RADAR PROPAGATION FORECASTING 



115 



Figure 6. SCR-584, Winter Garden, night of March 5 

 to 6, 1945. Superstandard propagation occurs to the 

 nortliwest at 0100 and 0300 EWT. At 0400 EWT the 

 pattern is again standard. The line on the PPI indicates 

 true north. 



went from standard to above standard and returned to 

 standard. After midnight ranges built up rapidly and 

 held until after 0300, when they began a gradual re- 

 turn to standard, reaching that condition shortly after 

 0400. 



The M curve measured at 1900 was standard, fol- 

 lowed by those illustrated in Figure 7. Unfortunately, 

 no soundings weii. taken between 2035 and 0008, and 

 consequently the evolution of the elevated S from the 

 surface duct is not shown. We know that the surface 

 wind decreased from 4 mph at 2000 to calm at mid- 

 night, while the 1,000-ft Avind increased from 10 to 

 20 mph. The duct height and AM value were approxi- 

 mately constant from midnight to 0200, after which 

 the curve gradually approached standard. 



350 355 360 365 370 355 360 365 370 355 360 365 370 

 2035 EWT 0008 EWT 0110 EWT 



355 360 365 370 355 360 365 370 360 365 370 375 380 

 0205 EWT 0315 EWT 0402 EWT 



Figure 7. 3/ curves for night of March 5 to 0, 1945, 

 based on soundings at Leesburg AAF. 



Table 1 summarizes the weather and radar varia- 

 tions. It should be pointed out that the antenna height 

 for the P-band SCK-58S was 140 ft above the sound- 

 ing site, for the S-band SCE-584 the same height as 

 the sounding site. Thus at 2100 we have a 200-ft sur- 

 face duct trapping the SCE-584, but not trapping the 



Table 1. Radar-weather tabulation, March 5-6. 



*Ground range: 1, standard; 2, 3, 4, degrees of superre fraction. 



tM-curve types: S, standard; D, duct (simple surface trapping); G, ground-based S curve; L, elevated S curve; T^, transitional aloft. 



