The Shannon Airport Rainfall Radar Met Éireann

Power failures and overheating cause long-term outages at Ireland's 'most important' weather radar

The Shannon Airport Rainfall Radar has been taken offline a number of times this year.

POWER FAILURES, OVERHEATING and positioning problems were among the reasons behind long-term outages at the country’s “most important” weather radar this year.

Records released to following a Freedom of Information request detail the various problems that affected the Shannon Airport Rainfall Radar throughout 2019.

The radar provides coverage of rainfall and wind in south-western counties, and is used by Met Éireann as part of its weather forecasts for that part of the country.

The radar was first installed in 1996, and is described by the forecaster as “arguably the most important radar in Ireland” because it is the first to detect weather from the south-west.

However, it was hit by a number of outages during the course of the year, resulting in significant losses of rainfall coverage in the west and south-west, sometimes for weeks on end.

Internal email correspondence reveals why those outages occurred, and how staff at Met Éireann attempted to remedy the issues the led to them.

The first major outage occurred on 3 August, when the radar was forced to go offline for almost two weeks.

The outage was caused after a “technical issue”, which required replacement parts to be ordered from Germany and fitted to the radar.

But documents show that this outage followed a number of issues in July, when staff at Met Éireann reported problems with the calibration of an antenna on the radar.

‘Nodding around’

Subsequent emails between Met Éireann staff in late August also refer to calibration testing following the installation of a part from a German supplier that month, indicating that the issue led to the radar being taken offline at the start of August.

On 3 July, one staff member sent a general email noting that the radar would be taken offline for a number of hours because it was experiencing “elevation control” (ie positioning) problems.

In a follow-up email, they explained that the dish’s antenna was more than one degree off its calibration, and was attempting to remedy this with a corrective signal.

The staff member explained that this resulted in readings from the dish “severely nodding around” their nominal value.

They also said that the inability to distinguish bad data from accurate data meant it was unknown how long the problem had been ongoing, despite being identified on 25 June.

But they suggested that the issue had been remedied after a part had been replaced, and no more issues were reported with the radar’s calibration afterwards. 

Power failure

On 17 October, the radar was taken offline again after it experienced a second technical fault, which occurred after a critical power supply at its receiver failed.

According to internal documents, staff at the forecaster initially remedied the problem by replacing the power supply the following day.

However, they were forced to stop the radar from transmitting after experiencing “severe noise” while doing so.

Another new power supply was fitted on 21 October, before the radar suffered another major outage following another issue on 24 October.

On 25 October, a Met Éireann staff member issued an alert to explain the latest problem:

The Shannon Radar gave control problems last night, that led to more serious problems today. Work on its repair began this morning but have not come to any conclusion. Therefore the radar will be down until Tuesday 29 October at the earliest.

On 29 October, an update explained that the radar’s antenna was moving “erratically” when the radar’s elevation was moved too much.

Although the radar was functioning at the time, it was left operational to allow data to be recorded and users were told to “treat it with caution”.

The following day, staff were told that the radar was still operating erratically.

“There is an instability in the elevation movement and sometimes in the azimuth, an email read. 

“This instability is preventing a calibration being done on the antenna.  A replacement control board was inserted today into the elevation control but without success. A second board can be inserted tomorrow and the process repeated.”

But on 31 October, staff were told that the repair of the radar had become more serious because of a risk of overheating.

“The makers of the radar have been requested to engage with the problem directly and to provide an engineer to visit and service the radar,” staff were told.

“Therefore the radar will remain off air until this has been resolved.”

The issue persisted until 25 November, a month after the first outage occurred, when works carried out by the manufacturer were completed.

In a statement during the outages, Met Éireann apologised to those in affected counties for the loss of coverage.

It also said that it is planning a major programme to expand and modernise Ireland’s weather radar network, which it expects to meet the country’s needs to 2040.

However, it is not yet known when these upgrades will take place.

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