Determination of anomalies for Geopotential height
Added by Abubakar Bello about 3 years ago
Kindly assist me, I am trying to calculate the seasonal (JFM, OND and DjF)anomalies of geopotential height over the domain lat -40 -5 and lon 5 to 55 using monthly geopotential values. My years of interest are 1989,1996, 2003 and 2015.
These are my codes
cdo selseas, JFM monthGPH.nc JFM.nc
cdo seasmean JFM.nc Mean_JFM.nc
cdo timmean Mean_JFM.nc L.mean.JFM.nc
cdo sub Mean_JFM.nc L.mean.JFM.nc Ano.JFM.nc
cdo selyear,1989 Ano.JFM.nc ano.JFM89.nc
The ano.JFM89.nc and other years of interest anomalies are all out the grids when I try to plot int in grads.
Can someone help me?
Replies (2)
RE: Determination of anomalies for Geopotential height - Added by Karin Meier-Fleischer about 3 years ago
Hi Abubakar,
you have to take care computing seasons because per default CDO uses DJF, MAM, JJA, SON seasons. For DJF not problem, but you have to change the start month of the season to JAN for JFM and OND. Here is a script. If you have problems furthermore it is more a grads question.
#!/usr/bin/env ksh export CDO_TIMESTAT_DATE=middle export CDO_SEASON_START=JAN # <-- change season start month infile="$HOME/data/CMIP5/atmos/va_Amon_MPI-ESM-LR_historical_r1i1p1_198001-198912.nc" cdo -selseas,JFM -sellevel,100000 $infile JFM.nc cdo -seasmean JFM.nc Mean_JFM.nc cdo -timmean Mean_JFM.nc L.mean.JFM.nc cdo -sub Mean_JFM.nc L.mean.JFM.nc Ano.JFM.nc cdo -selyear,1989 Ano.JFM.nc ano.JFM89.nc #----------------------------------------------------------- cdo -selseas,OND -sellevel,100000 $infile OND.nc cdo -seasmean OND.nc Mean_OND.nc cdo -timmean Mean_OND.nc L.mean.OND.nc cdo -sub Mean_OND.nc L.mean.OND.nc Ano.OND.nc cdo -selyear,1989 Ano.OND.nc ano.OND89.nc #----------------------------------------------------------- export CDO_SEASON_START=DEC # <-- change back cdo -selseas,DJF -sellevel,100000 $infile DJF.nc cdo -selmonth,1 -seasmean -seltimestep,3/29 DJF.nc Mean_DJF.nc cdo -timmean Mean_DJF.nc L.mean.DJF.nc cdo -sub Mean_DJF.nc L.mean.DJF.nc Ano.DJF.nc cdo -selyear,1989 Ano.DJF.nc ano.DJF89.nc
-Karin
RE: Determination of anomalies for Geopotential height - Added by Abubakar Bello about 3 years ago
Hi karim
Thank you for the support, it works perfectly for the seasons JFM and OND but my DJF is not for the same year.