Irregular variations in the global distribution of total electron content

The day-to-day variability of daytime total electron content (TEC) at several locations is compared to that at the mid-latitude station Hamilton for quiet as well as disturbed days in 1969. It is noticed that all these changes are seldom parallel. Sometimes, large north-south gradients are noticed, while at other times, TEC seems to pile up on either side (latitudinally) of Hamilton. On some occasions, TEC at the southern hemisphere mid-latitude is smaller than that at Hamilton for several consecutive days. It is concluded that TEC changes, at different latitudes, are neither parallel nor antiparallel in any consistent way, and large-scale random movements and/or long-lasting TEC changes, probably due to height variations, are indicated. If these are due to neutral winds, large-scale vagaries of neutral winds during quiet as well as disturbed periods (but more so during the latter) are indicated.