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Developing weather radars for tomorrow's world

15 radar sites. A 30-year-old network. One ambitious plan. In 2017 the Met Office’s project to renew all the weather radars comes to a close – but the benefits it will bring are only just beginning.

Spanning the UK, the Met Office radar network provides real-time precipitation data to forecasters, scientists and a range of organisations. Together with our partners we use that data in two key ways: for monitoring the current weather situation, and forecasting via computer modelling. It’s a job the radars have been doing for decades, feeding everything from television reports to weather alerts and helping partners monitor flood risk. But with the advent of new technologies, fresh infrastructure needs and inevitable weathering, it was time for an upgrade. Following an extensive planning phase, 2010 saw the start of a seven-year roll-out.

Driving change

Many of the radar sites date back more than 20 years, so there was a practical reason behind much of the work. “Some of the locations, such as the one up on Stornoway in the Outer Hebrides, mean the radar can get quite weathered,” says Richard Bennett, Senior Project Manager at the Met Office. So one of Richard’s tasks was to source and manage local suppliers who could lend their expertise to this epic task.

While the main driver for change was to replace an obsolete and increasingly difficult to maintain system, there are a number of spin off benefits associated with the newer technology. “We can now use radar in a larger variety of ways than we originally envisaged, and harness new technologies,” Richard explains.

First came Doppler, allowing the radars to observe how the rainfall is moving, and therefore measure the wind as well as the rainfall. Next was dual polarisation. Enabling the radar beams to travel both horizontally and vertically through the atmosphere means that the Met Office can now examine the shape of raindrops. In turn, understanding more about their structure will help forecasters accurately pinpoint the difference between rain, hail and snow. And that means they can provide clearer and more accurate information about heavy rainfall – especially during high-impact weather.

Clearing the way

The twofold introduction of Doppler and dual polarisation is a huge leap forward. Not only will the enhanced network enable the Met Office – and our customers – to benefit in current weather events, it will also help with improving the quality of short period forecasting with an unprecedented quantity of information being returned by the radar. “Because we scan so close to the horizon, we had occasional problems with the beam deflecting off ‘ground clutter’, such as hills giving us what we call spurious returns,” explains Richard.

But now, the radar visuals can be cleaned up for a more realistic picture of what’s happening. Ultimately, this clearer, more accurate realtime information will have an impact on short period forecasting such as weather and flood warnings, benefitting everyone who relies on the rainfall information the network produces, including the general public.

Efficient, effective and at the cutting-edge

At a practical level, the radars will also operate more resourcefully than before, leading to less call-outs and downtime. And the Met Office sees those efficiencies extending long into the future. “We’ve developed and deployed a system ourselves rather than using something off-the-shelf,” says Richard. “That gives us the flexibility to develop it even more as the network grows.” Future-proofing has been front of mind throughout the project. These state-of-the-art systems should equip the radar network for at least the next 10-15 years.

Now that the project is coming to a close – with the last few upgraded radar sites due to be up and running again shortly – Richard is reflecting on a job well done: “Looking back, it’s been a real team effort. As we’ve switched one enhanced radar back on, we’ve been testing another and starting the upgrade on the next one. But we’ve had the support of a range of local suppliers, and the Environment Agency which co-funded the project. It’s good to celebrate what we’ve achieved together – and personally, to witness progress happening has been a great feeling.”

Watch a time-lapse video of the High Moorsley radar installation on the Met Office YouTube channel.

Planning ahead by working together

The radars and the information they can now deliver are of vital importance to the Environment Agency which co-funded this project.

“For the Environment Agency, a clear, timely picture of weather behaviour is crucial for mapping rainfall rates and locations, then forecasting potential flood impacts on communities downstream so that people and responders can take action to save lives and livelihoods,” said Liz Anspoks from the Environment Agency.

Enhanced real-time data, thanks to dual polarisation in particular, will bring huge benefits to the Met Office too – supporting decision-making and potentially improving the speed at which we can get alerts out in extreme weather.