S-BAND RADAR ECHOES FROM SNOW 



189 



the set ami the echo source to reduce our effective range 

 considerably. Where there is no widespread rain but 

 the rain that we want to see is heavj' and concentrated, 

 the absorption of high-frequency radiation by heavy 

 rain can l^e so great that hardly any of the radiation 

 impinging on the storm makes its way back out to be 

 i-eflectcd. We could actually fail to detect a storm in 

 this way, because the storm was too intense. The fre- 

 quency we are using ( S-band) is safe against both these 

 effects, but increasing it by a factor 3 would load us well 

 into them. 



11.1.10 Ultimate Range — Greater Range 

 of a Production Set 



The performance of the prototype set we have used 

 has been specified in the previous section by its range 

 for aircraft. The performance of the same design of 

 set, constructed and installed to the final production 

 specification, is known to be better : the range for air- 

 craft is appro.ximately twice as great, and some calcula- 

 tions show that very roughly the range of a produc- 



tion set for storms will be twice that of our proto- 

 type set. 



The full account of this work is published as : Sum- 

 mer Storm Echoes on Eadar MEW, Eeport No. 18 

 of the Canadian Army Operational I?esearch Group; 

 37 Nov., 19-±4. 



n 2 S-BAND RADAR ECHOES EROM SNOW" 



Since June 1044, the Canadian Army Operational 

 Research Group has been studying the nature and ap- 

 plication of S-band radar echoes from storms. During 

 the past winter we studied echoes from snow, obtained 

 on occasions when snow was present and rain definitely 

 was not. 



Heavy snow has been detected on five occasions, 

 with maximum ranges varying from 30 to 6.3 miles. 

 One moderate snowfall wliich kept all aircraft 



''B}^ J. S. Marshall, Canadian Army Operational Research 

 Group. 



Figure 1 . Typical S-band PPI display of snow echoes. 



