HYSPLIT Forum: hysplitbbs.arl.noaa.gov

Hi, yes, I think that you are "right" in the way you are thinking about this, but I will try to elaborate briefly. The quoted statement you mention is contained in the following reference: Draxler, R. R. and G. D. Hess (1998). "An overview of the HYSPLIT_4 modeling system of trajectories, dispersion...

Hi, one more aspect of this to mention. Note, there is another way to do this, "outside" of the GUI. Basically, you can take any tdump file and edit it to create a simple text file that you can import into your GIS program. Here is what I have done in ArcGIS / ArcMap. There are probably a number of ...

Hi Quaymat321234, I will try to take a look at this as soon as I can, but it will probably be a few days. Thanks for your question and your patience : )

Hi Ren2014, In general, yes, higher-resolution meteorology should usually give more "accurate" trajectories. All things being equal, one could always pick the highest resolution meteorological data available for a simulation. Note that trajectories will stop once they leave the domain of the met dat...

Hi Ren2014, You can absolutely start back trajectories below the PBL, and in fact, this is probably done in the majority of cases in which back-trajectories are run. It basically depends on the problem you are investigating with the back-trajectory. If, for example, you are wondering where the air c...

Hi John, I'm not quite sure what you are asking about. Is it any of these: 1. In a forward "concentration" simulation, what vertical levels should be used for a concentration grid? 2. In a forward "trajectory" simulation, what should the starting height be for a source? 3. In a backward "trajectory"...

Hi Stephen, I'm so glad to hear that it is working for you! Regarding additional data layers, I can give you a few suggestions. (1) Your idea of using Google Earth is a good option. As you know, you can run concplot (Concentration -> Display -> Contours) with the option of exporting Google Earth out...

Hi Stephen,

The concentration grid layer levels are specified when you specify the concentration grid. The image below shows the steps you'd take to do this in the GUI:

Hi Stephen, Couple of thoughts I can offer re: the output you showed. First, the concentration layer that you are collecting data on is from 0-100m which is relatively "thin". You might want to increase this to 200m or 500m or something to see what sort of difference this might make. The particles a...

Not exactly sure what you are trying to do, but I think maybe you could try to do a "backward dispersion" run, where you run the concentration model, but run in backwards in time, like a back-trajectory. In such a simulation, you are in effect doing lots of back-trajectories (i.e., one for each comp...