## Size of puffs

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amgottseg
Posts: 2
Joined: October 9th, 2019, 10:06 am
Registered HYSPLIT User: No

### Size of puffs

Hello

I have been making visualizations of particle dispersions. I'd like to try making visualizations of puffs as well. In the PARDUMP file, where is the information on the size of the puff? Such as radius? I would think that SIGW, SIGH, and SIGV would be the radii across x,y, and z directions, but these numbers always seem to range between -0.5 and 2, and don't significantly change over time. How can these numbers be negative? Any explanation is very appreciated!
alicec
Posts: 255
Joined: February 8th, 2016, 12:56 pm
Registered HYSPLIT User: Yes

### Re: Size of puffs

SIGH and SIGW are the relevant parameters for the puffs.

SIGH is the horizontal puff width.
SIGW is the vertical width if you are using 3d puffs (initd=1 or 2).

SIGV is only relevant for particles, not puffs.

See below some example output from par2asc from a 3d puff run.
This was using nams meteorology.

The SIGH and SIGW are in bold in the first two lines.
Note that the value of SIGV is not used for pure puff dispersions.

If you are getting negative numbers in the SIGW, then you are probably using
particle mode in the vertical (initd=3 or 4). In that case the SIGW is representing the
turbulent velocity in the vertical, which can be negative.

Record 1: MASS(1:NUMPOL)
Record 2: TLAT,TLON,ZLVL,SIGH,SIGW,SIGV
Record 3: PAGE,HDWP,PTYP,PGRD,NSORT
9260 1 19 2 7 0 0
0.764E+02
38.954 -90.697 645.837 1565.959 0.007 1001.000
63 1 1 1 1
0.764E+02
38.948 -90.698 643.975 1545.469 0.007 1001.000
62 1 1 1 2
0.764E+02
38.942 -90.700 641.899 1524.935 0.007 1001.000
61 1 1 1 3
0.638E+01
39.366 -90.343 990.339 6902.289 0.018 0.000
121 1 1 1 4
0.638E+01
39.360 -90.334 989.963 6892.970 0.018 0.000
121 1 1 1 5
0.638E+01
39.374 -90.339 990.684 7069.917 0.018 0.000
121 1 1 1 6
0.638E+01
39.375 -90.337 991.118 7032.935 0.018 0.000
121 1 1 1 7
0.638E+01
39.366 -90.329 989.984 6861.437 0.018 0.000
121 1 1 1 8
0.638E+01
39.361 -90.326 989.407 6795.729 0.018 0.000
121 1 1 1 9
0.638E+01
39.356 -90.322 990.084 6712.469 0.018 0.000
amgottseg
Posts: 2
Joined: October 9th, 2019, 10:06 am
Registered HYSPLIT User: No

### Re: Size of puffs

And what is the unit for SIGH when it represents horizontal width? Meters?