Terrain height

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Paul Saey
Posts: 3
Joined: February 4th, 2013, 7:25 am
Registered HYSPLIT User: Yes

Terrain height

Post by Paul Saey »

Hi,

Roland explained the difference between model terrain height and real terrain height. How can I find out what the model terrain height is for a certain location (where I know the coordinates of)?

Thank you very much!

Paul
Fantine
Posts: 118
Joined: November 8th, 2012, 3:41 pm

Re: Terrain height

Post by Fantine »

One way to get the model terrain height for a certain location is to print out the terrain field of the met data.
Open the profile menu from Meteorology / Display Data / Text Profile tab. Set the file name of the ARL format data, and put in the lat/long, then generate the profile.

For example, below is the profile at 35.5 (lat) and -82.0 (long) generated from captex2_wrf27uw.bin file. The model terrain is 976 m under the variable named "SHGT".

METEOROLOGICAL PROFILE LISTING ...
Meteorological Profile: captex2_wrf27uw.bin
File start time : 83 9 25 0 0
File ending time: 83 9 28 23 0

___________________________________________________
Profile Time: 83 9 25 0 0
Used Nearest Grid Point ( 33, 11) to Lat: 36.50, Lon: -82.00
2D Fields
SHGT PRSS TPP1 DIFR PBLH USTR DSWF SHTF LHTF T02M U10M V10M WDIR WSPD
m hPa mm m cm/s W/m2 W/m2 W/m2 oC m/s m/s deg m/s
918 976 918 0 0 0 10.3 0 -15.3 -8.0 5.0 -1.2 2.0 157.9 2.3
3D Fields
PRES TEMP UWND VWND WWND DIFW SPHU TKEN DIFT TPOT WDIR W
oC m/s m/s mb/h g/kg J/kg oK deg
917 917 7.7 -2.0 1.5 4.9 1E-5 5.3 0 0 287.9 136.1 2.5
915 915 9.0 -2.9 2.9 6.8 -1E-5 5.2 0 0 289.4 144.9 4.2
913 913 9.1 -3.1 3.1 7.3 -2E-5 5.0 0 0 289.8 144.6 4.3
Fantine
Posts: 118
Joined: November 8th, 2012, 3:41 pm

Re: Terrain height

Post by Fantine »

Here is the screenshot (attached):
Image
Attachments
Capture.PNG
Paul Saey
Posts: 3
Joined: February 4th, 2013, 7:25 am
Registered HYSPLIT User: Yes

Re: Terrain height

Post by Paul Saey »

Thank you very much Fantine! Works fine.

Just an additional question: I looked at your example (36.5 -82). In the Metfile it gives an altitude of 976m. However, in GoogleEarth, this coordinate gives 1212m. Does this mean the Met model terrain height does not necessarily needs to be higher than the real terrain height?

Thanks again!

Paul
Fantine
Posts: 118
Joined: November 8th, 2012, 3:41 pm

Re: Terrain height

Post by Fantine »

Hi Paul,

it is not always one higher than another. The terrain height used in HYSPLIT usually comes from the met data. It depends on what terrain dataset the met model uses and how it was processed. So, it may be the model terrain lower than the real terrain height (like the example, in that I selected a location on a mountain ridge).

If the terrain is not available in the met file, HYSPLIT will use the static file which is set in the ASCDATA.CFG file.
Paul Saey
Posts: 3
Joined: February 4th, 2013, 7:25 am
Registered HYSPLIT User: Yes

Re: Terrain height

Post by Paul Saey »

Thanks Fantine!

Paul
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