Nitric Oxide Intensification Associated With STEVE: TIMED/SABER‐REGO Observations and Comparison With GITM Simulation

Strong Thermal Emission Velocity Enhancement (STEVE) is a nightsky optical phenomenon of great research interest in recent years. STEVE is recognized to be co‐located with a latitudinally narrow channel of fast westward ion drifts, also known as “subauroral ion drifts” (SAID). Nitric Oxide (NO) in the thermosphere has been hypothesized to intensify under SAID and play a key role in the excitation of STEVE, but definitive observations of NO variations associated with STEVE have been lacking. In this study, via a fortuitous conjunction of TIMED/SABER and STEVE, we for the first time report concrete observational evidence of NO intensification associated with STEVE. Taking into account the narrow latitudinal width of STEVE/SAID, we develop a new method to invert the STEVE‐related NO 5.3 μm volume emission rate (VER) using SABER data, and find that the NO VER within STEVE can be enhanced by more than an order of magnitude compared to the background. This result is corroborated by a pioneering GITM simulation that incorporates the effects of SAID and vibrationally excited N 2 . Based on the inverted NO 5.3 µm emission, we evaluate the NO 2 continuum intensity and compare to the observed brightness of the STEVE continuum, to make the first observation‐based reality check of the proposal that the NO 2 continuum be a candidate mechanism of the STEVE continuum. The unique observations and exploratory investigations reported in this paper shed light on the thermospheric NO dynamics and its potential role in the STEVE activity.