Grand Challenge Initiative – Cusp: observational network for solar wind-driven dynamics of the top atmosphere

This is chapter 13 of the State of Environmental Science in Svalbard (SESS) report 2019 (https://sios-svalbard.org/SESS_Issue2).

The Grand Challenge Initiative – Cusp (GCI-Cusp) is a strategic research coordination between Norway, Japan, and the US. Eight sounding rockets were successfully launched during winter 2018/19, and three more are scheduled in December 2019. Polar cusps are two funnel-shaped regions in the Earth’s magnetic field, where solar wind particles can enter the polar atmosphere. Collisions between these particles and the atmosphere produce the Northern lights. Cusp aurora is the scientific term for the Northern lights in daytime. Svalbard is a world-class laboratory for studying the cusp.

The polar atmosphere is strongly influenced by the solar wind. The GCI-Cusp questions are related to the physics of how the solar wind couples the top of the atmosphere at the poles and the effects it has: how auroral particles are accelerated by waves along magnetic field lines in the cusp, and how these energy inputs lead to heating, upwelling and outgassing of Earth’s atmospheric gasses into space. The Norwegian rocket, ICI-5, launched 26 November 2019, equipped with 12 daughter payloads for 3D imaging of turbulent vortices within the Northern lights. This turbulence sometimes causes severe disturbances/black-out of radio signals. Unfortunately, due to roll rate anomaly the daughters did not spin out. Efforts will be made to redo this novel experiment.

The initial processing of the GCI-Cusp data is ongoing and looks very promising. Some data suggest a new method of remotely detecting the cusp using VLF waves. As a world first for sounding rocket experiments, data collected within the GCI-Cusp programme will be made openly and easily available to all users through the SIOS data management system.