Met Office completes upgrade of UK’s rainfall radar network

The Met Office and the UK Environment Agency have completed a £10m (US$14m) upgrade to Britain’s rainfall radar network, enabling the size and shape of raindrops and snowflakes to be captured together with wind speed data for the first time ever. These state-of- the-art upgrades will ultimately lead to improvements in the accuracy of rainfall estimates, particularly during high-impact weather events, such as flooding. The network is one of the longest established radar networks of its kind in the world and consists of 15 radar sites across the UK. Derrick Ryall, head of the Met Office Public Weather Service, said, “Weather radar provides the only means of measuring the spatial extent and distribution of rainfall over a wide geographical area. “The most intense rainfall events are often highly localized and can therefore be missed or under-sampled by rain gauge networks, and while their occurrence can be forecast with skill, it is often not currently possible to forecast their exact location. Radar therefore provides a crucial input to short-range weather forecasts [nowcasts] of precipitation rate, and improves the skill of weather forecasts when it is assimilated into numerical weather prediction models.” The Met Office radar network includes 15 radar stations across the UK, with the oldest, at Hameldon Hill, near Burnley in Lancashire, having been in operation since 1974. The new radar network delivers five times more data, with almost a terabyte being received from each radar over the course of a year. The network can now record 1.8 million rainfall observations per hour per radar and can identify swarms of insects or flocks of birds within a 25-mile radius. Carol Holt, deputy director for the Environment Agency, said, “This joint project with the Met Office is just one of the many exciting ways the Environment Agency is making the most of new technology to prepare for and respond to floods. “The quality and reliability of the data we are getting from the new radars is significantly improved and will help us to provide more accurate flood forecasts and issue flood warnings earlier. This means people have more time to prepare when flooding is expected.” The new radar system was developed in-house by Met Office engineers meaning it has a number of unique capabilities not found on commercial radar. The new technology has not only improved radar coverage, but also the accuracy of rainfall forecasts.