Search found 15 matches

by MarkCohen
February 28th, 2020, 1:08 pm
Forum: Users
Topic: HYSPLIT vs ALOHA preferred distance from source
Replies: 1
Views: 442

Re: HYSPLIT vs ALOHA preferred distance from source

The HYSPLIT limitations web page (https://ready.arl.noaa.gov/hypub/limitations.html) has a number of cautions, including the one you mention regarding distances less than 1 km. In the past, HYSPLIT was not recommended for distances less than 1 km from a source because the minimum time step in the HY...
by MarkCohen
November 22nd, 2019, 1:42 pm
Forum: General questions on meteorological data needed for HYSPLIT
Topic: Mixing Height Information and Stability Plots
Replies: 3
Views: 1601

Re: Mixing Height Information and Stability Plots

I've updated the Vmixing tutorial, and associated scripts, and have attached them here. The pdf file is the basic tutorial, and the two zip files contain scripts and results for Windows and for Linux/Mac. Windows scripts are DOS Batch scripts, and Linux/Mac scripts are Korn Shell. They are simple il...
by MarkCohen
October 30th, 2019, 3:31 pm
Forum: General questions on meteorological data needed for HYSPLIT
Topic: Mixing Height Information and Stability Plots
Replies: 3
Views: 1601

Re: Mixing Height Information and Stability Plots

Hi, this is Mark Cohen. Sorry for the delay in responding to this. I will work to package up the scripts and other explanatory material and provide a URL that they can be downloaded from. Hopefully I'll get this accomplished within the next week or so.
by MarkCohen
April 2nd, 2018, 1:08 pm
Forum: Dispersion Model
Topic: MAXPAR/NUMPAR upper limit
Replies: 7
Views: 4927

Re: MAXPAR/NUMPAR upper limit

Hi, sorry it has taken awhile to respond to your last question. In looking at your questions in this thread, I think the key issue is a what a HYSPLIT "particle" really represents. The "particles" being released and tracked in a HYSPLIT simulation (using the default dispersion mode: 3-D particle) sh...
by MarkCohen
March 8th, 2018, 9:26 pm
Forum: Trajectory Model
Topic: Initial heights and mixed layer depth
Replies: 2
Views: 2703

Re: Initial heights and mixed layer depth

Hello! Thank you for alerting us to this issue, and our apologies for taking so long to respond. First, thanks for providing the details that you did, and for very clear explanations (with color coding!). With the information you provided, I was able to attempt the same runs here (i.e., same startin...
by MarkCohen
October 18th, 2017, 5:30 pm
Forum: General Comments
Topic: Eulerian Approach
Replies: 1
Views: 3889

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: 2734

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: 2734

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: 2965

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: 2965

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...