Aircraft wing

Real-time observations are taking off

26 March 2014

Aircraft provide an essential way to gather weather data. For several years, an international programme has ensured that meteorological offices across Europe are pooling data from flights to build an even more detailed picture of weather conditions.

To map, understand and predict the weather, it's vital that every national weather service has as much up-to-date observational data as possible. That's the thinking behind EUMETNET, a programme of 30 organisations across Europe that have joined together to pool resources and observations. By collaborating, each country benefits from having more data at its disposal, and avoids any wasted cost in duplicating work being done elsewhere.

EUMETNET members share observations from a several different sources, such as radiosondes from ships and water vapour measurements using satellites. Some of the data sharing projects are compulsory for members of the collaboration, including E-AMDAR (EUMETNET Aircraft Meteorological Data Relay), which covers the gathering of observations from commercial airline flights. E-AMDAR is part of a wider AMDAR worldwide community under the World Meteorological Organization (WMO).

It's standard practice for all commercial airlines to take a number of observations as they fly, including static air temperature, air speed and ground speed (from which it is possible to derive wind speed) and indication of turbulence. E-AMDAR enables meteorological offices to harness this data, process it and transmit it onto the World Meteorological Organization's Global Telecommunications System. The data is vital especially as, apart from radiosondes, AMDAR is currently the only source of atmospheric,

in-situ observation. Obviously, when more airlines are signed up to the programme, more data can be collected and harnessed for Numerical Weather Prediction (NWP).

More and better data

The E-AMDAR team is headed up by Steve Stringer. Steve started managing the programme in early 2013, after having worked in radiosondes and, as he puts it, "all things upper air". The programme is a rich source of observational data that is vital for NWP. Steve explains, "As the processing power of the models increases, they grow hungrier and hungrier for data." E-AMDAR helps to provide that real-time information.

All the data that the aircraft provide is processed and made available for the models and other countries in EUMETNET to use incredibly quickly. Predictive models are run every three hours, with some now running every hour and ideally needing fresh data within 15 minutes of the observation being made. Currently about fifty per cent of data from aircraft is available within this time window.

Steve would like to make sure that even more data is available as quickly as possible. One challenge is that aircraft take observations every seven to eight minutes, but send them in batches. In effect this means that the first piece of data in the batch can be over 60 minutes old.

Another important objective for Steve is to increase the breadth of data coming in. Flights tend to be seasonal, with a greater number heading to sunnier climates in the summer months, for example. There can also be geographical gaps - as the weather of Europe is largely determined by events to the west, it

is crucial that airlines operating across the Atlantic are contributing. As such, Steve is targeting airlines in Iceland and the Azores to build up the observations profile. Since taking up his role, Steve has already signed up one new airline and is in conversation with a number of other operators.

Airlines can see the benefits straight away. They rely on meteorological information and predictions to operate safely, so are happy to play a part in contributing to richer, more in-depth data. Steve works with European meteorological partners on a day-to-day basis, sharing knowledge and expertise across WebEx and other portals. It's through this kind of collaboration that the world will gradually build an ever more accurate picture of global weather systems. "We couldn't survive or provide the services we do without global observations like these," explains Steve.

A vision for the future

All commercial aircraft have to take temperature and wind readings, but EUMETNET partners would value humidity readings too. However, to adapt an aircraft to take humidity readings is costly and time-consuming. It involves putting an inlet on the exterior of the aircraft, and sensors on the interior. In effect this means cutting a hole in the skin of an aircraft, which takes a lot of certification and design work before approval.

The best-case scenario would be where national federal aviation authorities bring in a ruling that all new aircraft have to be equipped to take humidity readings. Steve's vision is extremely focused: "We want to see all aircraft roll off the assembly line with the hardware and software already fitted to provide basic meteorological observations when and wherever the aircraft fly - irrespective of the airline."

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