selecting a range of vertical levels

Added by Rob Nicholas about 13 years ago

Is there a way select a range of vertical levels? For date ranges we have seldate, for horizontal regions, we have sellonlatbox, but it seems there's nothing analogous for vertical levels -- sellevels requires a list of the exact levels.

The particular problem I have is that the various CMIP3 models use different sets of levels for ocean depths. I'd like to select a range of depths, say 0-700 m, without needing to know the particular levels for each model ahead of time.

In lieu of an operator for this, can anyone suggest a hack that might accomplish the same thing?

Thanks!
Rob

Replies (3)

RE: selecting a range of vertical levels - Added by Ralf Mueller about 13 years ago

You could still use sellevel. Lets say, you have a variable with 10 levels:


[ram@thingol:~/data/icon]cdo sinfov  -selname,T icon_oce.nc                      [9:36:14|12-01-27]
cdo sinfon: Started child process "selname,T icon_oce.nc (pipe1.1)".
   File format: netCDF2
    -1 : Institut Source   Name        Time Typ  Grid Size Num  Levels Num
     1 : unknown  unknown  T           var  F32     20480   1      10   1
   Horizontal grids :
     1 : unstructured > size      : dim = 20480  nvertex = 3
                        clon      : min = -3.14159265  max = 3.14159265  radian
                        clat      : min = -1.55288464  max = 1.55289374  radian
                        available : xvals yvals xbounds ybounds
   Vertical grids :
     1 : depth_below_sea        m : 25 100 250 500 875 1400 2100 3000 4000 5000 
   Time axis :  1 step
  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss
  2076-04-17 00:00:00
cdo(2) selname: Processed 204800 values from 28 variables over 1 timestep. ( 0.00s )
cdo sinfon: Processed 1 variable over 1 timestep. ( 0.00s )

Then you can use sellevel with an integer range like 25/900:

cdo  -sellevel,25/900 -selname,T icon_oce.nc sellevel.nc

There will some warnings, because of missing levels, but you can ignore this. Thre resulting file looks wuite good:


[ram@thingol:~/data/icon]cdo sinfov sellevel.nc                                  [9:39:05|12-01-27]
   File format: netCDF2
    -1 : Institut Source   Name        Time Typ  Grid Size Num  Levels Num
     1 : unknown  unknown  T           var  F32     20480   1       5   1
   Horizontal grids :
     1 : unstructured > size      : dim = 20480  nvertex = 3
                        clon      : min = -3.14159265  max = 3.14159265  radian
                        clat      : min = -1.55288464  max = 1.55289374  radian
                        available : xvals yvals xbounds ybounds
   Vertical grids :
     1 : depth_below_sea        m : 25 100 250 500 875 
   Time axis :  1 step
  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss
  2076-04-17 00:00:00
cdo sinfon: Processed 1 variable over 1 timestep. ( 0.00s )

Operator parameters are described here.

RE: selecting a range of vertical levels - Added by Mark Payne almost 4 years ago

This question is rather old (9 years) but it seems to be the only resource I can find on the topic today. The answer proposes the specification of an integer range as follows:

cdo -sellevel,25/900 -selname,T icon_oce.nc sellevel.nc

However, this only works if the levels themselves are also integers. As soon as you get a layer that is e.g. 33.3333, it gets overlooked by this approach (also in the most recent versions of CDO). Is there now any way to specify a range as the OP asked? Or could this be added as a new operator?

Cheers,

Mark

RE: selecting a range of vertical levels - Added by Uwe Schulzweida over 3 years ago

This feature will be available in the next CDO release 2.0.0. The operator select will then have the key levrange to select the level range:

cdo select,levrange,25,900,name=T icon_oce.nc sellevel.nc

Cheers,
Uwe

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