hybrid sigma-pressure levels to altitude in meters

Post any praises for the work of the HYSPLIT Developers and the products they make available to the public or any helpful criticisms so that we can do a better job of providing quality products.
Post Reply
cobzac
Posts: 5
Joined: September 3rd, 2015, 4:43 pm
Registered HYSPLIT User: No

hybrid sigma-pressure levels to altitude in meters

Post by cobzac » November 5th, 2015, 12:34 pm

Is there a way (formula) to convert hybrid sigma-pressure levels to altitude in meters? What I am trying to do is to get wind direction and speed at certain height (meters) from file *gdas0p5.

ariel.stein
Posts: 629
Joined: November 7th, 2012, 3:14 pm
Registered HYSPLIT User: Yes
Contact:

Re: hybrid sigma-pressure levels to altitude in meters

Post by ariel.stein » November 5th, 2015, 4:31 pm

The program profile.F should help you get the variables profiles as a function of height.

cobzac
Posts: 5
Joined: September 3rd, 2015, 4:43 pm
Registered HYSPLIT User: No

Re: hybrid sigma-pressure levels to altitude in meters

Post by cobzac » November 6th, 2015, 6:15 pm

ariel.stein wrote:The program profile.F should help you get the variables profiles as a function of height.
I only have executable profile.exe where I can find source code to edit it and compile? Is there any documentation on the format of gdas files so I can write my program to extract desired values at desired height and long and lat?

ariel.stein
Posts: 629
Joined: November 7th, 2012, 3:14 pm
Registered HYSPLIT User: Yes
Contact:

Re: hybrid sigma-pressure levels to altitude in meters

Post by ariel.stein » November 9th, 2015, 10:31 am

As a start, you could run the executable and see if it meets your needs

cobzac
Posts: 5
Joined: September 3rd, 2015, 4:43 pm
Registered HYSPLIT User: No

Re: hybrid sigma-pressure levels to altitude in meters

Post by cobzac » November 9th, 2015, 1:42 pm

ariel.stein wrote:The program profile.F should help you get the variables profiles as a function of height.
so I tried and it gave the variables profiles as a function of pressure, how to convert pressure to height in meters?

Code: Select all

        PRSS  MSLE  UMOF  VMOF  TPP6  SHTF  DSWF  SPH2  U10M  V10M  T02M  TCLD  PBLH  LHTF  USTR  RGHS  PTRO 
         hPa                      mm  W/m2  W/m2         m/s   m/s    oC     %     m  W/m2  cm/s     m       
   970   970  1016  3E-2  1E-1     0   118   613  1E-2  -1.6  -4.6  25.1     0  1202  32.0  28.9  1E-1   109                   
        3D Fields 
        TEMP  UWND  VWND  WWND  SPHU  PRES     TPOT  UWND  VWND               
          oC   m/s   m/s  mb/h  g/kg             oK  W->E  S->N               
   970  24.4  -1.3  -4.0     0   7.3   969    300.3  -1.3  -4.0               
   965  23.7  -1.2  -4.8  -2.9   7.3   965    299.9  -1.2  -4.8               
   959  23.2  -1.6  -4.5  -3.0   7.1   956    300.1  -1.6  -4.5               
   953  22.4  -1.6  -4.3     0   7.1   951    299.8  -1.6  -4.3               
   
and so on..            

ariel.stein
Posts: 629
Joined: November 7th, 2012, 3:14 pm
Registered HYSPLIT User: Yes
Contact:

Re: hybrid sigma-pressure levels to altitude in meters

Post by ariel.stein » November 9th, 2015, 4:30 pm

The gdas 0.5 degree dataset has the following 55 hybrid sigma-pressure Levels
-----------------------------------------------------------------------
0.9999, 0.9947, 0.9886, 0.9817, 0.9739,
1.9648, 1.9544, 2.9425, 4.9288, 6.9132,
8.8954, 11.875, 16.853, 21.827, 26.799,
33.769, 41.735, 49.699, 59.660, 69.619,
80.576, 91.531, 102.49, 113.44, 123.39,
133.35, 143.30, 151.26, 157.22, 162.18,
165.15, 166.12, 165.09, 162.07, 157.05,
150.04, 142.02, 132.01, 122.01, 111.00,
99.002, 88.000, 78.000, 68.000, 59.000,
52.000, 45.000, 39.000, 34.000, 29.000,
25.000, 21.000, 18.000, 15.000, 13.000

A pressure level is defined as: P = A + 0.B*PRSS,
where PRSS is the surface pressure and A.B is defined as the level, so for instance for level 13: A.B=16.853; A=16 and B=853 ; then P = 16+0.853*PRSS

Finally you can take the pressure levels and use the hypsometric equation and get the equivalent height.

Post Reply