The wind watchman
Dr Federico Cossu combines data from sources such as EUMETSAT’s Advanced Scatterometer (ASCAT) to make better wind observations for weather forecasts
Meet EUMETSAT’s Research Fellows: Dr Federico Cossu explains how he is bringing together data from different sources to provide better observations of winds, one of the biggest challenges for improving forecasting
To do this, Cossu makes use of data provided by satellite instruments such as EUMETSAT’s Advanced Scatterometer (ASCAT) on Metop polar-orbiting satellites. ASCAT transmits pulses of microwave energy, as a radar, towards the sea surface, recording the resulting echos.
The instrument collects these echoes, which are ‘backscattered’ from small waves on the ocean surface – with a wavelength of a few centimetres – and translates it into a wind measurement through advanced software developed by EUMETSAT.
Despite being at an altitude of 817 km, ASCAT can accurately measure the unique characteristics of the backscattered radar signal caused by the wind-roughened ocean surface. As the sea surface roughness correlates closely with near-surface wind speed and direction, ASCAT can provide a clear picture about wind conditions over a broad area.
“Each method we use has distinct advantages and disadvantages for observing wind,” Cossu says. “Buoys, for instance, have the advantage of taking direct wind measurements in situ, where the winds are happening. But in the open ocean they are often in short supply. On the other hand, scatterometers can provide wind information across the global ocean.
Cossu's project is also benefiting from newly available wind products, such as those derived from the recently launched Atmospheric Dynamics Mission-Aeolus (ADM-Aeolus). ADM-Aeolus uses a space-based doppler wind lidar, beaming an ultraviolet laser through the atmosphere, which scatters off air molecules, water droplets, and dust particles, enabling meteorologists to take 'direct' wind measurements from satellites.
“I feel privileged because I am one of the first users to have access to such a broad range of data,” Cossu says. “The work that goes into the delivery of these data is the collective effort of hundreds of people over many years.
“Being an EUMETSAT fellow has the advantage of having direct access to an amazing network of researchers to collaborate with, learn from, and explore ideas with. I have been provided with excellent tools, supervision, and funding. When I see how our research is appreciated by the community, it is a huge motivation.”
EUMETSAT Research Fellowships
In close partnership with its Member States, EUMETSAT funds a limited number of research fellowships to support young scientists in developing new uses and applications of satellite data. Through this series of articles, we showcase some of the fascinating projects Research Fellows work on, which include assimilation and analysis of satellite data to support weather prediction models; the use of satellite data for climate applications; and the development of new products and applications in areas spanning oceanography, hydrology, and atmospheric composition. EUMETSAT Research Fellows are hosted by institutions within EUMETSAT Member States, who also coordinate applications to the programme in response to an annual call for proposals.
Main image courtesy of Federico Cossu.