CDO

Hi,

I'd like to apply the 24-hour difference filter to the 6-hourly reanalysis meridional wind velocity. The filter is as simple as v1df = (v[t+24hr]-v[t])^2. In other words, you basically shift the original data by 1 day, subtract the original data from the time shifted data, and square the difference. I use shifttime and sub/sqrt, however the resultant field is all zero:

cdo shifttime,1day ifile.nc tmp.nc
cdo sqrt -sub tmp.nc ifile.nc ofile.nc