Global ionospheric and thermospheric response to the 5 April 2010 geomagnetic storm: An integrated data‐model investigation

Abstract

We present a case study of the 5 April 2010 geomagnetic storm using observations and numerical simulations. The event was driven by a fast-moving coronal mass ejection and despite being a moderate storm with a minimum Dst near À50 nT, the event exhibited elevated thermospheric density and surges of traveling atmospheric disturbances (TADs) more typically seen during major storms. The Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIMEGCM) was used to assess how these features were generated and developed during the storm. The model simulations gave rise to TADs that were highly nonuniform with strong latitude and longitude/local time dependence. The TAD phase speeds ranged from 640 m/s to 780 m/s at 400 km and were~5% lower at 300 km and approximately 10-15% lower at 200 km. In the lower thermosphere around 100 km, the TAD signatures were nearly unrecognizable due to much stronger influence of upward propagating atmospheric tides. The thermosphere simulation results were compared to observations available from the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE), CHAllenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites. Comparison with GOCE data shows that the TIMEGCM reproduced the cross-track winds over the polar region very well. The model-data comparison also revealed some differences, specifically, the simulations underestimated neutral mass density in the upper thermosphere above~300 km and overestimated the storm recovery tome by 6 h. These discrepancies indicate that some heating or circulation dynamics and potentially cooling processes are not fully represented in the simulations, and also that updates to some parameterization schemes in the TIMEGCM are warranted.

Scientific challenges in thermosphere-ionosphere forecasting – conclusions from the October 2014 NASA JPL community workshop

“…All three areas (among others) were discussed at the 2014 workshop held at JPL. Simulations using the TIME-GCM model strongly suggest that conditions before the onset of a geomagnetic storm have significant influence on the storm's impact, which leads to the conclusion that terrestrial weather patterns that modulate tidal forcing of the thermosphere will influence storm-time dynamics Lu et al 2015). However, the relationship between terrestrial and space weather is not well represented in the literature at this time.…”

“…Recently, Lu et al (2015) demonstrated that the National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) could capture the salient features of thermospheric observations made during the April 5, 2010 geomagnetic disturbance. TIME-GCM driven with observationally based time-dependent ionospheric convection and auroral precipitation patterns derived from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) procedure (after Richmond & Kamide 1988;Lu et al 2015) reproduced the thermospheric winds observed by the Gravity field and steady-state Ocean Circulation Explorer (GOCE) and Challenging Minisatellite Payload (CHAMP) satellites, as well as the thermospheric densities from GOCE, CHAMP, and Gravity Recovery And Climate Experiment (GRACE) measurements. TIME-GCM runs driven by AMIE are used in the work described next as the basis for exploring the role of lower-boundary forcing in thermospheric variability during geomagnetic disturbances.…”

Upper thermospheric responses to forcing from above and below during 1–10 April 2010: Results from an ensemble of numerical simulations

“…Recently, Lu et al . [] investigated the response of the TI system to the first notable geomagnetic storm of solar cycle 24, which was triggered by an interplanetary shock that interacted with the Earth's magnetosphere at 08:27 UT on 5 April 2010. Their study included comparisons between the results of a simulation with the National Center for Atmospheric Research (NCAR) thermosphere‐ionosphere‐mesosphere‐electrodynamics general circulation model (TIME‐GCM) and thermospheric wind and density measurements made by the Gravity field and steady‐state Ocean Circulation Explorer (GOCE) satellite at ~270 km, along with density measurements from two additional low Earth orbiting satellites, the Challenging Minisatellite Payload (CHAMP) and Gravity Recovery And Climate Experiment (GRACE) satellites at ~302 km and 474 km, respectively.…”

Statistical characterization of ionosphere anomalies and their relationship to space weather events

“…Indeed, geomagnetic indices are indirect indicators of ionospheric conditions, and only very limited solar and interplanetary observations are available. At the same time, it is well known that troposphere waves can, in some cases, be the cause of ionosphere anomalies (Pedatella et al 2008;Immel et al 2009;Lu et al 2015). Alternatively, an unsupervised detection approach relies primarily on the relative frequency of occurrence of normal conditions to distinguish them from abnormal conditions.…”

“…Despite the availability of advanced first-principle based models linking solar activities to the dynamics of the thermosphere and ionosphere, the quantity of observations of the space environment is, at the moment, inadequate for calibrating the chain of models to a degree where they could be used to deliver a reliable forecast. Additionally, it is well known that anomalies in the thermosphere and ionosphere can also be triggered by troposphere waves (Pedatella et al 2008;Immel et al 2009;Lu et al 2015). It is therefore necessary to characterize statistically the connection or correlation between major space environment disturbances such as solar corona mass ejections (CMEs) or magnetosphere storms and ionosphere anomalies.…”