TREFHTMX and TREFHTMN

[cpatrizio]

Hi,

I encountered some unexpected behavior when trying to output daily maximum and minimum near-surface temperature from CESM1.2. I understood that TREFHTMX and TREFHTMN are the relevant variables here, yet when I specify the following settings in user_nl_cam, TREFHTMX and TREFHTMN are both exactly identical to TREFHT:

avgflag_pertape = 'A', 'A'
nhtfrq = 0,-24
mfilt = 1,30
fincl2 = 'TREFHT', 'TREFHTMX', 'TREFHTMN'

My guess is that the problem is related to avgflag_pertape = 'A'. I assumed that if TREFHTMX does in fact store the daily maximum temperature, then taking the daily average would simply yield the daily maximum temperature, since this should not be a function of time. However, this does not appear to be the case, leading me to believe that TREFHTMX is not well-defined when avgflag_pertape = 'A' is specified. Does anyone know what is going on here?

I suppose I may need to specify additional flags to output the maximum and minimum as follows, but this behavior is unexpected/misleading to me:

fincl2 = 'TREFHT', 'TREFHTMX:X', 'TREFHTMN:M'

Thanks for the help.

Casey

 

[hplin]

Hi Casey, TREFHTMX and TREFHTMN and TREFHT are sourced from the same variable and the only difference is in the averaging flag used (X, M, A respectively) -- so if the averaging flag is forced to 'A' in your configuration they would output exactly the same values. Thus the flags are necessary. Hope this is helpful.

 

[slevis]

@cpatrizio @hplin
the land model has similarly named fields: 'TREFMNAV','TREFMXAV'
We define these as the daily min and max of the average 2-m temperature. You could try them, in case they behave as you would have expected. You shouldn't have to specify :M and :X since the min/max is already built into their definition.