ULF Wave Modeling, Effects, and Applications: Accomplishments, Recent Advances, and Future

Abstract

Ultra Low Frequency (ULF) waves play important roles in magnetosphere-ionosphere coupling, ring current and radiation belt dynamics, and modulation of higher frequency wave modes and energetic particle precipitation. The “ULF wave modeling, effects, and applications” (UMEA) focus group - part of the Geospace Environment Modeling effort from 2016 to 2021 - sought to improve understanding of the physics of ULF waves and their specification in geospace models. Through a series of in person and virtual meetings the UMEA focus group brought modelers and experimentalists together to compare ULF wave outputs in different models, plan observation campaigns focused on ULF waves, discuss recent advances in ULF wave research, and identify unresolved ULF wave science questions. This article summarizes major discussion points and accomplishments in the UMEA focus group over the last 6 years, recent advances and their connection to Richard Thorne and Peter Gary’s significant contributions to ULF wave research, and the future of ULF wave research.

Geoeffectiveness of interplanetary shocks controlled by impact angles: past research, recent advancements, and future work

“…Interplanetary (IP) shocks are solar wind perturbations that directly trigger geomagnetic activity in the magnetosphere-ionosphere-thermosphere (MIT) system. IP shocks rapidly trigger magnetic sudden impulses in geosynchronous orbit (Wang et al, 2009), magnetotail (Huttunen et al, 2005), and on the ground (Smith et al, 1986;Echer et al, 2005;Smith et al, 2020;Hajra et al, 2020); enhance field-aligned currents (Belakhovsky et al, 2017;Kasran et al, 2019), trigger auroral substorms (Kokubun et al, 1977;Zhou and Tsurutani, 2001;Yue et al, 2010), cause dayside auroras (Zhou and Tsurutani, 1999;Tsurutani et al, 2001;Zhou et al, 2003), affect radiation belts (Schiller et al, 2016;Bhaskar et al, 2021), excite magnetospheric ultra-low frequency (ULF) waves (Kangas et al, 2001;Hartinger et al, 2022); cause geomagnetically induced currents (GICs) (Carter et al, 2015;Belakhovsky et al, 2017;Tsurutani and Hajra, 2021), ionospheric total electron content (Chen et al, 2023), and thermospheric neutral mass density enhancements that intensify satellite orbital drag (Shi et al, 2017;Oliveira and Zesta, 2019). Therefore, space weather-related effects can be observed in many regions of the MIT system.…”

Interplanetary shock data base

“…1 Shock impact angle effects on intensities and latitudinal extensions of dB/dt variations linked to enhancements of GICs (Carter et al, 2015;Oliveira et al, 2021). 2 Role of shock inclinations in controlling the triggering and wave modes of ULF waves and their interaction with magnetospheric cold plasma and wave-particle interactions (Oliveira et al, 2020;Hartinger et al, 2022). 3 Effects caused by different shock orientations on thermospheric neutral and nitric oxide molecules that control thermosphere heating and cooling affecting the subsequent satellite orbital drag in low-Earth orbit (Oliveira and Zesta, 2019;Zesta and Oliveira, 2019).…”

Detection and Energy Dissipation of ULF Waves in the Polar Ionosphere: A Case Study Using the EISCAT Radar

“…Due to the many drivers, ULF waves can occur in all magnetic local time sectors. More information, including an extensive introduction to ULF waves as well as a recent overview of outstanding questions can be found in Hartinger et al (2022) and references herein.…”

“…Driving mechanisms of ULF waves are diverse and often divided into external and internal sources with respect to the magnetosphere. External sources include the Kelvin‐Helmholtz instability (KHI) on the flanks of the magnetopause, interplanetary shocks, high solar wind speeds, or peaks in the dynamic pressure of the solar wind, while internal sources can be wave‐particle interactions from the radiation belts among others (Hartinger et al., 2022). Due to the many drivers, ULF waves can occur in all magnetic local time sectors.…”