Altering the CONTROL file for Matrix Calculation

[reshmarpunjabi]

I am trying to use HYSPLIT to calculate multiple forward trajectories emanating from a small region (i.e., a residential complex). However, I am unable to generate more than 2 trajectories using MATRIX: the initial conditions specified in the CONTROL file have latitude and longitude rounded to 2 decimal places. Since my source region is very small, I would like to specify the initial conditions to 3 decimal places and beyond.

I tried changing the permission of the CONTROL file to read-only, but the file is overwritten and regenerated (with only 2 decimal places) every time the MATRIX program is run.

I would like to modify the CONTROL file or source code to allow for additional decimal places. Is this possible? Any advice would be greatly appreciated.

[barbara.stunder]

There is information about the Matrix in the Tutorial section 12.5 at
https://ready.arl.noaa.gov/documents/Tu ... _recp.html

Do a regular (non-matrix) run with the source latitude/longitude using 3 or more digits. Then add the 2nd and 3rd latitude/longitude locations for the matrix run.

[reshmarpunjabi]

Thank you very much for your response. I have tried doing the same, and referring to the given tutorial, however I still end up with the same result (i.e. the initial conditions being rounded off to 2 decimal places).

Is there any other means of approaching the issue?

[alicec]

In the matrix run, a pre-processor program latlon is called which re-writes the CONTROL file to have more source points.

1 You can use that pre-processor program to write your CONTROL file with lots of points and then edit it to put the lat and lon with 3 decimal
places. Then do a regular run with that CONTROL file. (In the GUI you can retrieve a CONTROL file using the retrieve button at the bottom).
If you retrieve that CONTROL file then it will load it into the GUI.

2. Just do a regular run and enter the number of starting locations that you need yourself in the GUI.

3. write your own pre-processor program in the language of your choice to write out all the starting locations that you need in the CONTROL file.

Note that if you are trying to model many trajectories that close together you might want to consider what the resolution of your
meteorological data is.

[reshmarpunjabi]

Thank you for your reply.

Since I need about 100 starting points in a very small area, is there any way to bypass the need of manually writing out the latitude and longitude of the 100 points? I was hoping using the matrix feature would increase efficiency and effectiveness in this respect. Kindly do let me know. Thanks!

[alicec]

The CONTROL file is simply a text file so you can write your own program to write out the points and insert them into the CONTROl file.