Nitric Oxide Response to the April 2010 Electron Precipitation Event: UsingWACCM andWACCM-DWith andWithout Medium-Energy Electrons

TL;DR

This study uses WACCM and WACCM-D models to analyze nitric oxide production during the April 2010 geomagnetic storm, highlighting the importance of medium-energy electrons and ion chemistry for accurate atmospheric NO modeling.

Contribution

It demonstrates that incorporating a full electron energy spectrum and complex ion chemistry improves nitric oxide production modeling during geomagnetic storms.

Findings

Including medium-energy electrons enhances NO production at and below 80 km.

WACCM-D improves direct NO production but has limitations in indirect effects.

Both full energy spectrum and ion chemistry are essential for accurate NO modeling.

Abstract

Energetic electrons from the magnetosphere deposit their energy in the atmosphere and lead to production of nitric oxide (NO) in the mesosphere and lower thermosphere. We study the atmospheric NO response to a geomagnetic storm in April 2010 with WACCM (Whole Atmosphere Community Climate Model). Modeled NO is compared to observations by Solar Occultation For Ice Experiment/Aeronomy of Ice in the Mesosphere at 72-82$^{\circ}$S latitudes. We investigate the modeled NOs sensitivity to changes in energy and chemistry. The electron energy model input is either a parameterization of auroral electrons or a full range energy spectrum (1-750 keV) from National Oceanic and Atmospheric Administration/Polar Orbiting Environmental Satellites and European Organisation for the Exploitation of Meteorological Satellites/Meteorological Operational satellites. To study the importance of ion chemistry for the production of NO, WACCM-D, which has more complex ion chemistry, is used. Both standard WACCM and WACCM-D underestimate the storm time NO increase in the main production region (90-110 km), using both electron energy inputs. At and below 80 km, including medium-energy electrons ($>$30 keV) is important both for NO directly produced at this altitude region and for NO transported from other regions (indirect effect). By using WACCM-D the direct NO production is improved, while the indirect effects on NO suffer from the downward propagating deficiency above. In conclusion, both a full range energy spectrum and ion chemistry is needed throughout the mesosphere and lower thermosphere region to increase the direct and indirect contribution from electrons on NO.