About dry and humid heatwaves

Question

I would appreciate it if someone can assist with a code to calculate the "specific number of heatwaves days where relative humidity > 66% and < 33%". (whereas, a heatwave event is defined as one in which temperatures exceeded the 90th percentile of the daily mean temperature for at least three consecutive days, respectively).

Answer 1

Ok well here is a solution

# temperature percentile
cdo timpctl,90 infile -timmin infile -timmax t2m.nc t2m_pcen90.nc

# mask the temperature
cdo ge t2m.nc t2m_pcen90.nc mask.nc

# Need to make sure we have three consecutive days
cdo --timestat_date last runmean,3 mask.nc mask3.nc
cdo gec,1 mask3.nc heatwave_T.nc 

# Now filter for dry heatwaves, assuming RH is %, change X if fraction
cdo lec,33 rh.nc rhdry.nc
cdo mul heatwave_T.nc rhdry.nc heatwave_dry.nc 

# and same for wet
cdo gec,66 rh.nc rhwet.nc
cdo mul heatwave_T.nc rhwet.nc heatwave_wet.nc 

Each file should have a 1 in it for each location/time when you are in a heatwave according to your definition. Of course the metadata is appropriate for T2m not the index, use NCO to change that if required. I have several video guides that would help with this question, the key one being the one on masking (it doesn't include the running mean part though). Note also that the RH criterion is applied ONLY on the day (no running mean) but that is how you write the definition in your question. Duplicate the running mean part if needed.

ps: In general it is good to show that you have attempted a solution yourself , before asking, SO guidelines are that questions are of a debugging nature, or can be a request for a one-liner, but not coding requests like "write me a code that does X or Y" - I think that is why you were getting downvoted.