KEYWORDS: Data modeling, Thermosphere, Mesosphere, Temperature distribution, Ozone, Chemical analysis, Atmospheric physics, Satellites, Air temperature, Ultraviolet radiation
The model of excited OH with constants corresponding to the published data was applied to retrieve nighttime distributions of О, Н, ОН, НО2, and the chemical heating rate at the altitudes of 80–100 km from the data of the SABER/TIMED measurements in 2021. The analysis revealed that the new parameters of the retrieval procedure result in significant changes in O, H, and the chemical heating rate, but not for the OH and HO2 distributions.
In this paper, the photochemical equilibrium of the odd oxygen and hydrogen families at altitudes of 50-80 km has been investigated via a three-dimensional chemistry-transport model. It is shown that there are wide enough ranges of latitudes, altitudes, and local times when the true concentration value of these families is in the ten percent vicinity of their instantaneous equilibrium values. In this case, the concentrations of these families can be considered to be in equilibrium and appropriate algebraic equations can be used to retrieve poorly measured minor mesospheric constituents, to validate measurement data, or to refine photochemical reaction constants.
The conditions for the feasibility of the daytime photochemical equilibrium approximation of the odd oxygen (Ox) and hydrogen (HOx) families at altitudes of 50-80 km has been investigated with the use of analytical analysis and a onedimensional model. We proposed the criteria of their equilibrium. It’s shown that when the criterion is limited to 0.1, the difference between the true values of the concentrations of Ox and HOx and their local equilibrium values is approximately 10%. In this case, one can consider their concentrations to be in an equilibrium and use corresponding algebraic equations in different practical applications.
The revised model of excited OH with constants corresponding to the published data was applied to retrieve daytime O and H distributions at 77 km–100 km from the data of the SABER/TIMED satellite measurements in 2002–2021. It was found that changes of parameters in the retrieved procedure lead to (1) a noticeable (up to 30%) increase of the O concentration below 85-86 km, (2) a significant (up to 170%) increase of the H concentration below 90 km and a moderate (up to 40%) decrease near 100 km. The influence of revised O and H data on the retrieval of OH and HO2 is also analyzed.
The feasibility of the daytime photochemical equilibrium of families of the odd oxygen and hydrogen at the altitudes of 50-80 km has been investigated via a one-dimensional model. It’s shown that if the permissible alterations between true values of the concentrations of these families and their instant-equilibrium values are limited to 10%, there are quite wide ranges of heights and local times in which we can consider the concentrations of these families to be in an equilibrium and use suitable algebraic equations to retrieve poorly measured minor constituents of mesosphere, validate measured data or refine constants of photochemical reactions.
On the example of the SABER/TIMED satellite data measured in 2003, we analyze the quality of daytime O and H retrieval at the altitudes of the mesosphere - lower thermosphere with the use of the condition of ozone photochemical equilibrium, which takes into account only the main chemical sink of this component due to photodissociation. It is shown that neglecting the reaction H+O3→O2+OH in this condition weakly manifests itself in the H distributions, but leads to a significant (up to 50-70%) systematic underestimation of the monthly mean and annually mean O distributions at the altitudes of 75-90 km.
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