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Spire Plans To Use Tiny Satellites For More Accurate Weather Forecasts
Zothecula writes Weather forecasting is a notoriously inexact science. According to San Francisco-based tech startup Spire, this is partially because there are currently less than 20 satellites responsible for gathering all of the world's weather data – what's more, some of the older ones are using outdated technology. Spire's solution? Establish a linked network of over 100 shoebox-sized CubeSats, that will use GPS technology to gather 100 times the amount of weather data than is currently possible. The first 20 of those satellites are scheduled to launch later this year.
The last I looked, the state of remote-sensing algorithms for limb profiling (i.e., looking through the layer of the Earth's atmosphere over the limb of the planet from your orbital position) is something between bad and "are you kidding?".
I wonder what kind of secret sauce these Young Turks have that NASA and NOAA doesn't?
Welcome to the Panopticon. Used to be a prison, now it's your home.
is missing in this notion. Meaningful Earth observation from space is done with cameras that take up more physical space than a cubesat. Yeah, you can squeeze several high definition cameras into a cubesat, but the moment you realize that you need something other than visible band, temperture control on the ccds, and the power-aperture to beam that stuff down to earth in a meaningful timeframe, you've built 1500lb worth of overhead around your tiny little cubesat and you're back in GOES and NPP land.
The last I looked, the state of remote-sensing algorithms for limb profiling is something between bad and "are you kidding?".
But they are not doing much "remote sensing". All they are doing is recording when a GPS signal is received. That's it. That shouldn't be too hard. The delay between when the GPS should have been received, and was actually received, will tell them the index of refraction of the atmospheric cord it passed through, and from that, a ground computer can calculate the humidity, temperature, and pressure.
That sound you heard is the OP's point whooshing over your head. Limb profiling (what you describe) is a remote sensing technique, and it's not one that works really well.
The problem isn't receiving the signal (well, it's not a problem in this sense though it has challenges of it's own), the problem is analyzing the signal. You have three different variables (all of which vary with altitude to boot), with no way to significantly constrain any one of them - meaning arriving at an accurate value for one (let alone three) is a Very Hard and Poorly Understood problem.
The first question that popped into my mind was did they have a new model that would take data from 100 satellites and produce a more accurate forecast. I don't think that satellites alone are not going to create a more accurate forecast. This reminds me when I was talking to a teacher back in the 80's. He mentioned that at one point it was believed that if we could create a dense enough network of satellites and sensors, we could forecast the weather with great accuracy and for arbitrarily long periods. Theoretically, given an infinite array of sensors, the forecast would be perfect and long range. But then actual science interfered as the work of Lorentz propagated through the ranks. The sensitivity to initial conditions, and the inherent limitations of data collection, made such claims of better forecasting theoretically impossible. I have to think that the current configuration of satellites represents some compromise between cost and benefit. Not to say that more satellites will not provide a benefit. Whoever contracts with the service will be able to claim 'We have better forecasting because we have more satellites', which will help with marketing. It will help push forward the cubesat business and will test out these new technologies, which is of great benefit. And it is an experiment that might succeed in producing useful data that might be able to be put into better models.
"She's a scientist and a lesbian. She's not going to let it slide." Orphan Black
http://www.cosmic.ucar.edu/
http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/04/14/why-cosmic-2-is-a-lot-more-than-nice-to-have/
http://www.cosmic.ucar.edu/workshop_2014/presentations/Session1/uccellini_session1.pdf
http://www.cosmic.ucar.edu/workshop_2014/presentations/Session1/thorpe_session1.pdf
Now lets have an enlightened discussion instead of cynical bull.
http://www.spire.com/weather/ is very vague on exactly what they're doing (other than tracking ships at sea and providing a "data link to the cloud")
GPS occultation using multiple frequencies is a pretty good observational technique. The GPS RO data provides sufficient information to be about the 3rd best source of input to various weather models (after things like ground observations and balloon radiosondes, etc.). Surface winds from satellite scatterometry over the ocean are also useful. One advantage is that GPS-RO is world wide and provides good coverage over oceans where there's not much data to ingest into the models.
COSMIC-2 is a mission with 6 satellites carrying precision GPS receivers and multibeam antennas. http://www.cosmic.ucar.edu/cosmic2/
So here's the issue.. It's unclear whether the SPIRE satellites are using multifrequency GPS (which is needed for this application, because you need to be able to do ionospheric compensation) and whether they are high quality enough receivers to make the measurement. Your basic Novatel GPS that most cubesats carry doesn't have L2 and L5, nor does it have the receiver performance for good RO data. SPIREs website isn't informative on the RO design.. but, for instance, COSMIC-2 has a fairly large phased array GPS antenna (about 2x4 feet) facing fore and aft, and they form a bunch of beams, which I've been given to understand is important in collecting the data needed for weather analysis.
yeah, lots of stuff on COSMIC, but not a heck of a lot on SPIRE.
Is SPIRE doing 3 bands?
What observables is SPIRE measuring?
It will be private data available only through SPIRE? Is SPIRE doing the weather forecasting?
...I personally find it a very interesting Operating Principle that SATNAV signals can be used to "look into" the atmosphere and determine temp, humidity and apparently even wind speed.
It is obvious that this would be a very useful complement of existing sensors (especially due to global homogenous coverage of measurements) on the ground and in space. If it works properly, of course.
And of course the Incumbent Sensor Business (ground radars to imaging satellites) will fight tooth and nail against the New Kid On the Block, because they know the funding cake is rather limited.
But in the spirit of TRUTH, this should not matter. What should matter is the cost/benefit ratio of each sensor principle. And if the COSMIC folks are not lying through their teeth ( I cannot judge this), this approach surely makes a lot of sense.
Why is the Germanic world from Vladivostok to L.A. ahead of the Mohammedic World ? Because we dont deify incumbent practices and because we sometimes at least STOP LYING.
...for non-bull arguments here.