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Compound event

Added by Michael Akin almost 2 years ago

Hello,

I would appreciate it if someone could assist me with a CDO code to calculate the simultaneous occurrence of an event. Using maximum and minimum daily temperature, I want to compute a compound heatwave event of "at least three consecutive days with simultaneous occurrence of Tmax ⩾ 90th percentile and Tmin ⩾ 90th percentile". Thank you.


Replies (4)

RE: Compound event - Added by Karin Meier-Fleischer almost 2 years ago

Hi Michael,

I'm not quite sure but I would do something like

cdo -chname,ta,tamin -timselmin,3 infile.nc tmin3.nc
cdo -chname,ta,tamax -timselmax,3 infile.nc tmax3.nc
cdo -chname,ta,ta90 -timselpctl,90,3 infile.nc tmin3.nc tmax3.nc tpctl90.nc

cdo -O -merge tmin3.nc tmax3.nc tpctl90.nc tmp.nc

cdo -expr,'heat=((tamin >= ta90) && (tamax >=ta90))?1:0' tmp.nc outfile.nc

RE: Compound event - Added by Michael Akin almost 2 years ago

Thank you so much, Karin.

This may be a silly question. What if I want the 90th percentile of the Tmax and Tmin based on a "5-day window (5-day moving window centered on each calendar day)"? How do I include that?

RE: Compound event - Added by Karin Meier-Fleischer almost 2 years ago

Have a look at

https://code.mpimet.mpg.de/projects/cdo/embedded/cdo.pdf#subsection.2.8.13
https://code.mpimet.mpg.de/projects/cdo/embedded/cdo.pdf#subsection.2.8.14

In the commands from above change the nset=3 to nset=5, e.g.

-timselmin,5
-timselmax,5
-timselpctl,90,5

RE: Compound event - Added by Michael Akin almost 2 years ago

Thank you Karin.

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