Electron temperature

The ratio of the flux of the auroral [O iii]λ4363 line to that of [O iii]λλ4959,5007 is sensitive to the electron temperature of the ionized gas. Based on estimates of the electron temperature and density, the oxygen abundance can be inferred from ratios of strong oxygen lines (e.g., [O iii]λλ4959,5007 and [O ii]λ3727) to Balmer lines