Global Temporal and Spatial Variations of Ionospheric Sporadic‐E Derived From Radio Occultation Measurements

Abstract

Abstract We have analyzed 13 years of radio occultation data from the first Constellation Observing System for Meteorology, Ionosphere, and Climate mission with a focus on scintillations originating in ionospheric sporadic‐E layers, henceforth referred to as Es. The analysis enabled the statistical global mapping of Es occurrence in space and time of very high resolution, and allowed an investigation of the statistical variation of Es height and thickness with seasons, solar activity, local time, and latitude. Data cleaning criteria were developed to rid the data of unreliable measurements, which allowed for more reliable statistics. To identify the Es irregularities, we applied a sophisticated algorithm termed the U‐shape algorithm that has some important advantages over other methods used on large data sets in previous studies. It is commonly known that the Es occurrence varies with the local time of day, where the greatest occurrence happens roughly around morning times and evening times. Important new observations were made in this study that show that Es height and thickness varies with seasons and solar activity, where different behavior was observed for Es in the morning and in the evening. The evening Es height and thickness showed great variations with solar activity, apparently having lower mean height and larger mean thickness when the activity is high. We interpret that as a tendency for the evening Es to be more tilted with respect to the local horizon.

Topics & Concepts