Question about transient CO2 concentration under future climate?

[mengqi]

Hi,

I am working on regional-scale simulation under SSP-585 using CLM5. However, I found that for the current simulation, CO2 concentration is constant. Thus, it may lead to an error.

I was wondering how I use transient CO2 concentration when I run CLM5. Could anyone give some insights about this? Thanks!

 

[oleson]

The xml variables for CO2 should be set properly when you specify an SSP compset, e.g., SSP585, as well as nitrogen and aerosol deposition.

 

[mengqi]

The xml variables for CO2 should be set properly when you specify an SSP compset, e.g., SSP585, as well as nitrogen and aerosol deposition.

Thank you, @oleson.

I am working on running SSP585 using the 'I2000Clm51BgcCrop' compset. Specifically, I am using CLM1PT mode for adding SSP atmosphere driving (not including CO2). By the way, I did not use "anomaly forcing" option.

If so, I am not sure when I specify an SSP compset (e.g., SSP585), then I could use CLM1PT mode for adding SSP atmosphere driving.

Thank you for your insights in advance!

 

[oleson]

I suggest creating a separate case using the SSP585 compset and then comparing the env_run.xml file with your I2000 case to see what changes there are in the CO2, etc. variables.

 

[mengqi]

I suggest creating a separate case using the SSP585 compset and then comparing the env_run.xml file with your I2000 case to see what changes there are in the CO2, etc. variables.

Thank you, @oleson!

According to your advice, I run a new case using the 'ISSP126Clm50BgcCrop' compset. For clarity, I listed up different variables from two "env_run.xml".

For I2000Clm51BgcCrop:
<entry id="CCSM_BGC" value="none">
<entry id="CCSM_CO2_PPMV" value="367.0">
<entry id="DATM_PRESAERO" value="clim_2000">
<entry id="DATM_PRESNDEP" value="clim_2000">
<entry id="DATM_CO2_TSERIES" value="none">
<entry id="CLM_NML_USE_CASE" value="2000_control">
<entry id="CLM_CO2_TYPE" value="constant">

For ISSP126Clm50BgcCrop:
<entry id="CCSM_BGC" value="CO2A">
<entry id="CCSM_CO2_PPMV" value="284.7">
<entry id="DATM_PRESAERO" value="SSP1-2.6">
<entry id="DATM_PRESNDEP" value="SSP1-2.6">
<entry id="DATM_CO2_TSERIES" value="SSP1-2.6">
<entry id="CLM_NML_USE_CASE" value="1850-2100_SSP1-2.6_transient">
<entry id="CLM_CO2_TYPE" value="diagnostic">

Therefore, I was working on running SSP126 using the 'I2000Clm51BgcCrop' compset (I did not use "anomaly forcing" option). For atmosphere driving (averaged values from 5 models), I used CLM1PT mode as input. For CO2, I revised relevant variables in the "env_run.xml" below:
<entry id="CCSM_BGC" value="CO2A">
<entry id="CCSM_CO2_PPMV" value="284.7">
<entry id="DATM_PRESAERO" value="SSP1-2.6">
<entry id="DATM_PRESNDEP" value="SSP1-2.6">
<entry id="DATM_CO2_TSERIES" value="SSP1-2.6">
<entry id="CLM_CO2_TYPE" value="diagnostic">

Although the simulation runs successfully, I was wondering whether this method does work. For your convenience, I attached "datm.streams.xml".

Thank you for your input in advance!

 

[slevis]

At first glance this seems fine. To convince yourself beyond doubt, you need to check the output from your simulation.