Highlights

– an overview of the scientific highlights of the sessions SWR3, SWR4, SWR5 –

Iulia Chifu
Institute for Astrophysics and Geophysics,
G.-A. University of Göttingen

Animation of the deformation of the Earth’s magnetosphere under the hurdles of a a geomagnetic storm. Source: NASA’s Scientific Visualization Studio

The magnetosphere is a “natural plasma laboratory” [D. Wang, SWR3] and Earth’s shield against the solar wind, coronal mass ejections and cosmic rays from deep space. The research on the dynamics of the inner magnetosphere with its three components, the ring current, plasmasphere and the radiation belts, is very important for understanding the risks posed on the Earth-orbiting satellites and astronauts. The Earth’s layered atmosphere acts as a natural armor against some of the solar radiation. The coupling between Earth’s magnetosphere and ionosphere is of high importance for us not only because of the beautiful auroras but also because process of magnetosphere-ionosphere coupling involves the transport of vast quantities of energy and momentum [1] between the hot but diluted magnetospheric plasma and the cooler, but denser, plasma in the ionosphere [2]. “The Earth’s ionosphere, being the uppermost part of the atmosphere, is partially ionised due to the solar EUV radiation and precipitation of charged particles. It is coupled to the geospace, and auroras in the polar regions are a manifestation of this coupling. Space weather is highly variable in its nature, and so is the dynamic response of the ionosphere to geomagnetic activity. This results to gradients and irregularities in the plasma density, which can affect the propagation of trans-ionospheric radio waves, thus degrading communication and positioning services. This is one of important space weather effects” [ W. Miloch, SWR4]. For over 150 years, geomagnetic disturbances are responsible for the disruption of the telluric electrical system. [3]

The solar wind interacts with the Earth’s magnetic field to produce the auroral currents or electrojets, which on their turn produce fluctuations in the geomagnetic field (geomagnetic disturbances). In the regions near the electrojet the magnetic field variation at Earth is more pronounced. The regions of the earth that experience this time-changing magnetic field will have electric currents and associated electric potential gradients induced in the earth [4]. Various systems that use electrical conductors can be affected by the geomagnetically induced currents (GICS), like, for instance, the ones transmitting power or signals to pipelines and railway tracks, for which the conducting properties are incidental [3].

Inner Magnetospheric Dynamics and Coupling Processes

During the SWR3 session, we will learn about the dynamics of the inner magnetosphere and its coupling with the ionosphere. The conveners of the SWR4 session prepared a program with a focus on our understanding of the coupling mechanism between the Earth’s magnetosphere, ionosphere, thermosphere and the space weather impact.  By listening the talks of the SWR5 program, we will dive into the current research on the different aspects of geomagnetically induced currents (GICs). The three sessions are distributed over the entire week. You can gain more insights into the session’s presentations of SWR4 on Monday afternoon and during the morning sessions on Wednesday and Thursday, of SWR3 on Tuesday evening and Thursday afternoon and evening, and of SWR5 on Tuesday morning and evening.

One of the SWR3 scientific highlights will present advancements in the research Dedong Wang (talk on Tuesday, 05.11 at 17:30; contributed highlight text, here) pursue to answer the scientific question “Why do the Earth’s radiation belts respond differently to geomagnetic storms which have approximately the same intensity?” In the talk entitled Waves in the Inner Magnetosphere, and their Effects on Energetic Electron Dynamics D. Wang will give an overview on the  “[…] effect of different waves on the dynamics of radiation belt electrons […]”,  and he will show the improvements made on the “[…] physics-based radiation belt and ring current electron dynamic model by using most advanced wave models and calculating diffusion coefficients using more realistic background magnetic field and cold plasma density models.” The validation of the “[…] simulation results against satellite measurements to understand the competition between acceleration and loss caused by various mechanisms” is also part of his talk.   One of the satellites in preparation is the Space Weather Orbital Radiation Detector (SWORD) planned by the European Space Agency (ESA) to monitor the Earth’s radiation belts “from a wide variety of locations in the magnetosphere”. The author of the second scientific highlight of the SWR3 Melanie Heil (talk on Thursday, 07.11 at 15:00; contributed highlight text, here) will introduce us to the mission concept and current design of SWORD. 

Interactions in the Earth’s Magnetosphere-Ionosphere-Thermosphere System

The conveners of the SWR4 highlighted the scientific contribution of Karl Laundal (talk on Monday, 04.11 at 14:00; contributed highlight text, here) and Wojciech Miloch (talk on Wednesday, 06.11 at 09:00; contributed highlight text, here). K. Laundal will “introduce a new global model that captures how the ionosphere dynamically responds to both magnetospheric forcing and neutral winds”.

Figure 1. Examples of the Swarm-VIP-Dynamic models for density gradients at 100 km in the polar regions, as a function of day of year (DOY) and time (UT) compared to the actual data from Swarm (W. Miloch)

W. Miloch and collaborators will present the research of a team project which using several years of Swarm data, studies the dynamics of the ionosphere and investigates the ionosphere response to the space weather. Launched in 2013, Swarm is an ESA constellation mission for Earth Observation (EO) which survey Earth’s geomagnetic field, its temporal evolution as well as the electric field in the atmosphere (https://earth.esa.int/eogateway/missions/swarm). “The team relates the results to different ionospheric regions (i.e., polar, auroral, mid- and low latitudes) and local times, as well as to the careful selection of geophysical proxies related to forcing from above (magnetosphere) or below (thermosphere), including also the thermosphere Swarm data product for the development of models. […] Through the Swarm-VIP-Dynamic project, the team tests the operational capabilities of low Earth orbiting satellites and models based on these. […] The Swarm-VIP-Dynamic team will present the background and model concepts, challenges, initial results, their new models, and prospects for further development.”

In the presentation with the title Driving the mid-latitude ionosphere from below: Using a Radio Telescope to Observe the Terrestrial Environment, Alan Wood (talk on Wednesday, 06.11 at 09:45; contributed text, here) and collaborators will introduce us to the Space Environment and Radio Engineering (SERENE) research group which investigates the “morphology, origin and evolution of plasma structures inferred from observations made using LOFAR, and to establish the implications of these observations for Earth system science”, with a focus on processes in the midlatitude and sub-auroral ionosphere. The Low Frequency Array (LOFAR) is a radio telescope composed of 52 stations which record the radio waves in the frequency range of 10-90 MHz & 110-250 MHz and with a temporal resolution of approximately 10 ms.

The conveners of the SWR4 session would like to underline the talks of the two invited speakers, Maxime Grandin (talk on Monday, 04.11 at 14:00) and Audrey Schillings (talk on Monday, 04.11 at 14:15).  M. Gradin will give a talk on the Advances in auroral and sub-auroral research leveraging citizen science: an ARCTICS, while Audrey Schillings will present a statistical study on sub-auroral polarization streams (SAPS) associated with dB/dt spikes. 

Advancements in Geomagnetically Induced Currents (GICs)

As part of the SWR5 highlights,  Jordan Guerra and collaborators (talk on Tuesday, 05.11 at 09:15; contributed highlight text, here) will introduce the audience to the improvements and validations of the NOAA-USGS geoelectric model, which is a “collaboration between the National Ocean and Atmospheric Administration’s (NOAA) Space Weather Prediction Center and the U.S. Geological Survey’s (USGS) Geomagnetism Program, provides near-real time, gridded, induced geoelectric fields across the continental United States (CONUS)[…].”  According to the authors, the model is in use starting with 2017 and currently they perform evaluations and validations of the model such as the impact on the ground magnetic observations network, validation of calculated geomagnetic and geoelectric fields against magnetotelluric (MT) measurements, and validation of geoelectric fields against GIC measurements. The second SWR5 highlight, Craig J. Roger and co-authors (talk on Tuesday, 05.11 at 09:00; contributed highlight text, here) will give us insights into the GIC computational model which “calculates currents for all the transformers at risk from GIC (i.e., those grounded on the high voltage side)” and which “has been validated using years of Transpower GIC measurements”. Transpower New Zealand Ltd is the power grid system operator in New Zeeland.  We will learn how the validated model was used to identify “the most at risk locations” in the case of extreme geomagnetic storms. One of the presentation components most probably be also related to the observations obtained during the geomagnetic disturbance occurred in May 2024.

[1] Achilleos, N., Ray, L., & Yates , J.  (2021, August 31). Magnetosphere–Ionosphere Coupling. Oxford Research Encyclopedia of Planetary Science. Retrieved 22 Oct. 2024, from https://oxfordre.com/planetaryscience/view/10.1093/acrefore/9780190647926.001.0001/acrefore-9780190647926-e-227.

[2] Yohsuke Kamide, Wolfgang Baumjohann, Magnetosphere-Ionosphere Coupling, 1993, Springer Berlin, Heidelberg, https://doi.org/10.1007/978-3-642-50062-6

[3] D.H. Boteler, R.J. Pirjola, H. Nevanlinna, The effects of geomagnetic disturbances on electrical systems at the Earth’s surface, Advances in Space Research, Volume 22, Issue 1, 1998, Pages 17-27, ISSN 0273-1177, https://doi.org/10.1016/S0273-1177(97)01096-X.

[4] Geomagnetic disturbance effects on power systems, in IEEE Transactions on Power Delivery, vol. 8, no. 3, pp. 1206-1216, July 1993, doi: 10.1109/61.252646.