Satellite based observation: GFZ

Satellite-based observation

LEO Satellites for Earth Observation

We employ data from Low Earth Orbit (LEO) satellites to observe and gain a deeper understanding of our planet and its near-space environment, particularly the Earth's magnetic field, the ionosphere, and the thermosphere. This data is critical for analyzing how these systems are affected by solar activity and various processes occurring within the Earth's interior. We have worked and continue working with data from dedicated magnetic satellite missions, developing scientific products, creating data processing algorithms, contributing to calibration and validation activities, and supporting mission design. GFZ scientists have been part of the proposing teams for key missions such as CHAMP (German magnetic field mission managed by GFZ) and Swarm (ESA's magnetic field mission). Our roles have varied across missions from concept development and payload design to long-term data analysis and product delivery, helping to advance global magnetic field modelling and our understanding of near-Earth space.

LEO satellite altitudes 2025 — Satellite altitude over time for CHAMP, GRACE, GOCE, GRACE-FO, and Swarm missions from 2000 to present. The plot also shows the F10.7 solar flux, a proxy for solar activity, as a shaded region (black line: 81-day mean). The varying altitudes reflect mission lifetimes, orbital manoeuvres, and atmospheric drag effects. *(GFZ Helmholtz Centre for Geosciences, Ingo Michaelis)*

In addition to dedicated magnetic field missions, we are actively involved in magnetic field research through platform magnetometry, which utilizes navigational magnetometers onboard satellites. A key example is the GRACE-FO (Gravity Recovery and Climate Experiment - Follow-On) mission, where we process and calibrate magnetic data from GRACE-FO’s onboard magnetometers, demonstrating how platforms not intended for magnetic field observation can still provide valuable insights into Earth’s magnetic environment when supported by careful data handling and scientific processing.

We have made important contributions to key satellite missions, including CHAMP, Swarm, GOCE, GRACE, and GRACE-FO, through the development of software tools, the creation of scientific data products, and, for CHAMP and Swarm, the support of mission operations. These LEO missions provide a sustained, long-term perspective on dynamic processes occurring within the Earth, its atmosphere, and the surrounding near-Earth space environment. They are essential for investigating the complex, coupled interactions within the magnetosphere-ionosphere-thermosphere (MIT) system. The data collected from these missions supports space weather monitoring, enhances our understanding of the near-Earth environment, and supports technologies such as navigation and communication. Using satellite and ground-based observations, separately and in combination, our research enhances our understanding of Earth’s environment and supports practical applications that benefit society.

Space Weather Monitoring

Space weather refers to the constantly changing conditions in Earth's near-space environment, driven primarily by the Sun’s activity. Solar phenomena such as flares, coronal mass ejections, and high-speed solar wind streams can disturb the Earth's magnetosphere, ionosphere, and thermosphere. These disturbances, collectively termed space weather, can have wide-ranging effects, not only on space-based technologies like satellites and navigation systems but also on ground-based infrastructure.

We contribute to space weather monitoring through our involvement in the European Space Agency's (ESA) Space Weather Service Network. We provide geomagnetic and ionospheric data and services within the SWESNET consortium, which coordinates the pre-operational and development activities of the network's five Expert Service Centres (ESC). Our contributions are focused on two ESCs: the Ionospheric Weather ESC (I-ESC) and the Geomagnetic Conditions ESC (G-ESC). For I-ESC, we provide ionospheric products derived from the Swarm mission. These products include Total Electron Content (TEC), the Rate of Change of TEC (ROT), the Rate of TEC Index (ROTI), electron density, and the Ionospheric Bubble Index (IBI). Monitoring these parameters is essential because variations in the ionosphere can significantly disrupt satellite communications, GPS signals, and high-frequency radio transmissions, especially during periods of increased solar and geomagnetic activity. These data products help improve the accuracy of ionospheric forecasts and support mitigation strategies for space weather impacts. Within G-ESC, we contribute by providing geomagnetic indices such as Kp and Hpo, along with their derivative products. In addition, we supply the Polar Electrojet (PEJ) index, Field-Aligned Currents (FAC), and high-resolution Vector Magnetic Field (MAG) data derived from the Swarm mission. These products support detailed monitoring and modelling of geomagnetic activity and are crucial for understanding magnetospheric dynamics and their impact on ground-based and space-based technologies.

A screenshot of a dynamic 3-day forecast of geomagnetic activity from 13 observatories that contribute to the global Hp30 index. — A screenshot of a dynamic 3-day forecast of geomagnetic activity from 13 observatories that contribute to the global Hp30 index based on median solar wind forecasts of EUHFORIA, ENLIL, and SWPC. The inner circles indicate the predicted Hp30 values using NOAA's colour scale, while the outer rings show the differences between Hp30 and Hs30: blue signifies Hs30 < Hp30, white indicates Hs30 = Hp30, and red represents Hs30 > Hp30. *(GFZ Helmholtz Centre for Geosciences, Ingo Michaelis & Guram Kervalishvili)*

Together with the Geomagnetic Observatory working group, we also provide K-based geomagnetic forecasts that predict geomagnetic activity using data from a global network of geomagnetic observatories. These forecasts combine measurements from individual observatories and apply the same physical principles used to derive established indices, such as Kp (ap) and Hpo (apo). This method allows for accurate and high-resolution predictions of geomagnetic disturbances caused by solar activity, even when real-time solar wind data is unavailable or limited.

Combining Space and Ground-Based Data

Together with the Geomagnetic Field Evolution working group, we support the development of the International Geomagnetic Reference Field (IGRF) by contributing magnetic field data and models. The IGRF consists of spherical harmonic coefficients used to mathematically represent the Earth’s large-scale internal magnetic field and its long-term variation. Maintained by the V-MOD Working Group of the International Association of Geomagnetism and Aeronomy (IAGA), the model is based on data from satellite missions, ground observatories, and magnetic surveys, and is essential for scientific research and practical applications.