Environmental modification, ENMOD and our changing climate

Discussion in 'Earth Science' started by subhumn, Feb 15, 2013.

  1. milkweed Valued Senior Member

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  3. Aqueous Id flat Earth skeptic Valued Senior Member

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    One of the ways that concern has been addressed is by posting the raw data collected by the sensor platforms deployed globally. Now anyone who knows how to plot the data is free to see for themselves what it says. While that requires some basic skills in science it certainly does narrow the debate to genuine facts and methodologies. So I think the prospects are very good right now for that kind of discussion. Most of the debate I'm aware of has to do with methods for improving accuracy and resolution, which has been accompanied by upgrades and wider deployment of platforms. You can now see all kinds of ways climate and air quality are being monitored, where the early systems were relatively primitive and coming from just a single station.
     
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  5. Stryder Keeper of "good" ideas. Valued Senior Member

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    According to the philosophy of Chaos theory. a cyclone would only need a butterfly to flap a wing. (although you could always query how the First law of Thermodynamics applies to that since the energy of a butterfly's wing flapping is not proportional to a cyclone, although you could point out it weights apples to orange, since Chaos theory is about the "action" not the "total energy".)
     
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  7. Aqueous Id flat Earth skeptic Valued Senior Member

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    True, but that would apply to the case that the heat energy supplied by the sun is just one butterfly-flap short of a cyclone!

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    Now imagine there's fair weather over Pakistan, but the US plans to send them a national disaster by letting a satellite fall somewhere. Even though it may present a jillion butterfly wings worth of turbulence, it still only amounts to one kajillionth of the amount needed to start a cyclone. Worse, the odds that the disaster will affect the military target is only one in a bazillion.
     
  8. billvon Valued Senior Member

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    The "flap of a butterfly's wing" does not create the energy needed for the cyclone. It just disturbs the local environment, allowing the stored heat of the Sun to begin to create a storm.
     
  9. AlexG Like nailing Jello to a tree Valued Senior Member

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    The whole 'flap of a butterfly's wing' thing means that very complex systems are very sensitive to changes in the initial conditions.
     
  10. Trippy ALEA IACTA EST Staff Member

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    The whole butterfly flaps its wing thing came about because somebody (I think it might have been Feynman, not 100% sure) was running a weather simulation. Weather simulations back then were very boring, they kept producing the same results over and over again from the same starting point. This annoyed them greatly. Whoever it was (Like I said, I think it was Feynman) was interrupted part way through a run. He stopped the run with the intention of coming back to it later. When he restarted the run, rather than starting it from scratch, he resumed from the last data points he had. What he found was that the run deviated from previous runs by increasingly large amounts, going from being a little different to being independent in a relatively short period of time. They got both very excited and very confused by this - they had expected that it would continue along exactly the same path. In the end, they worked out that what caused the error was the fact that the calculator they were using to do the runs printed the data to four decimal places, but stored it internally as six, and it was that difference that caused the deviation. Feynman (or whoever) likened this to "It was as if a butterfly flapping its wings in the amazon had caused a cyclon in New York." (paraphrased).

    Point being that he wasn't saying butterflies could cause cyclones, he was simply relating an analogy to explain the relative size of the error when compared to the relative size of the differences between he runs.
     
  11. billvon Valued Senior Member

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    I very much doubt that Feynmann was that dumb! ANY simulation you run from the same starting point and with the same parameters gives you the same result over and over again. If it doesn't, the simulation is broken. (In the example you used, an anomalous truncation resulted in different outputs.) In addition, long term simulations of anything, from electrical circuits to dynamic simulations of mechanical systems, are very sensitive to initial conditions; a radical change due to a slightly different initial condition is the expected result, not a breakthrough.
     
  12. Trippy ALEA IACTA EST Staff Member

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    Firstly, it was very early in the field. They understood the physics of the system. They knew that their models were complete because the physics is pretty straight forward, but they also knew that their models weren't behaving properly because the results didn't match their expectations. That predictable systems could be driven to chaotic behaviour was the breakthrough.

    Addendum:
    Correction, my recollection was wrong, it was lorenz, not feynman.
     
  13. AlexG Like nailing Jello to a tree Valued Senior Member

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    It was not Fenymann, it was Edward Norton Lorenz

    Cross post with edit.
     
  14. LaurieAG Registered Senior Member

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    Correct AlexG,

    If you want to read about the history of chaos theory and its development with regards to weather formation and other things like the Lorenz Attractor read Ian Stewart's 1989 book 'Does God Play Dice, The New Mathematics of Chaos'.

    In the 'Weather Factory' chapter he writes a paragraph called 'The Butterfly Effect'.

     
  15. iceaura Valued Senior Member

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    One of the major implications of the "discovery" of chaos (more of a recognition of significance: it has always been all around us all the time) is that one cannot reliably cause hurricanes or similar vents by dropping satellites or making other small inputs at sensitive places - because errors of calculation and input dimensions too small for you to prevent or even measure can be amplified to arbitrary size and influence, and change the results beyond your capability to foresee.

    Because the mechanisms involved are full of non-linear positive feedback loops, the ability to predict the weather consequences of dropping a satellite are inversely correlated with the ability to cause them. The ability to predict requires that small and uncontrolled and unobservable variances in the input and initial conditions be damped, not amplified.
     
  16. Trippy ALEA IACTA EST Staff Member

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    I don't know what your point is here. Look again at what I said (which is what Alex agreed with, give or take the correction) and then have another look at the second image you attached and read its caption just a little closer.
     
  17. LaurieAG Registered Senior Member

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    How about reading the book.

    The difference was due to Lorentz restarting with only the 3 decimal places (.506) that were printed not the 6 decimal places used in the calculations (.506127). The actual difference was .000127 and as the number of decimal places used in the calculations increase the expected variation would decrease accordingly.

    Incidentally the following appeared in The Australian newspaper today.

     
  18. iceaura Valued Senior Member

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    No. The discovery was that even decimal place variations too small to small to perceive or be employed by any known computer could results in arbitrarily large differences in outcome within times of ordinary interest, even qualitatively different outcomes (hotter where it should be colder, etc.)
     
  19. LaurieAG Registered Senior Member

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    iceaura, what about integers?

    Just below Figure 57 Ian Stewart writes the following.

    If Lorenz had run the same calculation 100 times from start to end with the same parameters he would receive identical results each time on the same computer. That is what computers are made for. If he ran the calculation on different computers with decimal places of 6, 60, 600, 6,000, 60,000 or 600,000 he would get the same results from running the same calculation 100 times on each different computer but would expect that, as the number of decimal places increased, the actual data/plot produced from each different computer would diverge at some point along the plot made with the highest number of decimal places. If the results of the data/plot were integers he would see that all of the plots were the same regardless of how many decimal places were used. It is part and parcel of the derivation of calculus, discrete maths and computer science.

    There are limitations in the models used and the accuracy, volume and distribution of the data collected limit the accuracy of any form of climate prediction/projection algorithm to not much more than a couple of days to a week at the most. This is not chaos theory but a reflection that even basic models with limited input can be just as accurate or inaccurate as complex models with massive amounts of input.

    A fellow employee, who lived on a farm, once told me in early spring that it was going to be a wet summer because the cows and sheep were having twins and they only do that when they have a good expectation that there will be enough grass to feed. As it turned out the cows and sheep were right.

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  20. Trippy ALEA IACTA EST Staff Member

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    Gosh...
    It's almost like I have read the book (okay, so the print out was three, not four, and I got Lorenz and Feynman mixed up, mea culpa).

    How about actually reading peoples posts before you waste their bandwidth?
     
  21. oakley Registered Member

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  22. iceaura Valued Senior Member

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    That is chaos theory, or at least the basic observation behind it: that very small changes in input data are amplified, not averaged out or otherwise suppressed, by some kinds of physical systems (those with greater than unity exponentially reinforcing feedback loops). It doesn't fundamentally matter how accurately or thoroughly one collects data in such systems - a certain minimum of error in the data is ineradicable, on basic physical principles, and any size error can produce any size or kind of change in the events of the future, in these systems. Weather is one of them.
     

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