SPECTRAL CHARACTERISTICS OF LOW-LATITUDE AURORAS OBSERVED FROM JAPAN ON FEBRUARY 11, 1958 AND ON MAY 10, 1992

Spectral characteristics of auroral displays seen from Japan are discu ssed. A spatially extended low-latitude aurora of February 11, 1958, s howed three spectroscopic components having different energy sources; (1) the ''central part excitation'' of the red doublet of [01]6300 ang strom and 6364 angstrom, which is caused by low energy secondary elect rons, (2) the ''high-latitude auroral display'' of [01] 5577 angstrom and N2+1N3914 angstrom lines which is a counterpart of a typical high- latitude aurora, and (3) the ''enhanced-airglow'' of the N2+1N3914 ang strom lines which is caused by the diffused energy loss process of pre cipitating energetic particles. A weak photographic auroral display wh ich was observed in the northern region of Japan on May 10, 1992 also showed similar spectral characteristics to those of the extended event . This suggests that weak auroral events observed from Japan were prod uced by excitation due to low-energy electrons and the direct excitati on due to incoming particles.