https://cdn.earthdata.nasa.gov/conduit/upload/5182/KeywordsCommunityGuide_Baseline_v1_SIGNED_FINAL.pdf 23.6 2026-03-19T10:41:57.720Z https://gcmd.earthdata.nasa.gov/KeywordViewer/scheme/sciencekeywords/cac28264-0788-49a9-bb6a-c2251b0b325c TOTAL ELECTRON CONTENT Total electron content is the total vertically integrated numberof electrons per unit surface area on the earth. In standard metricunits this is 10E16 electrons/m^2 also known as a TEC unit or TECU.