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Problems in adding CLM history variables

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Yuexuanzi Wang

New Member
Hello,
I want to add a variable named 'DOWNREG' in CLM output history fields.
I have edited the user_nl_clm as hist_fincl1 = 'DOWNREG', and after building case the added variable has appeared in lnd_in.
However, in the h0 output files, the variable exists but has no valid value.
So I wonder what I can do to obtain the valid values?
Any help with this would be appreciated. Thanks a lot.
The complete description in CLM user's guide for 'DOWNREG' is fractional reduction in GPP due to N limitation.
 
O

oleson

Keith Oleson
CSEG and Liaisons
Staff member
If by no valid values you mean zeros, I don't think downregulation is used by default in CLM5. From the technical note:

The implementation of a flexible C:N ratio means that the model no longer relies on instantaneous downregulation of potential photosynthesis rates based on soil mineral nitrogen availability to represent nutrient limitation.
 
Y

Yuexuanzi Wang

New Member
oleson said:
If by no valid values you mean zeros, I don't think downregulation is used by default in CLM5. From the technical note:

The implementation of a flexible C:N ratio means that the model no longer relies on instantaneous downregulation of potential photosynthesis rates based on soil mineral nitrogen availability to represent nutrient limitation.
Click to expand...
Your answer solved my problem. Thank you.
 
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