During this period there was an abnormal increase in the critical freqency of the F2 layer of approximately 1.3 Mc.
There was no apparent eff-
ect upon the height of the layer and no effects due to increased absorp=tion,
Rongerik:
The only significant effect was a slight stratification at the crit-
ical frequency of the F2 layer.
This effect occurred at F 4 18 min, and
CC
lasted for about 5 minutes,