Advances in Space Weather Data Interpretation and Simulations

Abstract

This editorial highlights recent data and model results for Space Weather readers. One of the ways that American Geophysical Union (AGU) features some of the most interesting journal articles is Editors' Highlights. As of late 2017 these are now hosted on the Eos website: https://eos.org/editor-highlights, giving them new prominence. Editors contribute a short summary of the highlighted article in language that will appeal to general Eos readers and include a “teaser” line and visually attractive figure from the manuscript. Doing so helps to share scientific content beyond a journal's readership to a broader audience. However, occasionally a situation arises, wherein an Editor sees a manuscript worthy of additional notoriety, but the summary simply needs more technical wording than might be appropriate for general readers. Below, I am highlighting two such manuscripts that illustrate advances in Space Weather (SWE). Based on analysis of total electron content estimated from Global Positioning System (GPS) and Defense Meteorological Satellite Program spacecraft measurements, Katamzi-Joseph et al. (2017) report the occurrence of ionospheric depletions (plasma bubbles) at anomalously high, European latitudes (42°N geographic) during two intense geomagnetic storms in 2000 and 2001. Somewhat counterintuitively, such depletions may develop in the postsunset sector where plasma density has been previously enhanced. GPS signals often scintillate passing through these bubbles. The authors suggest that conditions supporting rapid upward plasma drift near the equator can extend to the midlatitude ionosphere during storm time, making these regions susceptible to navigation signal scintillation during intense geomagnetic storms. They estimate a maximum apex height of the postsunset plasma depletions as ~4,000 km. The data for the two intense storms show that the evening enhancement of the equatorial ionization anomaly extended to middle-latitude Europe during the time of the plasma bubble occurrence. The authors propose an eastward penetrating electric field-associated with the interplanetary Bz southward turning as a possible mechanism for plasma enhancement and subsequent middle-latitude plasma bubbles. Although the midlatitude ionosphere is generally considered safe from radio signal scintillation effects, this study confirms that there may be no safe zone from space-based signal scintillation during intense storms. (See Mendillo et al., 2018; Wei et al., 2015, and references, within these for previous examples and further impacts.) The Space Weather Prediction Center (SWPC) now runs subsets of the models that comprise the Space Weather Modeling Framework (SWMF). See http://www.swpc.noaa.gov/news/announcing-geospace-model-version-15. Haiducek et al. (2017) simulated a month of geospace response for January 2005 using SWMF with the University of Michigan global magnetohydrodynamic code Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme (BATS-R-US) coupled to the Rice Convection Model (RCM) inner magnetosphere and the Ridley Ionosphere Model. The interval included three large, previously simulated, and well-studied geospace storms. The authors launched the simulation three times. The first launch was with a standard 0.25 Earth radii (RE) SWMF resolution, corresponding to the operational version at SWPC. Then a higher (0.125 RE) resolution grid was applied with and without the RCM inner magnetosphere model. Various indices of geomagnetic activity (Kp, Sym-H, and AL) and the cross polar cap potential (CPCP), which is a proxy for geospace interaction with the solar wind, were calculated from the simulation and compared with observations and an empirical model that estimates CPCP. The SWMF model predicted the Sym-H (proxy for ring current) index very well. The Kp geomagnetic index and the CPCP are well predicted during storm conditions, but these indicators are overpredicted during quiet time. The model tends to underpredict the magnitude of the auroral electrojet, AL index. The Generally, the grid resolution has limited influence for the accuracy of the predictions except for auroral activity. However, the use of the inner magnetosphere model is essential. For the CPCP there is little effect from turning off the RCM. The Sym-H, AL, and Kp indexes, however, are very different when the inner magnetosphere model was turned off. This study is a significant step in showing how well one of the new SWPC models performs during storm conditions and in detailing the sensitivity in model driving. Importantly, the authors provide access to the model output for others to use. As an applications journal, SWE content covers data, model description and validation, and aspects of engineering that challenge even our technically savvy readers. So there are times when technical terms and acronyms might be problematic for a short highlight aimed at a wider readership. You can help SWE Editors promote and publicize as much content as possible by providing illustrative graphics with easy-to-follow captions and by writing plain language summaries of your manuscripts. In turn your Editors will work to highlight the best work. No data were created for this editorial.