Quantifying uncertainties in the quiet-time ionosphere-thermosphere
using WAM-IPE
Abstract
This study presents a data-driven approach to quantify uncertainties in
the quantities of interest (QoIs), i.e., electron density, plasma
drifts, and neutral winds, in the ionosphere-thermosphere (IT) system
due to varying solar wind parameters (drivers) during quiet conditions
(Kp$<$4) and fixed solar radiation and lower atmospheric
conditions representative of March 16th, 2013. Ensemble simulations of
the coupled Whole Atmosphere Model with Ionosphere Plasmasphere
Electrodynamics (WAM-IPE) driven by synthetic solar wind drivers
generated through a multi-channel variational autoencoder (MCVAE) model
are obtained. The means and variances of the QoIs, as well as the
sensitivities of the QoIs with respect to the drivers, are estimated by
applying the polynomial chaos expansion (PCE) technique. Our results
highlight unique features of the IT system’s uncertainty: 1) the
uncertainty of the IT system is larger during nighttime; 2) the spatial
distributions of the uncertainty for electron density and zonal drift at
fixed local times present 4 peaks in the evening sector which is
associated with the low density regions of longitude structure of
electron density; 3) the uncertainty of the equatorial electron density
is highly correlated with the uncertainty of the zonal drift, especially
in the evening sector, while it is weakly correlated with the vertical
drift. A variance-based global sensitivity analysis is further
conducted. Results suggest that the IMF Bz plays a dominant role in the
uncertainty of the electron density when IMF Bz is 0 or southward, while
the solar wind speed plays a dominant role when IMF Bz is northward.