Global Sporadic‐E Occurrence Rate Climatology Using GPS Radio Occultation and Ionosonde Data.

An updated global climatology of blanketing sporadic E (Es) is developed from a combined data set of Global Positioning System (GPS) radio occultation (RO) and ground‐based ionosonde soundings over the period of September 2006–January 2019. A total of 46 sites and 3.2 million total soundings from the Global Ionosphere Radio Observatory network in combination with 3.0 million occultations from the Constellation Observing System for Meteorology, Ionosphere, and Climate constellation are used to calculate global occurrence rates (ORs) for two blanketing frequency thresholds: all blanketing sporadic‐E with no limit on intensity (all‐Es) and moderate‐Es with fbEs ≥ 3 MHz. Following the GPS‐RO to ionosonde comparison by Carmona et al. (2022), https://doi.org/10.3390/rs14030581 the all‐Es rates are calculated using ionosonde data and an amplitude‐based S4 threshold for the GPS‐RO data while the moderate‐Es rates use a primarily phase‐based technique. Occurrence rates are separated by intensity, season, month, and solar local time for quiet geomagnetic conditions. Overall, the general geomagnetic trends agree with previous Es climatologies and the ORs peak near 50% for all‐Es and 25% for moderate‐Es measured in the mid‐latitudes during local summer in the late afternoon. Low ORs are observed near the South Atlantic Anomaly and North America, and a general asymmetry is observed between hemispheres with higher ORs in the Northern Hemisphere. High‐latitude and late morning blanketing Es are found to be stronger but less frequent with rates nearly equal to the moderate‐Es mid‐latitude maximums. Plain Language Summary: A global climatology for sporadic‐E occurrence is developed using a combination of GPS radio occultation and ionosonde measurements for two intensity thresholds. The global OR trends generally follow the results of many previous studies with peaks in the mid‐latitudes of the local summer hemisphere during late afternoon. However, the OR magnitudes differ from previous studies as the inclusion of ionosonde data provides a "ground‐truth" to determine the best Global positioning satellite radio occultation technique for a given intensity threshold. From this, peak occurrence rates of nearly 50% are observed for sporadic‐E with no lower limit on intensity, and 25% for moderate intensity blanketing sporadic‐E. Key Points: An updated global sporadic‐E climatology is presented for two intensity thresholds using a combination of global positioning satellite radio occultation and ionosonde observationsPeak rates of 50% for blanketing Es with no intensity threshold and 25% for moderate‐Es are observed in mid‐latitudes during local summerGlobal trends are similar for both thresholds with high‐latitude sporadic‐E shown to be stronger but less frequent [ABSTRACT FROM AUTHOR]