Nitric Oxide Concentration: A New Data Set Derived From SABER Measurements

Abstract

Vertical profiles of nitric oxide (NO) concentration are derived between 120 and 250 km using updated NO emission rates measured by Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. The Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar (MSIS) 2.1 model is used to provide the required parameters of temperature, atomic oxygen number density, and molecule oxygen number density needed to derive the NO concentrations using a non‐local thermodynamic equilibrium (non‐LTE) model. The SABER NO concentration shows a significant correlation with solar activity with larger peak NO concentrations and higher altitude extent during solar maximum years compared to those during the solar minimum years. The SABER NO agrees well with the MSIS 2.1 NO at altitudes above 120 km for all latitudes, while the pronounced SABER‐MSIS NO discrepancy below 120 km is likely due to the temperature underestimation by MSIS 2.1. A detailed error analysis is presented and considers systematic and random errors in all the terms in the non‐LTE model used to derive the NO concentration. Random error in MSIS 2.1 temperature and atomic oxygen dominates the uncertainty in single NO profiles above 120 km. We estimated a systematic error up to ∼36% between 120 and 250 km during solar maximum years.

Infrared Radiation in the Thermosphere From 2002 to 2023

“…These two emissions are the dominant mechanisms of thermospheric radiative cooling below 250 km. The NO concentration is highly variable, and its abundance has been the object of observational efforts and modeling studies for many years (e.g., Barth, 1992;Barth et al, 2003;Dobbin & Aylward, 2008;Maeda et al, 1992;Siskind, Barth, Evans, & Roble, 1989;Wang et al, 2024). There is now also substantial interest in CO 2 as its abundance is increasing in the thermosphere with the effect of imposing a long-term cooling trend (Qian et al, 2021;Roble & Dickinson, 1989) with potential implications for space operations and the space economy (Brown et al, 2021;Mlynczak, Yue, et al, 2021).…”