TEC over continental US and Europe for the fall equinox and low solar flux conditions

The files contain median TEC (total electron content) values for a given geographic sector for a fall equinox and low solar flux conditions. The 10th, 25th, 75th, and 90th percentiles are also included. These median TEC values were calculated using TEC data provided by the CEDAR Madrigal database for the years 2000-2018. Median values of TEC and different percentiles were calculated for the following conditions: low solar activity (F10.7 daily index is 70 ± 5 SFU; 81‐day average F10.7 index is 70 ± 5 SFU), low geomagnetic activity (daily Ap index < 15 for the current day and previous 24 h), average or below average stratospheric planetary wave activity at 10 hPa and 60°S, and centered on 15 September with a ±15‐day window. Average level of stratospheric planetary wave activity was calculated from 40+ years of MERRA data. The Madrigal database contains 79 days that satisfy the aforementioned conditions, with data collected in 2008, 2009, and 2018. The TEC observations for the selected 79 days were then binned in 30‐min intervals, resulting in several hundred data points per each 1° longitude x ~ 1° latitude bin in areas with good data coverage. Median TEC values determined from these bins were used as a baseline that describes the “dynamically quiet” ionosphere in each geographic sector with high resolution in latitude and longitude. Different percentiles were used to describe typical quiet-time variability. The users are advised to use median TEC only in areas with sufficient number of data points (> 50) included in the median.