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Weather Monitoring Frequencies Subject to Pollution
jd writes "In a case of technology vs. technology, the ICU (the body governing the use of radio frequencies around the globe) has been asked to secure radio frequences used for weather monitoring. In-car radar, mobile phones and other commercial and military applications are now using these same frequencies. However, weather satellites can't simply be re-tuned. There is only one very narrow band that detects water vapor but not liquid water, for example. This frequency has been sold to developers of car radar systems. The more this happens, the less useful weather radar and weather satellites will be. The noise will simply swamp the data, making what is collected useless. The article doesn't give a 'doomsday' timeframe, when we'll have no better ability to forecast the weather than they did in the 1800s, but that is what they are talking about."
Why would your car radar be useful if the signal it emits is attenuated by water vapour? Drive through some fog & you're in trouble.. ?
No Norm, those are your safety glasses; I'll wear my own thanks...
Remember that a meteorologist is a TV starlet. He/she needs to show up, in addition to a pretty face/boobs/legs or for whatever reason them "huaping" now are hired, some spectacular results. Thus, they run several simulations on them Beowulf clusters and then pick something that may be presentable on the screen.
Weather prediction relies heavily on Navier-Stokes' equations, which are more sensitive than my girl friend's pussy; change a parameter one percent and that smooth sailing wind may turn into a storm. Meteorologists don't understand how to deal with these equations, but they know that they are a tricky son of a bitch.
Basically, the only way to make the predictions better is to further minimize the FEM elements used in the calculations, which means even bigger Beowulf clusters (or equivalent). It also means that we need to have the best and most accurate data available to these simulations. I can easily see the predictions go way down south if the water parameters are fucked up the slightest. So we need to reserve them frequencies, or come up with a technique to filter out disturbances (vertical/horizontal direction comes to mind when talking about satellites).
Weather predictions are generally speaking utterly unimportant, but sometimes they help save lives by warning for tornado build ups and similar. It is merely a matter of weighing the costs against the gains, as always.
Ever been to LA...
You can drive in any direction for between 5 and 20 hours depending on day and traffic conditions, and never leave the monotonous suburban landscape. It's the results of unplanned, unconsidered, growth. From space it looks like the great god of suburban blight dropped it "Splat" from high altitude like some surreal cow patty.
What the hell (you might ask) has any of that got to do with this article. The answer is that the same kind of thinking (or kack there of), is behind the morass that is our use of the electromagnetic spectrum.
Empire building, despotism, political back-biting, greed and intrigue, technology working around the ideocy that is our regulatory system, and nobody asking whether the left hand knows what the right hand is doing... A Chinese Fire Drill would look like close order drill compared the slow motion Loony Tune that passes for what we've got.
Sanity might look like;
1. Determine that spectrum which serves to valuable or significant a purpose to avoid protecting, and declare that sacrosanct. Being able to track water vapor by the way is one of those sacrosanct uses.
2. Give up on that selling the spectrum for fun and profit idea... it was a bad joke then and it hasn't gotten better with time.
3. Put the millitary on a sane leash (they really don't need 50% of the workable spectrum.)
4. Promote the hell out of advanced mutispectrum technologies and count the money.
We really need to get a few folks in the FCC who haven't technological myopia, and have the cojones to push through an agenda based on growing use, and growing technology.
Genda Bendte
It's the same with BPL. Now it's more important to use the frequency spectrum for businesses, despite its critical importance for public services. We will see the consequences in some years; just wait for the coordination in case of a catastrophe failing due to HF pollution, or to miss the prediction of an important storm due to polluted data.
It seems that nowadays there is a sort of inherent "right" to turn anything into business, completely ignoring the impact to the public.
Ok, water vapor sensing is exactly what I did for my master's thesis. I'm going to keep it brief though.
Water vapor has an absorption line centered at 22.235 GHz while liquid water's absorption increases with frequency^1.95. Vapor sensing radiometers do not generally measure at 22.235 GHz because the peak of the absorption line curve is extremely sensitive to pressure. There are points to either side where the curve is insensitive to changes in pressure allowing measurement throughout the entire atmosphere without having to know the pressure profile. That is why the scientists in the article want to keep the 23.6 to 24.0 GHz band for their measurments.
My radiometer measured the emission spectrum at 21.6, 22.235, and 31.6 GHz. 21.6 and 31.6 GHz were the measurements of vapor and liquid water, respectively. 31.6 GHz is a window between the 22.235 GHz vapor line and the group of oxygen lines around 60 GHz. This makes liquid the strongest contributor to the noise temperature at that frequency. The 22.235 GHz was to experiment with. By using 22.235 and 21.6 I tried to see if I could get reasonably similar results even though both frequencies were more sensitive to vapor than liquid. Two close frequencies are measureable using one antenna thereby making the radiometer less expensive and available for more widespread use. I showed that the measurement could be made, but a lot more data needed to be taken to refine the data processing. Enough information was there in the measurements, but there were factors I couldn't account for in the time I had. Hopefully in time, radiometers could become a much more common piece of weather sensing equipment. You can get a lot more data on vapor with a radiometer than you can with a weather balloon, but radiometers are currently expensive and therefore limited in usability. Water vapor is the single biggest driving factor in the weather, we NEED to be able to measure it. Cheaper radiometers would let us get more data and improve weather modeling.