A high‐latitude observation of sporadic sodium and sporadic <i>E</i>‐layer formation

Abstract

High‐resolution radar and lidar measurements of sporadic sodium (Na) and sporadic E ( E ) layers were made at the Sondrestrom incoherent‐scatter radar facility on 11 December 1997. These measurements suggest a causal link between E s and Na s , supporting the proposed mechanism in which Na + ions in the E s are neutralized to form the Na s . This Na s , by contrast, does not appear to have been formed by the presence of auroral precipitation or ionization, and, in fact, the sodium density is seen to decrease during an auroral event.