May 18, 2019

Will 5G Undermine Weather Prediction?

There have been a number of media stories this week about a major threat to weather prediction:  the sale of electromagnetic spectrum for new 5G cellphone service.   The problem is that some of the wavelengths being auctioned off for 5G are critical for an important class of weather satellites, with 5G signals potentially undermining our ability to forecast the weather.

Currently, 4G cellphone technologies provide roughly 100 megabits per second (100 million bits per second) of communication speed, while the proposed 5G service could achieve 10 gigabits per second (10 billion bits per second).  Downloading movies and animations would be much quicker, with hardwired connections becoming less critical for most uses. 

But to achieve such service one needs a larger communications highway, which means the use of more of the electromagnetic spectrum.   Electromagnetic energy, such as radio, microwaves, and visible light, are characterized by ranges of wavelength and frequency.  The use of these wavelengths is controlled by our government, which can auction off specific frequency/wavelength bands.

  Among the spectrum recently auctioned off by the FCC for 5G is a band of frequencies near 24 GHz (GHz is gigahertz, or a billion cycles per second).   Unfortunately, this is close to 23.8 GHz, a frequency in which water vapor emits microwave radiation and which is used by weather satellites to determine the three-dimension properties of the atmosphere.  And that information is very important for providing the description of the atmosphere that is required for numerical weather prediction.

Why weather satellite information is important for numerical weather prediction

Numerical weather prediction, the foundation of all weather forecasts, depends on securing a comprehensive, three dimensional description of that atmosphere--known as the initialization.  The better this initialization, the better the forecast. 

One of the key reasons why modern numerical weather prediction has gotten so good is that weather satellites now provide 3D data over the entire planet.  Even over remote oceans and the polar regions.  Roughly 95% of the total volume of weather information now comes from weather satellites.
Before weather satellites, radiosondes were the main source of 
weather information above the surface

And the most important source of weather information is from a collection of satellites that contain microwave sounders.  These satellites observe the earth by sensing microwave radiation being emitted by water vapor, liquid water, ice, and the surface. 

The amount of radiation being emitted can be related to temperature.  And different wavelengths/frequencies reveal the conditions at different levels of the atmosphere.   To put it another way, by sensing emissions at various wavelengths, one can secure a profile of temperatures at various levels in the atmosphere.  Kind of like have radiosondes (balloon-launched weather observations) everywhere.  Very valuable information

The Microwave Sounder Unit on the AMSU-A satellite

What is the most valuable of all satellite observations? 

Satellites with microwave sounders like AMSU-A (see below).  That platform ALONE contributed to a 17% reduction in forecast error in the European Center global model (the world's best)

AMSU A looks at the atmosphere in 15 wavelength/frequency bands or channels,  including sensing the atmosphere at wavelengths that the atmospheric water vapor has peaks in emission (see below). 
Channel 1 is at 23.8 GHz.   The problem is that the FCC has sold off 24 GHz, which is very close to 23.6 GHz.   And if the 5G transmitters aren't very high quality, with little spread to neighboring frequencies, they could well interfere with the microwave weather satellites. 

Why?  Because the weather satellite have very, very sensitive receivers because they are trying to sense the weak microwave emissions of atmospheric water vapor.  These sensors could be overwhelmed by the active TRANSMISSION in nearby wavelengths by thousands of 5G cell tower transmissions or other sources.

And the problem is even worse than that.  The FCC is planning to auction off more wavelengths/frequencies, some of which are close to other wavelength/frequency bands used by the weather satellites.

The potential harm to U.S. and worldwide numerical weather prediction by interfering with the 23.8 GHz band is certainly real, but difficult to quantify exactly. 

First, it will depend on the characteristic of the 5G transmitters and to what degree they will contaminate the nearby weather observation bands.

Second, it depends on how many wavelength bands would be affected.

Third, cell phone coverage does not include the entire planet.  One analysis suggests that only 34% of the earth's surface has cell phone coverage, suggesting that roughly 90% of the planet would be clean of interference (71% of the earth's surface is covered by water).  But if plans to establish satellite-based 5G on commercial ships and aviation come to fruition, the problem would be much worse.

NOAA, NASA, and U.S. Navy are quite concerned about this issue, with the Navy writing a strong statement of the potential harm.  On Thursday, NOAA Administrator Neil Jacobs warned of a potential loss of  1/3rd of current forecast skill.  These warnings need to be taken seriously.

The key now is to have close coordination between the FCC and NOAA/NASA/DOD, as well as other international players, to ensure that spectra close to the weather observing frequencies are not used and, if there are, investments in high-quality transmitters, with effective filters, are required by law.  

Improved forecast skill derived from weather satellites has had huge positive impact on saving lives and property, and in fostering economic growth.  Reasonable actions must be taken to protect the value of weather observations from space.


  1. Using towers for phone communications is a way to maximize profits for the service providing companies, at the risk of harm to humans and animals, spotty coverage, and possible (as Cliff points out) interference with weather forecasts. Cell towers are a stupid way to provide the service, and must in any case rely on fast hardwire connections. The only reason we put up with the unsightly and outmoded cell tower method of communication is because it results in greater profits to CEOs and stockholders, and for profit corporations control what should be a public service provided to all.

  2. Ah well, we’ll go back to ancient rhymes to forecast weather. “Red sky at night, sailors delight”.
    “Red sky in the morning, sailors take warning”.

  3. Mrostron makes good points. A few years ago the FCC proposed a method of sending/receiving Internet data at relative high rates by sending signals over electric power lines. The frequencies proposed were in the high frequency portion of the spectrom and the power lines would make great antennas. The interference would blanket the entire country. Great howls of protest were mounted from many quarters, including several government agencies. A solid gold disaster. The FCCs own data supported the protests but, for two years, the FCC ignored ALL protests. Money talks and politics serves those with money.

  4. I had a friend who worked as a frequency manager at NESDIS. He was allatime going to Geneva for conferences and meetings at WMO. (Our names were exactly the same so I sometimes got his email by mistake.) From him I learned that frequencies are closely guarded and there are laws/treaties involved. So this really surprises me.

  5. Ah, that marriage made in heaven, the FCC and our corrupt representatives in government. Neither new nor surprising.

    In addition to Cliff’s concern about weather forecasting, mrostron comment above mentions possible dangers to human and animal life from 5G cell towers--quite a number of articles on this on the internet.

    It is also interesting to read how the FCC describes itself.

  6. The picture of the radiosonde really takes me back. My dad was a weather forecaster with the Weather Bureau/National Weather Service for many years in Spokane Washington. As a kid I often got to go out and spend a day in the office. Very cool, the chatter of the teletype machines, pilots coming up to the desk for the latest info for their routes. I got to help launch a few radiosondes too.

  7. Thanks for this article Cliff. Good points. All us humans and animals will be impacted too, in ways we do not yet know. Bad deal all around. We are very sensitive to frequencies in our environment, and as a planet, great care needs to be taken to make advancements that benefit all whilst not harming.

  8. An off topic observation: Today, while sunbathing in my backyard, I observed something I never saw before: What I'll call a "reverse contrail". When I looked up I saw what appeared to be an altocirrus cloud cleanly cut in two, and there was a jetliner receding in the background. Cliff, have you seen this? And would you like to explain it? I imagine the heat from the plane's engines vaporized the cloud, but it is odd, because the usual result is condensation in the cold stratosphere, rather than evaporation.

  9. As for cell phone coverage, I am with you Cliff: I call upon the regulators to nix this G-5 proposal. Who cares about it? We are too connected anyway!

  10. Having spent a good portion of my professional career in the RF communications arena, the types of potential interference phenomena described are readily analyzed and specifications may be accurately developed to prevent the type of interference described. In the Puget Sound area consider the very high power FM transmitters on Tiger Mt. These transmitters occupy the 88-108 MHz portion of the spectrum and air traffic control occupies the 118-138 MHz portion. Both the FM transmitters and the ATC transceivers have very tightly controlled spectra to enable simultaneous operation. As long as both 5G users and the weather service users communicate their needs and expectations, I see little cause for alarm. This is not rocket science but rather mundane RF frequency management.

  11. re: Dhudso said: A few years ago the FCC proposed a method of sending/receiving Internet data at relative high rates by sending signals over electric power lines.

    Response: This was a method of doing POINT to POINT internet delivery, and NOT using the lines to connect DIRECTLY _to_ iPhones and tablets and what not. Again, the purpose was to make use of fixed distribution lines for delivery of internet to the home.

    re: The frequencies proposed were in the high frequency portion of the spectrom and the power lines would make great antennas.

    Response: The frequencies used were in the "HF" spectrum, "High Frequency" which means 3 to 30 MHz. Also note these are SW (shortwave) frequencies, such as used by international broadcasters, international aircraft traffic control, and ham radio, as well as armed forces the world over.

    re: The interference would blanket the entire country. Great howls of protest were mounted from many quarters, including several government agencies. A solid gold disaster. The FCCs own data supported the protests but, for two years, the FCC ignored ALL protests. Money talks and politics serves those with money.

    Response: Yes, Internet or Broadband over Power Lines (BPL) was a bad idea, and the FCC was found to be hiding data detrimental to their original contentions.

  12. those big tech companies should upgrade their devices asap before 5G Technology is properly into our lives. this will bring a huge competition between some tech manufacturers like Sony and LG


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