The influence of internal atmospheric variability on the ionosphere response to a geomagnetic storm

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Monday, June 18, 2018

Nicholas Pedatella notes that geomagnetic storms are an important driver of variability in Earth’s ionosphere, and can have significant societal impacts through the ionosphere’s impact on communications and navigation systems (e.g., GPS).

WACCMX simulated total electron content (TEC) image
This figure shows the change in WACCMX simulated total electron content (TEC) during a geomagnetic storm for individual ensemble members on (a-e) October 30 at 1200 UT, and (f-j) November 1 at 1200 UT. The ensemble members have arbitrarily different lower atmospheres. The figure illustrates that, although the large scale features are similar, different lower atmospheric conditions can significantly impact regional aspects of the ionospheric response to a geomagnetic storm.

Numerical simulations are a common tool for the specification and forecasting of the ionosphere variability driven by geomagnetic storms. Simulations have historically only used a climatological spectrum of waves propagating upwards from the lower atmosphere (i.e., troposphere, stratosphere, and mesosphere; 0-100 km). This neglect of the day-to-day variability of wave forcing from the lower atmosphere is a potential source of uncertainty when simulating the ionosphere variability during geomagnetic storms. The present study uses a whole atmosphere model, extending from the surface to ~500 km, to understand the uncertainty in the ionosphere response to a geomagnetic storm that is due to the day-to-day variability of the lower atmosphere. It is found that omitting lower atmosphere variability leads to an uncertainty in the ionosphere response to a geomagnetic storm that is typically ~20-40%, but can be as large as 100% regionally. Incorporating the day-to-day variability of the lower atmosphere is thus an important factor for reducing the uncertainty in numerical models that are used to specify and forecast the near-Earth space environment.

Author's Name: Nick Pedatella; Publication Name: Geophysical Research Letters

https://www2.hao.ucar.edu/sites/default/files/webform/draft02_0.pdf

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