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iamvegenaut t1_j8vj2h7 wrote

Reply to comment by crimeo in HYSPLIT Air Dispersion model depicting the potential transport of chemical plumes emitted by the East Palestine Chemical Disaster [Ohio]. Simulating February 3-7, 2023 [OC] by apathyEndsNow

Well you asked "plumes of what" and then proceeded to tell us what would likely be there with more specificity than any other source ive seen here or elsewhere has offered, so it seems that was more just a complaint about the vagueness of the model.

HYSPLIT is primarily a model for predicting the movement of localized masses of air that start at a specific point, over a certain period of time, given local conditions/forecast. The only reason I've heard of it is because balloon pilots use it to predict flight paths. I didn't even know it could be used for tracing contaminants. You seem to be suggesting that it can't or shouldn't. But a model doesn't have to be perfect to be useful, and even a crude model is better than no model. I don't know this w/ certainty but I would assume that for gaseous contaminant dispersal, the biggest controlling factor on the dispersal pattern would simply be weather - regardless of gas composition. If that's true then HYSPLIT seems more than sufficient to at the very least say "its probably headed this way", which is all this model appears to be saying.

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crimeo t1_j8vjk7g wrote

> Well you asked "plumes of what" and then proceeded to tell us what would likely be there with more specificity than any other source ive seen here or elsewhere has offered, so it seems that was more just a complaint about the vagueness of the model.

I said what would be in burned vinyl chloride.

That doesn't tell me whether this graphic here is supposed to represent the burned column of smoke (with those things in it) OR cold gas nearer the ground from un burned stuff evaporating off of spilled pools of chemicals.

A distinction I actually made clear in my first comment.

> You seem to be suggesting that it can't or shouldn't.

Not if you don't know whether the gas is cold or burning hot, it can't. Or have any clue as to its general density.

I suspect that the issue isn't that the modeler didn't know any of those things, they almost surely did. But then didn't LABEL them. Making it just a bad graph. Dime a dozen on this subreddit, randomly not labeling crucial information is a tale as old as /r/dataisbeautiful I still don't know which one it is though.

> "its probably headed this way", which is all this model appears to be saying.

No, it's giving specific parts per million in the graphic. And also, as I mentioned as well from the start, it's showing some plumes suddenly disappearing, which I suspected might be "hitting rain clouds and getting knocked out of the air" but was interested in confirmation on.

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iamvegenaut t1_j8vsy5d wrote

i think its only giving a concentration because to model the spatial dispersion pattern of a hypothetical volume of *some contaminant* in air, there has to be a starting concentration of *some contaminant*. it looks like they've used a dust based model, and the standard for quantifying concentrations of stuff in air when the exact composition is unknown (like dust / ash / etc.) is mass per cubic vol. for such hypotheticals the exact values are irrelevant and meaningless, but their relative differences are still useful as a vector.

and I wasn't sure of any of this either at first so i simply clicked the link OP provided to read about the model and its assumptions. There is an impressive amount of documentation available for HYSPLIT. I have learned some cool stuff already. Most of your questions / assumptions could have been addressed by reading the documentation, and doing so would probably even make clear how many of the shortcomings you've identified in the model could be improved. But it doesn't seem like you're interested in learning / contributing / helping bc all you've done so far is use hundreds of words to say nothing more than "youre dumb thats dumb you cant do that", and that seems like a waste of your knowledge

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apathyEndsNow OP t1_j8x8zf2 wrote

Thank you for this concise response. Your explanation is very helpful :)

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crimeo t1_j8xc9f2 wrote

I'm not trying to say "ur dumb" I'm trying to find the answers to the actual questions I asked: was this the hot burning combustion column they were modeling, or was it cold evaporated gases? And optionally: if they measured it for concentrations, did they also measure stuff in it? (maybe maybe not, but had to do SOME measuring, what did it find?)

I will check out the documentation too though, thanks

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