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Vertical Levels

When a program uses upper air data (observed or forecasted), a vertical level needs to be specified.  This value can also be set with the level resource.


The level menu lists possible vertical levels.  

        Vertical Level Menu

  1: Sea level                       12: 150 mb                        
  2: Surface                         13: 100 mb                        
  3: 1000 mb                         14: 70 mb                         
  4: 925 mb                          15: 50 mb                         
  5: 850 mb                          16: 30 mb                         
  6: 700 mb                          17: 20 mb                         
  7: 500 mb                          18: 10 mb                         
  8: 400 mb                          19: Tropopause                    
  9: 300 mb                          20: Max wind                      
 10: 250 mb                          21: Whole sounding                
 11: 200 mb                        
  0: Back to previous menu           -1: Exit program                  

Enter the level: 

The items in the level menu can be tailored in the ".lev" menu file.  This will allow the user to toggle items on and off based on model type and forecast time.

Specifying Vertical Levels

The menu lists standard pressure levels but other levels can also accessed.  A specific level can be entered with its value and units:

Value Description
  Special Levels
snd Entire vertical column or whole sounding
sfc Surface level
sfc[100] surface level with 100 mb above surface layer average (parcel trajectory)
sl Sea level
frz Freezing level
lcl Lifted condensation level (LCL)
sea Sea surface
mwnd Maximum wind level
trop Tropopause level
top Top of the atmosphere (not used)
whole Whole atmosphere
top_frz Top most freezing level
lcld_bot Bottom of low cloud layer
lcld_top Top of low cloud layer
lcld_lyr Low cloud layer
mcld_bot Bottom of middle cloud layer
mcld_top Top of middle cloud layer
mcld_lyr Middle cloud layer
hcld_bot Bottom of high cloud layer
hcld_top Top of high cloud layer
hcld_lyr High cloud layer
conv_bot Bottom of convective cloud layer
conv_top Top of convective cloud layer
conv_lyr Convective cloud layer
  Pressure Levels
430mb 430 mb level (pressure)
sfc[100]-500 Surface to 500 mb trajectory with 100 mb mean layer average
850-500mb 850-500 mb layer
sfc-850mb surface to 850 mb layer
p430 430 mb pressure level
p850-500 850-500 mb layer
10mb_ag 10 mb above ground level
10-40mb_ag 10-40 mb above ground layer
  Potential Temperature Levels
310k 310 K potential temperature level (isentropic)
310-330k 310-330 K isentropic layer
k310 310 K isentropic level
k310-330 310-330 K isentropic layer
  Height Levels
2000m 2000 meter level (height)
2000ft 2000 foot level
2000-5000m 2000-5000 meter layer
2000-5000ft 2000-5000 foot layer
h2000 2000 meter level
h2000-5000 2000-5000 meter layer
50m_ag 50 meters above ground level
50ft_ag 50 foot above ground level
50cm_bg 50 cm below ground level
50-200m_ag 50-200 meters above ground layer
50-200ft_ag 50-200 foot above ground layer
50-200cm_ag 50-200 cm below ground layer
  Miscellaneous Levels
97sig .97 sigma level
97-91sig .97-.91 sigma layer
97eta .97 eta level
97-91eta .97-.91 eta layer
2lev 2nd level
2-5lev 2nd-5th level layer
level use the value of the level resource (used in var files)
miss missing level, take first available

For further information about WXP, email technical-support@weather.unisys.com
Last updated by Dan Vietor on May 30, 1998