Avoid problems with particles reaching the stratosphere

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antonio.cervone
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Avoid problems with particles reaching the stratosphere

Post by antonio.cervone »

Roland recommended to fix the timestep in order to avoid big reductions of it due to particles moving under faster winds in the stratosphere.
Would it be a good option to reduce the "top of the model" option in the setup to avoid this problem?
christopher.loughner
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Re: Avoid problems with particles reaching the stratosphere

Post by christopher.loughner »

This is not recommended. Lowering the model top for this scenario will cause pollutants that should be transported into the stratosphere to stay below the model top resulting in a high bias in particle concentrations just below the model top. These particles being prevented from crossing the model top will also be diluted at a slower rate due to lower wind velocities.
antonio.cervone
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Re: Avoid problems with particles reaching the stratosphere

Post by antonio.cervone »

Thank you.
My naive idea was that particle reaching the top of the model would "die" just like particles reaching the horizontal ends of meteorological data.
Is there an option to do so?
christopher.loughner
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Re: Avoid problems with particles reaching the stratosphere

Post by christopher.loughner »

For dispersion simulations, particles are reflected off of the model top staying within the modeling domain.

Note that this is not the case for trajectory simulations. A trajectory calculation will stop when it is transported above the model top.
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