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Combining fldmean and maskregion for more than one region

Added by Sanita Dhaubanjar almost 7 years ago

Hi,

Is it possible to combine fldmean and maskregion operators to get regional means for more than one region at once? I am able to specify multiple polygon in maskregion. But when combined with fldmean I get mean for all regions combined. Is there a way to define the fldmean for each region as a new parameter or something similar?


Replies (6)

RE: Combining fldmean and maskregion for more than one region - Added by Ralf Mueller almost 7 years ago

Hi Sanita!

Sorry, but fldmean takes into account all elements of a grid. Hence it cannot identify multiple regions given by a single mask. You might upload some data and your calls so that I can checkm if there is a propper workaround.

cheers
ralf

RE: Combining fldmean and maskregion for more than one region - Added by Sanita Dhaubanjar almost 7 years ago

Hi Ralf,

In attached, the text file has boundaries for two regions of my interest. I want to extract say long term annual totals for the two regions for the entire timeperiod. I can do:
cdo -L -outputtab,date,value -fldmean -maskregion,bndry_r1.txt -timsum -yearsum $ifile>yrLT_r1.txt
cdo -L -outputtab,date,value -fldmean -maskregion,bndry_r2.txt -timsum -yearsum $ifile>yrLT_r2.txt
Then i merge the text files to get long term annual totals for the two regions in one file.

I am wondering if I can do something like save r1_yrLT as one parameter and r2_yrLT as second parameter and then use outputtab after I have run through all the regions. I have multiple .nc file and multiple regions to work with. So with be nice if this could be automated in CDO.

Thanks!

Download all files
bndry_r1&r2.txt (157 KB) bndry_r1&r2.txt
pr_NPL-44i_MPI-M-MPI-ESM-LR_rcp85_r1i1p1_MPI-CSC-REMO2009_v1_day_2006-2016.nc (4.2 MB) pr_NPL-44i_MPI-M-MPI-ESM-LR_rcp85_r1i1p1_MPI-CSC-REMO2009_v1_day_2006-2016.nc

RE: Combining fldmean and maskregion for more than one region - Added by Ralf Mueller almost 7 years ago

could you send both boundary files separately? cannot redo your calls otherwise

RE: Combining fldmean and maskregion for more than one region - Added by Ralf Mueller almost 7 years ago

you could write it in a single cdo call like this 

cdo -L  -cat \
  -chname,pr,pr_regionA -fldmean -maskregion,bndry_r1.txt -timsum -yearsum pr_NPL-44i_MPI-M-MPI-ESM-LR_rcp85_r1i1p1_MPI-CSC-REMO2009_v1_day_2006-2016.nc \
  -chname,pr,pr_regionB -fldmean -maskregion,bndry_r2.txt -timsum -yearsum pr_NPL-44i_MPI-M-MPI-ESM-LR_rcp85_r1i1p1_MPI-CSC-REMO2009_v1_day_2006-2016.nc \
  mergedRegions.nc

this will work unless you don't have multple timesteps. if you want to process multiple years in on call, a sorting of time steps afterwards will be helpful.

output looks like this

cdo infov mergerdRegions.nc                                                                                                                                                                                                                         
    -1 :       Date     Time   Level Gridsize    Miss :     Minimum        Mean     Maximum : Parameter name
     1 : 2011-07-02 12:00:00       0        1       0 :                  22241.             : pr_regionA    
     2 : 2011-07-02 12:00:00       0        1       0 :                  25145.             : pr_regionA    
cdo infon: Processed 2 values from 1 variable over 2 timesteps ( 0.00s 40MB )

hth
ralf

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