On a remarkable correlation between whistler-mode propagation and high-frequency northscatter

The simultaneous occurrence of whistler-mode and northscatter echoes monitored at Stanford University has been analyzed. The whistler-mode studies were made using NPG transmissions (18.6 kc/s) from Jim Creek, Washington, 1200 km north of Stanford. The north-scatter observations were made using a 12-Mc/s IGY sounder and a high-power 23.1-Mc/s radar. The geometry of F-region northscatter is such that the scattering irregularities are in the general latitude region in which the whistler-mode signals are believed to be propagating. A Pearson correlation coefficient of 93 per cent was found for the F-region and whistler-mode echoes. The percentage correlation was calculated on the basis of active or inactive nights, the quality and quantity of data being insufficient to draw significant conclusions about correlations on an hour-to-hour basis. The few times for which hourly correlations could be made further substantiate the remarkable coefficient. The important result of this analysis is the direct evidence of meter-scale field-aligned irregularities in that part of the F region through which whistler-mode signals are believed to have passed. These irregularities may be related to the field-aligned ducts that have been postulated to explain whistler-mode propagation.