Rocket measurements of oxygen and nitrogen emissions in the aurora

Altitude distributions of electronically excited atoms and molecules of oxygen and nitrogen in the aurora have been obtained by means of rocket-borne wavelength scanning interference filter photometers launched from Fort Churchill, Manitoba (58.4°N, 94.1°W) on January 23, 1974. Atomic oxygen densities derived from mass spectrometer measurements obtained during the flight are used in conjunction with the volume emission rate ratio of the N₂( C³Π_u- B³Π_g) (0-0) second positive and N₂( A³Σ_u⁺, v = 1- X¹Σ_g⁺) Vegard-Kaplan bands to derive a rate constant for quenching of the N₂( A³Σ_u⁺, v = 1) level with O( ³P) of 1.7(±0.8) × 10 ^-11 cm ³ s ^-1 These data, together with O den derived from the O ₂( b¹Σ _g⁺) state nightglow emission observed during the rocket ascent, suggest that quenching of the N₂( A³Σ_u⁺, v = 1) level by O ₂ has a significant positive temperature dependence. The processes involved in the production and loss of the N ₂( A³Σ _u⁺) state are considered and energy transfer from the N ₂( A³Σ _u⁺) state to O( ³P) is found to be a significant source of the OI 5577 Å green line in this aurora at altitudes below 130 km. Emission from the NO( A²Σ⁺- X²Π) gamma bands was not detected, an observation which is consistent with the mass spectrometer data obtained during the flight indicating that the NO density was <10 ⁸ cm ³ at 110 km. On the basis of previous rocket and satellite measurements of the NO gamma bands, energy transfer from the N ₂( A³Σ _u⁺) state to NO( X²Π) is shown to be an insignificant source of the gamma bands in aurora. Altitude profiles of the N₂( a¹Π_g- X¹Σ_g⁺) Lyman-Birge-Hopfield band system are presented.