How do geomagnetic activity and solar radiation change Nitric Oxide in the lower thermosphere?

What is it about?

We use two datasets from satellites (SNOE and SOFIE) that observed NO in the lower thermosphere during the previous solar cycle (SNOE) and the current solar cycle (SOFIE). The physical processes that drive NO variations are related to geomagnetic activity and solar radiation and the geomagnetic AE index and solar Lyman-alpha index are respectively used as a proxy. By performing linear regressions on different altitudes and latitudinal regions in the NO datasets, we then are able to determine which process is dominating NO variability.

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Why is it important?

We show that geomagnetic activity controls the NO variations at polar latitudes and that it does so in the same way in both datasets, even though they are separated by nearly a decade. The effect of solar radiation is minimal in the polar regions and dominates at equatorial regions. Furthermore, even though the previous and current solar cycle are different in strength and duration, we have shown that the impact of geomagnetic activity on NO variability is independent of it.