Structure, variability, and origin of the low-latitude nightglow continuum between 300 and 1,800 nm

The Earth's nighttime radiation in the range from the near-UV to the near-IR mainly originates between 75 and 105 km and consists of lines of different species, which are important indicators of the chemistry and dynamics at these altitudes. Based on astronomical spectra, we have characterised the structure and variability of a pseudo-continuum of a high number of faint lines and discovered a new emission process in the near-IR. By means of simulations, we identified HO2 as the likely emitter

Atomic Oxygen Retrieved From the SABER 2.0- and 1.6-μm Radiances Using New First-Principles Nighttime OH( v ) Model

The recently discovered fast, multiquantum OH(v)+O(³P) vibrational‐to‐electronic relaxation mechanism provided new insight into the OH(v) Meinel band nighttime emission formation. Using a new detailed OH(v) model and novel retrieval algorithm, we obtained O(³P) densities in the nighttime mesosphere and lower thermosphere (MLT) from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) 2.0‐ and 1.6‐μm radiances. We demonstrate how critical the new OH(v) relaxation mechanism is in the estimation of the abundance of O(³P) in the nighttime MLT. Furthermore, the inclusion of this mechanism enables us to reconcile historically large discrepancies with O(³P) results in the MLT obtained with different physical models and retrieval techniques from WIND Imaging Interferometer, Optical Spectrograph and Infrared Imager System, and Scanning Imaging Absorption Spectrometer for Atmospheric Chartography observations of other airglow emissions. Whereas previous SABER O(³P) densities were up to 60% higher compared to other measurements the new retrievals agree with them within the range (±25%) of retrieval uncertainties. We also elaborate on the implications of this outcome for the aeronomy and energy budget of the MLT region