Just a few weeks after its successful launch into orbit in mid-August, the first satellite from the revolutionary MetOp Second Generation (MetOp-SG) series, known as MetOp-SG-A1, has already begun to send its first data. These early signals from space provide an exciting glimpse into a new era of meteorological observations and confirm that Europe is on the verge of a technological leap in weather and climate monitoring.

The MetOp Second Generation mission is the direct successor to the highly successful first generation of MetOp satellites, which have been the backbone of global numerical weather prediction for decades. The new program not only ensures the continuity of crucial data necessary for daily weather forecasts and long-term climate change monitoring but also brings vast improvements in the precision, resolution, and volume of the information collected.

A new era in European and global meteorology

In a time when extreme and unpredictable weather events are becoming more frequent and intense, accurate and timely forecasting has never been more important. From devastating hurricanes and floods to prolonged droughts and heatwaves, the consequences of climate change are being felt across the planet. It is in this context that the MetOp-SG satellites, operating from a polar orbit at an altitude of about 830 kilometers, will provide the fundamental data needed to enhance weather prediction models and deepen our understanding of the complex processes that govern Earth's climate system.

The entire mission consists of three successive pairs of satellites, ensuring operational capability and data flow for at least the next two decades. Each pair consists of an 'A' type satellite and a 'B' type satellite, which carry complementary instruments to record the widest possible spectrum of atmospheric and surface observations. This dual approach allows for a comprehensive scan of the Earth, covering parameters from temperature and humidity in the atmosphere, to winds over the ocean, to air composition and the state of the ice.

This ambitious project is the result of a long-standing and successful collaboration between the European Space Agency (ESA) and the European Organisation for the Exploitation of Meteorological Satellites (Eumetsat). ESA is responsible for the design, development, and construction of the satellites themselves, while Eumetsat manages the launch services, development of the ground segment, in-orbit satellite operations, and the distribution of invaluable data to the meteorological community worldwide.

Launch and first steps in space

The MetOp-SG-A1 satellite was launched on August 13, 2025, on an Ariane 6 rocket from Europe's Spaceport in French Guiana. Since that moment, Eumetsat's teams have been conducting a rigorous commissioning phase. During this multi-month period, all systems and instruments on the satellite are thoroughly tested, calibrated, and verified to ensure their full functionality and data accuracy.

Although the satellite has been in orbit for just over twenty days and the commissioning phase is in its very early stages, two of its key instruments, the Microwave Sounder (MWS) and the Radio Occultation sounder (RO), have already begun to return their first, preliminary data. This success represents a significant milestone and confirms that the mission is proceeding according to plan, marking the beginning of a new era of European weather and climate monitoring.

Revolutionary instruments send their first signals

The technological advancements built into the instruments on the MetOp-SG-A1 satellite will allow scientists and forecasters to obtain information with an unprecedented level of detail. The first data from the MWS and RO sensors already show enormous potential.

Microwave Sounder (MWS): A more precise view into the atmosphere

The Microwave Sounder (MWS) is a key instrument for obtaining vertical profiles of temperature and humidity through the atmosphere. It combines the functionalities of three instruments from the first generation of MetOp satellites (AMSU-A1, AMSU-A2, and MHS) into a single, unique instrument with one antenna. In addition, the MWS has new channels specifically designed for detecting ice clouds and measuring temperature and humidity with improved precision. One of the most important improvements is the horizontal resolution of the temperature sounding channels, which has been improved from approximately 48 kilometers on the previous generation to just 20 kilometers at nadir (the point directly below the satellite).

The instrument began taking measurements just a week after launch, and a striking image, representing a 24-hour recording from August 24 from its Channel 17, clearly shows this. In addition to the properties of the Earth's surface, this channel is also sensitive to convective clouds, which are shown as distinct filaments and band-like structures over the oceans. For example, the red swirl visible in the North Atlantic reflects the deep convective cloud system of former Hurricane Erin. In practice, the information from the 24 different channels of the MWS will not be used in isolation; it will be combined to obtain detailed products on atmospheric temperature and humidity at different altitudes above the Earth.

A second published image, from MWS Channel 2, clearly shows a band of summer 'brightness temperatures' (expressed in Kelvin) over land and ocean across Europe. This data will allow forecasters to more accurately track temperature anomalies and heat waves.

Radio Occultation sounder (RO): Three times more data for better models

The second instrument that has already sent data is the Radio Occultation (RO) sounder. It provides extremely detailed profiles of atmospheric temperature and humidity through the troposphere and ionosphere. This instrument is based on the heritage of the GRAS instrument from the first generation of MetOp satellites but brings a revolutionary improvement: it triples the number of radio occultation measurements, providing more than 1600 observations per day. This leap in coverage is made possible by the inclusion of signals not only from the American GPS but also from the European Galileo navigation system and China's BeiDou. As the first coverage image shows, the new measurements include a larger portion of the global oceans, where data has traditionally been relatively sparse and insufficient.

The smaller graphs show vertical profiles of temperature and humidity obtained from the instrument's first measurements on August 20 over the South Pacific. The curves are shown alongside forecast data from the European Centre for Medium-Range Weather Forecasts (ECMWF), revealing how RO measurements refine and update predictions of temperature and humidity structure, especially in data-sparse areas. Both instruments, MWS and RO, will provide input data of unprecedented precision for numerical weather prediction, which will ultimately lead to more reliable and accurate weather forecasts.

The path to operational data and strategic importance

Although these early signals are extremely encouraging and show that progress is proceeding at a great pace, it is important to emphasize that the data is not yet operationally qualified. The commissioning phase of the Metop-SG-A1 satellite will require months of thorough testing and calibration before any data is released to the meteorological services of member states and other users.

Phil Evans, Director-General of Eumetsat, stated: "Receiving this first data so quickly is an exciting achievement for Eumetsat, especially given the technological sophistication of Metop-SG-A1 and its payload. In collaboration with ESA and our European industrial partners, Eumetsat's teams are working intensively to make all of the satellite's instruments operational, and the fact that data is already flowing seamlessly from the MWS and RO shows that we are firmly on the right track to having powerful, validated products ready for our user community on schedule."

Simonetta Cheli, Director of ESA's Earth Observation Programmes, added: "These first data insights are extremely encouraging, and I want to thank all the teams that have contributed – both to the development of the mission as a whole and to the work and commissioning of MetOp-SG-A1 in orbit. This is a major undertaking: a total of six satellites, flying in successive pairs and delivering crucial data for at least the next 20 years. While we are closely monitoring the early performance of MetOp-SG-A1, we are already in the final stages of preparing its companion, MetOp-SG-B1, for launch next year."

Together, the polar-orbiting MetOp-SG mission and the geostationary Meteosat Third Generation (MTG) mission firmly position Europe at the forefront of global weather prediction. While the MTG satellites from geostationary orbit provide a continuous view of Europe and Africa, enabling the monitoring of rapid weather phenomena such as storms, the MetOp-SG satellites from polar orbit provide global coverage and detailed atmospheric profiles crucial for the accuracy of numerical models on a scale of several days to weeks. This synergy of two leading satellite missions will provide Europe and the world with the most advanced tools to face the challenges brought by climate change and increasingly extreme weather conditions.