HYSPLIT Forum: hysplitbbs.arl.noaa.gov

Posted: **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.

Posted: **November 5th, 2015, 4:31 pm**

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

Posted: **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?

Posted: **November 9th, 2015, 10:31 am**

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

Posted: **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..

Posted: **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.

HYSPLIT Forum: hysplitbbs.arl.noaa.gov

hybrid sigma-pressure levels to altitude in meters

hybrid sigma-pressure levels to altitude in meters

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