5G will disrupt weather forecasts worldwide

Spektrum der Wissenschaft

4.3.2020

Translation: machine translated

The new 5G mobile communications standard is likely to make weather satellites almost blind to water vapour. Recently agreed protective provisions are not enough, say experts.

5G technology is likely to cause considerable problems in weather forecasting in the coming years. This is because it means that weather satellites will no longer be able to reliably determine the water vapour content of the atmosphere. In order to minimise the problem, meteorological associations have called on the International Telecommunication Union (ITU) to impose strict conditions on 5G operators. However, they now see themselves left alone with their concerns.

The reason for their criticism is the compromise that the regulatory authority reached with the member states at a conference in Sharm el-Sheik, Egypt, on 21 November 2019. According to the ITU, the requirements should initially be comparatively relaxed so as not to hinder the establishment of the new mobile communications standard and increase to a stricter level from 2027 onwards.

However, as the magazine "Nature News" reports on its website https://www.nature.com/articles/d41586-019-03609-x, the compromise does not go far enough for meteorologists. If 5G networks develop faster than estimated by the ITU, there is a risk of a loss of quality in weather forecasts worldwide. The experts refer to studies by NASA and the US atmospheric research agency NOAA, among others.

In concrete terms, the debate revolves around the question of how much disruptive noise network operators are allowed to produce on a frequency that is important for weather forecasting. At 23.8 gigahertz, water vapour in the atmosphere emits a weak signal that weather satellites receive to determine humidity even in the dark. If a 5G network now transmits at 24 gigahertz, there is more or less strong noise on the neighbouring frequencies. As a result, the satellite reports more water vapour than is actually present.

These interference signals are measured in decibel watts (dBW). According to the US Space Agency, the noise should be limited to -52.4 dBW, a requirement that the World Meteorological Organisation (WMO) had agreed to in terms of magnitude. The European regulatory authorities had brought a higher value of -42 dBW into play, while their US counterpart even proposed -20 dBW. The compromise now provides for -33 dBW until September 2027 and -39 dBW thereafter.

It remains to be seen whether this will be enough to protect the weather satellites' data collection. In a statement, the European Centre for Medium-Range Weather Forecasts in Reading, southern England, condemned the measure as inadequate. Once again, science has not been listened to on an important issue, writes the centre. Economic interests continue to be weighted more heavily, even in times when society has to pay the price for science's warnings about the impending climate crisis being thrown to the wind.

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