Assistance Needed with CLM Model Output for AGB Variable

[yuezhouchen]

Hi all,

I am reaching out for assistance with an issue I'm facing while working with the Community Land Model (CLM). Specifically, I am having trouble with outputting the Above Ground Biomass (AGB) variable.

I understand that to output specific variables, I need to configure the "hist_fincl1" parameter in the user_nl_clm file. I've set this parameter with "AGB," "NPP," and "TLAI" as the desired outputs. However, I was informed that there is no variable named "AGB" available for output.

In my effort to resolve this, I went through the related output TXT file, which lists 1181 output parameters. Despite spending considerable time, I couldn't find any indicators related to above-ground biomass. This is puzzling because I've come across several research papers that utilize CLM for AGB studies, such as the one titled "How can biosphere models simulate enough vegetation biomass in the mountains of the western United States? Implications of meteorological forcing." This leads me to believe that CLM should be capable of conducting above-ground biomass research.

Given this context, I would greatly appreciate any guidance or advice on how to correctly output the AGB variable using CLM. Any suggestions or insights would be immensely helpful.

Attached below is the list of output variables I have consulted:


Thank you in advance for your time and help.

Best regards,CHEN

 

[slevis]

@yuezhouchen
you did the right thing by looking at this text file. I recommend finding all the variables in this list that, if summed, would result in AGB and look at those.

Keep in mind that some variables of interest may appear in this list and be "inactive" and, therefore, not appear in history files. If so, you will find instructions in the User's Guide for adding inactive fields to history.

 

[slevis]

Another clarification:
In simulating the carbon cycle, this model outputs variables as carbon pools, rather than biomass pools. There are rule-of-thumb conversions that you may use to go from carbon to biomass and vice versa.

 

[yuezhouchen]

Another clarification:
In simulating the carbon cycle, this model outputs variables as carbon pools, rather than biomass pools. There are rule-of-thumb conversions that you may use to go from carbon to biomass and vice versa.

Thank you very much for your insightful response. Your reminder has been incredibly helpful. The model I'm using, CLM-BGC, seems to be the reason why my outputs are predominantly focused on carbon stock information. I've contemplated summing various carbon stock factors and then converting them to Above Ground Biomass (AGB), but I'm concerned that this approach might introduce excessive uncertainty into the analysis. My ongoing endeavor is to discover a method that can directly output AGB. As a next step, I intend to explore several different CLM modules to find an effective way for the direct output of actual AGB.