Converting output of dispersion model into vertical profile of chemical concentration at different heights

Post questions, comments and links to research (research papers, web sites, etc) involving HYSPLIT and chemicals in the atmosphere. This section is also to facilitate collaborations between researchers involved in chemical transport and dispersion.
Post Reply
GarySutlieffUoB
Posts: 2
Joined: March 22nd, 2021, 11:21 am
Registered HYSPLIT User: No

Converting output of dispersion model into vertical profile of chemical concentration at different heights

Post by GarySutlieffUoB »

I am looking at the detection of hazardous chemicals using satellites, and I'm running a simulation of atmospheric transmission/absorption to determine whether a given chemical could be detected using the Reference Forward Model, or RFM. One of the inputs this model requires is an atmospheric profile for each gas present in the simulation. These profiles take the form of a specified grid of heights within a certain area (in the case of the target chemical this area is a 1x1x1 km box starting at ground level) followed by another grid of values, this one specifying concentration (in ppmv) at each of the heights specified in the height grid. I'm wondering how to get the results output by the dispersion model (I'm using the online unregistered version since I'm computing with archive data from the date of a past incident, so that I have something to compare to) into a format that I can use in the Reference Forward Model.

I realise that my questions hinge quite a lot both on knowledge of the RFM as well as HYSPLIT, so if this isn't the right place to ask, by all means let me know, but I'm hoping someone can provide the guidance I need. There are also some gaps in my understanding of HYSPLIT since I'm very new to using it in any capacity, so any guidance that might move me in the right direction would also be useful.

My questions are these:
- Do the outputs from the dispersion model contain details of the concentrations at different heights, or just one value for the averaged concentration up to a certain height? As I understand from looking at the plots produced by the model it should be the latter, but the former is what I require, though I'm not sure how to extract that information from the outputs if it is present.
- If information on the concentrations of the particles at different heights is part of the output, what's the best way to access and retrieve that data? I'm currently considering using ArcMap since one of the two options I'm offered for output data is a set of GIS shape files, though ArcMap has proven difficult in the past, so if there is a way to open the raw data, would this be practical? I also have access to R, which I hear HYSPLIT can run in, so would that also suit my needs if I was trying to extract this kind of information?
alicec
Posts: 284
Joined: February 8th, 2016, 12:56 pm
Registered HYSPLIT User: Yes

Re: Converting output of dispersion model into vertical profile of chemical concentration at different heights

Post by alicec »

  • Do the outputs from the dispersion model contain details of the concentrations at different heights, or just one value for the averaged concentration up to a certain height? As I understand from looking at the plots produced by the model it should be the latter, but the former is what I require, though I'm not sure how to extract that information from the outputs if it is present.
The output can provide concentration vertical profiles.
Horizontal and vertical resolution of the output concentrations are user defined.
https://www.ready.noaa.gov/hysplitusersguide/S313.htm

If you are running through the web you will not have so much flexibility in defining the concentration grid.
Most of the web applications assume users just want a single level. Volcanic ash provides multiple levels. I would
recommend installing your own version of HYSPLIT so you can take advantage of all its features.
  • If information on the concentrations of the particles at different heights is part of the output, what's the best way to access and retrieve that data? I'm currently considering using ArcMap since one of the two options I'm offered for output data is a set of GIS shape files, though ArcMap has proven difficult in the past, so if there is a way to open the raw data, would this be practical? I also have access to R, which I hear HYSPLIT can run in, so would that also suit my needs if I was trying to extract this kind of information?
The concentration output files are binary files and their format is described here.
https://www.ready.noaa.gov/hysplitusersguide/S363.htm
HYSPLIT distribution comes with a con2asc utility which will convert these files into ascii text files.
There are some other utilities such ash xtrct_stn and con2stn which will extract time series of concentrations or concentrations at specific locations.

There is a pretty active HYSPLIT community that uses R. So there is quite a lot of R code available for running HYSPLIT and reading output files.
splitR is one popular package.
https://github.com/rich-iannone/splitr

There is also some python code which will read the concentrations files into an xarray DataSet.
https://github.com/noaa-oar-arl/monetio ... tio/models
GarySutlieffUoB
Posts: 2
Joined: March 22nd, 2021, 11:21 am
Registered HYSPLIT User: No

Re: Converting output of dispersion model into vertical profile of chemical concentration at different heights

Post by GarySutlieffUoB »

Thank you very much for this advice, that is all very helpful! I'll be sure to download the client for HYSPLIT and see what progress I can make with that! Especially thank you for your explanation of the outputs in more detail and for recommending HYSPLIT for R, since I have some experience with R and might find that beneficial.
Post Reply

Return to “Chemicals”