Hi,

your question is not explicit enough, be specific.

nevertheless, if you want to isolate certain events from a large dataset for composite analysis.

Check “ cdo selmon/selyear/ etc.

cheers.

Hello Akinsanola,

thank you for your commitment

Just i want to make composite for two netcdf files, like olr with RMM!

cheers,

A simple example with cdo.

Let's assume you have a monthly netcdf data of OLR from 1970 - 2017 named "olr.mon.mean.nc". And your task is to isolate wet years (1980, 1995, 2002) and dry years (1977, 1982, 1989, 2015) for only June - September (JJAS) months and perform a year mean (i.e. mean of JJAS for each year).

##code

cdo -yearmean -selyear,1980, 1995, 2002 -selmon,6/9 olr.mon.mean.nc OLR_wet_yearmean_JJAS.nc

cdo -yearmean -selyear,1977, 1982, 1989, 2015 -selmon,6/9 olr.mon.mean.nc OLR_dry_yearmean_JJAS.nc

OLR_wet_yearmean_JJAS.nc and OLR_dry_yearmean_JJAS.nc are the composite for wet and dry years respectively.

For more, read the cdo manual

https://code.mpimet.mpg.de/projects/cdo/embedded/cdo.pdf

cheers

@Akinsanola,

I Appreciate all you did, Yes of course we can do composite if we know the specific situation /as you said, knowing specific dray and wet years/.

But I my case, I want to make OLR composite by MJO phase to know the systematic OLR anomalies associated with MJO phase during JJAS seasons! Just to extract the enhanced phase for these specific seasons/ in order to pick one or two phase which will have significant impact on convection enhancement for a specific region/.

cheers,

Okay.

Check NCL examples.

https://www.ncl.ucar.edu/Applications/mjoclivar.shtml

maybe that can help you.

cheers

@Akinsanola,

Thank you Very much!