ISSI International Team Project #448
A research team brought together by ISSI has made significant strides in solving a key question in space physics: how ultra-low frequency (ULF) waves generated in Earth’s foreshock region transmit into the magnetosphere, influencing space weather around our planet.
Starting in their first team meeting at ISSI in Bern in May 2019, ISSI International Team #448, led by Dr. Lucile Turc and co-led by Dr. Minna Palmroth, investigated how these “30-second waves” generated upstream of Earth’s bow shock propagate across the magnetosheath—the region between the bow shock and magnetosphere—and reach the inner magnetosphere. These waves have long been suspected to play a role in magnetospheric Pc3 wave activity (waves with 10-45 second periods). However, the exact mechanisms of their transmission remained unclear.
Using advanced global simulations with the Vlasiator model, the team made a breakthrough. Contrary to earlier theories, they found that instead of directly transmitting through the bow shock, foreshock waves modulate the shock’s properties, causing fast-mode pulses to form in the magnetosheath. These pulses, generated at the same frequency as the foreshock waves, propagate earthward towards the magnetosphere. Ultimately, this discovery solved the puzzle of how these waves enter the magnetosphere, providing crucial insights into their impact on space weather processes.
In addition to this, the team explored how solar wind conditions, especially during magnetic storms, influence wave transmission. Their case study of a magnetic cloud event on July 20, 2016, confirmed that enhanced solar wind conditions significantly alter wave properties, such as frequency and amplitude, and affect their transmission into the magnetosphere.
The team’s findings resulted in three major publications, and their work paves the way for future research into how ULF waves influence the dynamics of near-Earth space. The success of this project was made possible by ISSI’s collaborative framework, which brought together experts in foreshock physics, magnetospheric studies, and advanced simulations to tackle this complex problem.
Read more on the ISSI International Team #448 Webpage.
Overview of the generation and transmission of foreshock waves in near-Earth space (Turc et al., submitted to Space Science Reviews).
