The Kp-index quantifies the electromagnetic effects in the Earth’s atmosphere and is used in a variety of scientific fields. Higher Kp values tend to be the focus in these fields as they relate to high solar activity and geomagnetic storms. This study aimed to examine the significance, if any, of lower Kp indices. A simple data analysis was performed on continuous sequences of low Kp values, deemed Quiet Periods. Both the daily average of the values and the full set of Kp data were used. A decaying exponential relationship was discovered between the length of these periods and their frequencies and then probabilities. Higher thresholds on the maximum allowed Kp value during a Quiet Period resulted in more gradual rates of decay. For the daily averages, the time constants of the probability distributions were found to be exponentially related to the threshold values. This relationship was not observed when the full data set was used. Discrepancy between the two data sets is concerning but could simply be due to a smoothing effect of averaging. The resulting probability distributions could prove useful in the prediction of Kp values.
Walbeck, Collette, "The Kp Index and Behavior of Quiet Periods" (2023). Physics Capstone Projects. Paper 105.