correct unit setup in backward dispersion run

[katerina.sindelarova]

Hi,

I'm running Hysplit in backward dispersion (concentration) configuration, using the locations and measured concentrations of I131 at multiple stations in order to estimate possible source location and source term. The unit of measured values is microBq/m3. I'm wondering how should I correctly set up the backward run in order to obtain the right values in the output file?

Please note that I'm not using the source-receptor matrix option in Hysplit. I perform multiple model runs for each station acting as a source and extract values from the output files which are then used for inversion outside Hysplit.

The backward runs seem to be working well. Results of source location estimation look reasonable after the inversion. However, the values for source term estimate seem to be too low. At the moment I assign the emission rate to 1 in the CONTROL file. But I'm not sure how the model deals with the units and what are the values it gives at the output in this case?

Any suggestions will be appreciated,
Katerina

[ariel.stein]

As you have your run currently set up, the output units for the backward dispersion will be in [emission units/m3]. I would suggest you take a look at the section of our training material dealing with source attribution. http://www.ready.noaa.gov/documents/Tut ... _back.html
Also, you can read the following exchange in this Forum where we helped a user to set up his run for an inverse modeling application like yours. viewtopic.php?f=28&t=900&p=2806&hilit=footprint#p2458

[blake.arpansa]

I had a similar enquiry to the one above.
I have read through some of those links recommended, but I am still somewhat confused on the right course of action.

I'm looking to backtrack from some detector locations measuring radionuclides.
The stations have a 12 hour detection period.
In this case should the emission rate be set to (1/12) per hour, in order to simulate a 'unit' detection, which could then be used to create the dilution map of possible source?

Thanks for your help.

[ariel.stein]

Yes, you can set up the emission to 1/12 and emit for 12 hours.