Electron-density variations at 1000 kilometers

Data gathered at Stanford University from the Alouette satellite were separated into seasonal, diurnal, and magnetic-activity groups. Two fundamental tests of statistical significance, the χ2 test (testing the significance of the differences in the average distributions of the groups) and an analysis of variances (testing the relative variability of the groups), were applied to the data. Both tests indicated that separation of the data into the aforementioned groups was valid. Three phenomena are discussed: a significant depression of electron density at auroral latitudes under magnetically disturbed conditions, an apparent electron-density depletion over magnetic shells with a large range of L values on disturbed summer days, and a large nighttime trough centered about L = 4.