Are concentration values needed to run dispersion models?

[lmeade1]

Hello, my name is Eddie Meade. I am a graduate research student at Towson University. We have several air filter samples that we are doing chemical analysis on and are looking to use the HYSPLIT model to correlate the compounds that we are finding on the samples and in the air mass to meteorological data. Essentially, we want to be able to run a forward and backward dispersion model for the dates that we took our samples. I know that HYSPLIT has the ability to run these dispersion models, but do we need to have concentration values for the samples in order to run the model? Or is it just the meteorological data that is required? I ask because we have hundreds of compounds on the samples, all in varying concentrations, so I am unsure of the best way to proceed if the model needs compound specific information in order to do the forward and backward dispersion. Any help or input would be greatly appreciated.

[glenn.rolph]

HYSPLIT does not need compound specific information in order to run a forward or backward dispersion simulation assuming there is no chemical transformation taking place. However, in order to properly model your chemical species transport you will need to define a particle or particles with sizes appropriate to the particles (or gases) you are trying to model in the CONTROL file. These "particles" you define can be particles that have a settling velocity or can be represented as a non-depositing gas, depending on how you define them. If the species you are trying to model can be represented on one particle, you could just define one particle size and model it.

[lmeade1]

Alright, that helps. So the model should be able to run samples ranging in size from 100 to 250 nanometers?

[glenn.rolph]

Yes, you specify the particle sizes in the CONTROL file. Details can be found in the PC help file C:/hysplit4/html/S314.htm