GRMB dataset: 22 years of Cluster satellite geolocalisation

2023-2024
The GRMB (Geospace Region and Magnetospheric Boundary Identification) dataset provides for the first time a classification of the four ESA Cluster satellites’ location in geospace regions from 2001 to 2022.

Beyond advancing current research, this dataset could pave the way for AI-based classification tools. The GRMB dataset is now publicly available in the ESA Cluster Science Archive.

Geospace regions: a key to understand the Earth's space environment

The terrestrial magnetised environment, or geospace, evolves dynamically due to the interactions between the Earth’s magnetic field and the interplanetary medium. Spacecraft’s coordinates alone are insufficient to determine its exact location within this complex system. An accurate classification of plasma regions and magnetospheric boundaries is essential for unambiguous studies of Earth's space environment.

Determining a spacecraft’s location in geospace is crucial for the scientific analysis and interpretation of observations. It enables scientists to identify key events such as magnetospheric boundary crossings, and to conduct statistical studies within specific regions. Additionally, such a dataset could support the development of automated region classification, serving both as training data for AI-based classification tools and as a benchmark for validating their accuracy.

Role of BIRA-IASB and first applications

The GRMB project aims to determine the location of ESA’s Cluster satellites by identifying magnetospheric regions rather than relying solely on geometric coordinates.

The GRMB project started in 2023 by BIRA-IASB in collaboration with IAP Prague. The first step of the project consisted in defining the geospace regions, their properties, and the relevant Cluster data products to identify them.

A tool has been developed to be used by human operators to manually identify the regions and their boundaries. This manual classification, based on 44 Cluster data products from multiple instruments, covers 15 labelled regions, spanning from the plasmasphere to the solar wind.

After an extensive analysis and a validation through comparisons with reference lists and automated classification methods, the GRMB dataset provides a comprehensive and continuous classification of Cluster spacecraft locations in geospace from the beginning of the mission in 2001 until 2022.

A complete description of the dataset has been accepted for publication in Nature / Scientific Data, and the first study using the dataset was published in 2024. The GRMB dataset is now publicly available in the ESA Cluster Science Archive.

Artist impression Cluster mission.
Artist impression of the Cluster mission. Credits: ESA.
Example of GRMB data
Example of GRMB data: Location of the bow shock (shock wave formed when the supersonic solar wind encounters the Earth’s magnetosphere) and location of the magnetopause (boundary between the Earth’s magnetosphere and the shocked solar wind) from the GRMB dataset for Cluster 1 in 2003. The bottom horizontal axis corresponds to the orbit number and the vertical axis to the location of the spacecraft along its orbit.
Distribution of the geospace regions crossed by each of the 4 Cluster spacecraft
Distribution of the geospace regions crossed by each of the 4 Cluster spacecraft from 2001 to 2007. The labels correspond to those of the GRMB dataset. The OUT label refers to regions located outside of the magnetosphere while the IN regions correspond to regions located inside the magnetosphere.