Modeling of Na airglow emission and first results on the nocturnal variation at midlatitude

Abstract

A model for sodium airglow emission is developed by incorporating all the known reaction mechanisms. The neutral, ionic, and photochemical mechanisms are successfully implemented into this model. The values of reaction rate coefficients are based upon the theoretical calculations as well as from experimental observations. The densities of major species are calculated using the continuity equations, whereas for the minor, intermediating, and short‐lived species steady state approximation method is used. The modeled results are validated with the rocket, lidar, and photometer observations for a branching ratio of 0.04 for the production of Na(2P) in the reaction NaO + O → Na(2P, 2S). The inputs have been obtained from other physics‐based models and ground‐ and satellite‐based observations to give the combined volume emission rate (VER) of Na airglow between 80 and 110 km altitude. In the present study, the model is used to understand the nocturnal variation of Na VER during the solstice conditions. The model results suggest a variation of peak emission layer between 85 and 90 km during summer solstice condition, indicating a lower value of peak emission rate during summer solstice. The emission rates bear a strong correlation with the O3 density during summer solstice, whereas the magnitude of VER follows the Na density during winter solstice. The altitude of peak VER shows an upward shift of 5 km during winter solstice.

Impact of M‐solar flare‐induced solar proton event on mesospheric Na layer over Utah (41.8°N,112°W)

“…It would be worth mentioning here that neutral and ion chemistry are the dominating sources for the production of Na concentration below and above the peak density layer (∼90 km) [Plane et al, 2015;Dawkins et al, 2016;Bag et al, 2015]. Here we have considered only the neutral chemistry as discussed above.…”

“…The mesosphere-lower thermosphere (MLT) is a source region for the meteoric metal layers. Among all the meteoric metals, sodium is extensively studied due to the fact that its large scattering cross section makes it a good tracer for thermal and dynamical states of MLT region [Plane et al, 2015;Bag et al, 2015]. There are many sources for the production of sodium but the dominating one is reaction with ozone concentration [Plane, 1991].…”

On the relationship between the mesospheric sodium layer and the meteoric input function

“…A typical sodium chemistry scheme consists of neutral chemistry, ion chemistry and photolysis. The sodium chemistry research in recent years has primarily been based on the sodium chemistry model by Plane (2004), which has been cited in various subsequent works, including Bag et al (2015) and references therein.…”

On the relationship between the mesospheric sodium layer and the meteoric input function

“…A typical sodium chemistry scheme consists of neural chemistry, ion chemistry, and photolysis. The sodium chemistry research in recent years has primarily been based on the sodium chemistry model by Plane (2004), which has been cited in various subsequent works, including Bag et al (2015) and references therein.…”