Search found 10 matches

by MarkCohen
October 18th, 2017, 5:30 pm
Forum: General Comments
Topic: Eulerian Approach
Replies: 1
Views: 425

Re: Eulerian Approach

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...
by MarkCohen
June 9th, 2017, 11:08 am
Forum: Users
Topic: Is there a way this can be done?
Replies: 4
Views: 713

Re: Is there a way this can be done?

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 ...
by MarkCohen
June 8th, 2017, 9:59 am
Forum: Users
Topic: Is there a way this can be done?
Replies: 4
Views: 713

Re: Is there a way this can be done?

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 : )
by MarkCohen
October 17th, 2016, 2:57 pm
Forum: Trajectory Model
Topic: Question about back trajectories starting blow PBL
Replies: 5
Views: 543

Re: Question about back trajectories starting blow PBL

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...
by MarkCohen
October 11th, 2016, 11:40 am
Forum: Trajectory Model
Topic: Question about back trajectories starting blow PBL
Replies: 5
Views: 543

Re: Question about back trajectories starting blow PBL

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...
by MarkCohen
August 23rd, 2016, 3:33 pm
Forum: Users
Topic: Surface and near surface trajectories - soliciting input
Replies: 1
Views: 353

Re: Surface and near surface trajectories - soliciting input

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"...
by MarkCohen
August 11th, 2016, 6:48 pm
Forum: Dispersion Model
Topic: Integrate over time series
Replies: 11
Views: 1238

Re: Integrate over time series

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...
by MarkCohen
August 8th, 2016, 1:36 pm
Forum: Dispersion Model
Topic: Integrate over time series
Replies: 11
Views: 1238

Re: Integrate over time series

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:
Picture1.png
by MarkCohen
August 8th, 2016, 11:35 am
Forum: Dispersion Model
Topic: Integrate over time series
Replies: 11
Views: 1238

Re: Integrate over time series

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...
by MarkCohen
August 5th, 2016, 12:57 pm
Forum: Dispersion Model
Topic: Integrate over time series
Replies: 11
Views: 1238

Re: Integrate over time series

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...