Nitric Oxide Produced by Energetic Electron Precipitation During a Geomagnetic Storm in April 2010

Abstract:

In April 2010 a relativistic electron precipitation (REP) event occurred. A coronal mass ejection (CME) caused the Dst-index to reach -80nT, followed by solar wind speeds of over 600 km/s lasting for three days. Electron fluxes measured by the NOAA POES satellites were increased by an order of magnitude and stayed elevated for three days. We investigate the atmospheric nitric oxide (NO) response to these incoming energetic electrons. By combining the low and medium energy electron fluxes from the Total Energy Detector (TED) and Medium Energy Proton and Electron Detector (MEPED) on the NOAA POES satellites we get a continuous energy spectrum ranging from 1-1100 keV, which corresponds to atmospheric altitudes of 50-150km. The multiple NOAA satellites enables us to construct global maps of the precipitating electrons. The energy spectra of the incoming electron fluxes are compared to NO measurements from The Solar Occultation for Ice Experiment (SOFIE) on board the Aeronomy of Ice in the Mesosphere (AIM) satellite and NO from Sub-Millimeter Radiometer (SMR) on the Odin satellite. The correlation between the incoming electrons and the increase of NO is strongly affected by NO's long lifetime when not exposed to sunlight. Winds from Whole Atmosphere Community Climate Model (WACCM) and the empirical wind model HWM07 are used to take into account the transport of NO in order to understand the total impact of the incoming electrons.