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Effects of Energetic Electron and Proton Precipitations on Thermospheric Nitric Oxide Cooling During Shock-Led Interplanetary Coronal Mass Ejections
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2019
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Source: Journal of Geophysical Research: Space Physics, 124, 8125- 8137
Details:
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Journal Title:Journal of Geophysical Research: Space Physics
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NOAA Program & Office:
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Description:Satellite measurements have revealed significant enhancement of 5.3‐μm nitric oxide (NO)
emission during shock‐led interplanetary coronal mass ejections. Great discrepancies in modeled neutral
density occur during these events and may be attributed to the abnormally high NO cooling. Meanwhile, the
relative significance of protons, soft electrons, and keV‐electrons to NO emission is yet to be well determined.
The goal of this study is to identify the contribution of electron and proton precipitations to the
thermospheric NO cooling by using the Defense Meteorological Satellite Program (DMSP) data. The
observed energetic electrons and protons (0.1–30.2 keV) during 36 shock‐led interplanetary coronal mass
ejection events in 2002–2010 are binned into geomagnetic grids to provide statistical distributions of the
particle precipitation for polar regions. The distributions are incorporated into the Global
Ionosphere‐Thermosphere Model. The results show that electrons play a dominant role to NO cooling, but
protons are also important and contribute to up to a quarter of NO cooling by electrons and ions combined.
NO cooling enhancement during the events is proportional to the level of energy flux and is dominated
by the electrons in the energy band of 1.4–3.1 keV. Both total electron content (TEC) and NO cooling
enhance at the source regions, but they have different lifetime and correlation with the particle
precipitations. Generally, NO cooling and TEC enhancements have a positive correlation with the
precipitating energy. Cross correlation shows that particle precipitations have more instantaneous impact on
TEC while it takes longer for the atmosphere to heat up for cooling to proceed.
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Source:Journal of Geophysical Research: Space Physics, 124, 8125- 8137
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Rights Information:Other
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Compliance:Submitted
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