With hurricanes battering the US, Europe just coming out of another hot summer, and all signs pointing to climate change – weather dominates both our headlines and our policy-making. But did you know that European GNSS plays an important and growing role in meteorology?

When it comes to meteorology, Galileo – and GNSS in general – can play both a direct and indirect role, especially as regards mitigating the effects of climate change. As the EU works to establish a resilient energy policy with a forward-looking climate change strategy, it is increasingly looking to space for answers. From providing the maps for finding the best locations for renewable energy infrastructure to outlining the most fuel-efficient flight paths, enabling precision farming, optimising road transportation routes and monitoring CO2 emissions, Galileo, EGNOS and Copernicus (Europe’s Earth observation system) provide innovative solutions to many of today’s weather-related challenges.

Whereas Galileo determines a precise position anytime, anywhere on the globe, Copernicus provides information on the Earth’s surface, its atmosphere and marine systems. By putting the two together, one can unleash synergies that results in multiple benefits for users.

“One area where we are already seeing the benefits of combining these programmes is with creating sustainable solutions to climate change,” says GSA Executive Director Carlo des Dorides. “For example, both Galileo and Copernicus use satellite signals and data to help develop a better understanding of climate change and environmental issues via the accurate observation and measurement of, for instance, the state of the oceans or the chemical composition of the atmosphere.”

Also read: Galileo-Copernicus synergies explored at Prague Copernicus forum

In a more specific context, Galileo provides better weather forecasting by helping to estimate the water vapour in the atmosphere. Water vapour is routinely used for numerical weather prediction, along with very short weather prediction (i.e., now-casting). It is also helpful for monitoring the greenhouse effect and climate change. To accomplish this, GNSS meteorology uses a combination of GNSS signals and GNSS permanent reference stations. The lower part of the atmosphere (i.e., troposphere) introduces delays on GNSS signals, which are estimated during the positioning process. The raw data gained from GNSS permanent reference stations is then processed and analysed in order to estimate tropospheric products. With the knowledge of surface pressure and temperature, together with various mapping functions, one can more easily evaluate Zenith Total Delay (ZTD) and Integrated Water Vapour quantity.

Of growing importance

In the future, GNSS and Earth Observation will likely see a growing role in forecasting and fighting climate change. “If you look across the entire chain of weather service development over the course of the past five years, you will see satellite-based technologies becoming increasingly important for global observations, atmospheric modelling, and forecasting/delivering weather information to end users,” says des Dorides.

In general, multi-GNSS brings great opportunities for the real-time determination of tropospheric zenith total delays and integrated water vapour, thus improving numerical weather prediction, particularly for now-casting and severe weather monitoring. As a result, multi-GNSS processing will improve the accuracy of tropospheric products due to an increased number of observations and improved coverage of azimuth and elevation angles.

“GNSS is particularly well-positioned to provide more localised and instantaneous weather services, as weather observing networks that use GNSS are able to produce much more accurate weather data than what is available using conventional fixed network methods,” adds des Dorides.

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