CDO

I am currently analysing climate data and attempting to find yearly maximum values as well as the days on which they occur. I am working with large netCDF that consists of 3-hour or daily tiem resolution.

I am able to use CDO for most of this, but am having issues finding a way to obtain the time indices corresponding to the maximum values obtained using CDO.

For example, if I am working with 30 years of 3-hourly temperature data I may do something like this...

1. Convert to daily time resolution by getting daily maximums
cdo daymax temp_30yr_3hr.nc temp_30yr_daymax.nc
2. Obtain grids of the maximums for every year
cdo yearmax temp_30yr_daymax.nc temp_30yr_yearmax.nc

At this point I should have a netCDF file with 30 time steps(one for each year) and each of these steps should be made up of the maximum temperatures that were observed over the whole year at each point.
I need help creating a netCDF that has the same dimesions as temp_30yr_yearmax.nc and indicates the days of the year at which the maximum temperatures were observed on. Ideally this would be done using integer values that count the days since the start of the year (as opposed to actual dates).

Any advice is appreciated.