How satellite data are used in Romania

Spotting mountain wave breaking for flight safety

When water flows over rocks on a riverbed, it can create waves that disturb the river’s flow. In a similar way, winds that cross over mountains can create gravity waves in the atmosphere. In certain atmospheric conditions, the oscillations created, known as mountain waves, can occasionally break, leading to severe or even extreme turbulence, which can be damaging to aircraft of all sizes.

“It’s extremely important for aviation safety to identify the areas of severe turbulence created by mountain waves, particularly breaking waves which can manifest up to 20 kilometres above the ground,” said Dr Paul Bugeac of the Romanian Air Traffic Services Administration (ROMATSA). ROMATSA provides air navigation services, including aeronautical meteorological information to users such as pilots, air traffic controllers, flight operators, and search and rescue services.

Sometimes the presence of turbulence caused by mountain waves can be deduced from tell-tale cloud patterns. But mountain waves can also create clear-air turbulence that can be hard to spot. To map them effectively, air traffic services must therefore bring together a wide range of satellite observations that can shine light on parameters such as cloud cover, atmospheric stability, and humidity.

Developing and utilising products that allow them to quickly make sense of these data, means that the experts at ROMATSA are able to warn users of potential dangers. “Based on a conceptual approach we developed on mountain wave breaking, we can use satellite data to identify specific areas of severe and even extreme turbulence,” Bugeac said.

Bugeac’s colleague Mr. Alexandru Hozoc explained that satellite data provided by EUMETSAT Meteosat satellites also provide essential information that enables the prediction and monitoring of other hazardous weather phenomena, including thunderstorms, icy conditions, and turbulence.

ROMATSA uses these data to make forecasts and warnings that contribute to the safety of flights, Hozoc explained. It also enables them to provide risk assessment and reduction strategies for flight operators. “The ultimate goal is for all aviation service providers to not only be able to predict events, such as the evolution of adverse weather areas, but to be prepared to mitigate risk scenarios whenever hazards manifest themselves,” he said.

Tracking Saharan dust

Saharan dust clouds high in the sky can create spectacular sunsets. Yet unlike sand you might find on a beach, the fine-grain particles lofted into the atmosphere by winds blowing across the world’s largest hot desert can contain many hazardous particles and allergens. These can cause respiratory problems such as pulmonary diseases and asthma in people, as well as other issues. 

Dr Bogdan Antonescu, an atmospheric scientist at the National Institute of Research and Development for Optoelectronics (INOE) explained how the organisation is using satellite data to support research into the effects of dust clouds. He explained how in March 2018, parts of Romania woke up to an unusual sight: the ground was covered in orange snow – the effects of a record-breaking Saharan dust cloud.

Saharan dust clouds over Romania are relatively rare in winter time, and the event provided researchers an opportunity to learn more about the chemical nature of dust in the snow and identify potentially hazardous particles. “We could use our instruments on the ground to understand, using laboratory studies, what the composition of the orange snow was,” he said. “But we needed satellite data to understand what was happening on the larger scale.” 

In order to learn how the dust cloud shifted and shaped over time, experts turned to satellite data and data reanalysis. Their studies included analysis of RGB images of the dust plumes obtained from Meteosat Second Generation’s Spinning Enhanced Visible and InfraRed Imager (SEVIRI). The researchers also made use of the Copernicus Atmosphere Monitoring Service (CAMS) global near-real time analysis and forecast system. “The satellite data allowed us to learn how the Saharan dust reached Romania,” Antonescu explained.

While much is known about the levels of particle pollution found in the air in urban areas and beyond, far less is known about what it is made up of. To better understand questions in relation to this, and many others, Antonescu pointed out that INOE also takes part in international projects such as the Satellite Based Monitoring Initiative for Regional Air Quality (SAMIRA). Antonescu said such international collaborations have enabled the development of maps of ground-based particle matter and other types of gases. These maps can help authorities to monitor air quality and issue warnings about conditions that could be potentially hazardous to health.

Improving flood predictions

River floods are one of the most destructive natural disasters worldwide and climate change is widely expected to make them more frequent and extreme in the coming decades. Yet floods can be very difficult to predict.

Dr Marius Matreata, Director of Romania’s National Hydrological Forecasts Centre (NHFC), part of the National Institute of Hydrology and Water Management, explained how the Centre is using satellite data to support the delivery of short-, medium-, and long-term flood forecasting and warnings across Romania.

Romania’s landscapes, culture, and economy are intertwined with rivers – the country is located almost entirely within the Danube river basin. But heavy rainfall can result in major flood events. NHFC uses a national forecasting and modelling system that also integrates satellite and ground-based data to simulate and forecast hydrological processes in Romania in real time. Specialised hydrological modelling components support real-time simulation and forecasting of hydrological processes at different spatial and temporal scales, Matreata explained.

NHFC is also partner in regional cooperation projects, like the European Flood Awareness System, which make use of EUMETSAT Satellite Application Facilities, and the South East Europe Flash Flood Guidance System, which is using National Oceanic and Atmospheric Administration HydroEstimator satellite-based precipitation estimates.

Next-generation satellites such as EUMETSAT’s forthcoming Meteosat Third Generation (MTG-I) series will provide tremendous opportunities to further improve flood predictions, Matreata said. For instance, data collected by MTG-I satellites will significantly boost both numerical weather predictions and nowcasting capabilities across Europe.

Matreata added that the development of hydrological forecast products to take advantage of the increasing volumes of data is both a huge challenge and opportunity. “These could be crucial, especially for flooding events,” he said. “The new generations of satellite sensors and products could help us to detect initiation of intense surface runoff formation. Over the next five to ten years we will use more and more satellite products, both for real time operations and for the calibration and validation of hydrological forecasting models. We will be able to significantly improve our hydrological forecasting and modelling products and their spatial and temporal resolution.”