme, P. (Nov.-Dec. 1958), Essai de radiocHmatologie d'altitude dans le nord 



de la France, Ann. Telecommun. 13, Nos. 11-12, 303-310. 

 [3] Tao, K., and K. Hirao (1960), Vertical distribution of radio refractive index in 



the medium height of the atmosphere, J. Radio Res. Lab. 7, No. 30, 85-93. 

 [4] Misme, P. (Nov.-Dec. 1960), Quelques aspects de la radio-climatologie, Ann. 



Telecommun. 15, 266. 

 [5] Bean, B. R., and G. D. Thayer (Aug. 1960), Rebuttal to P. Misme's comments on 



"Models of the Atmospheric Radio Refractive Index," Proc. IRE 48, No. 8, 



1499-1501. 

 [6] Craig, R. A., I. Katz, R. B. Montgomery, and P. J. Rubenstein (1951), Gradient 



of refractive modulus in homogeneous air, potential modulus, Book, Propaga- 

 tion of Short Radio Waves, ed. D. E. Kerr, pp. 198-199 (McGraw-Hill Book 



Co., Inc., New York, N.Y.). 

 [7] Zhevankin, S. A., and V. S. Troitskii (1959), Absorption of centimeter waves in 



the atmosphere, Radioteknika i Electronika 4, No. 1, 21-27. 

 [8] Minzner, R. A., W. S. Ripley, and T. P. Condron (1958, U.S. extension to the 



ICAO standard atmosphere, Tables and Data to 300 Standard geopotential 



kilometers, U.S. Government Printing Office, Washington, D.C. 20402. 

 [9] Ratner, B. (1945), Upper air average values of temperature, pressure, and relative 



humidity over the United States and Alaska (U.S. Weather Bureau). 

 [10] Bean, B. R., and J. D. Horn (Nov.-Dec. 1959), The radio refractive index near 



the ground, J. Res. NBS 63D (Radio Prop.), No. 3, 259-273. 

 [11] Schulkin, M. (May 1952), Average radio-ray refraction in the lower atmosphere, 



Proc. IRE 40, No. 5, 554-561. 

 [12] Bean, B. R., J. D. Horn, and A. M. Ozanich, Jr. (1900), CUmatic Charts and 



Data of the Radio Refractive Index for the United States and the World, 



NBS Mono. 22. 

 [13] W(mg, M. S. (Sept. 1958), Refraction anomalies in airborne propagation, Proc. 



IRE 46, No. 9, 1628-1639. 

 [14] Report of Factual Data from the Canterbury Project (1951), Vols. I-III, (Dept. 



of Scientific and Industrial Research, Wellington, New Zealand). 



