Scheduled Downtime
On Tuesday 24 October 2023 @ 5pm MT the forums will be in read only mode in preparation for the downtime. On Wednesday 25 October 2023 @ 5am MT, this website will be down for maintenance and expected to return online later in the morning.
Normal Operations
The forums are back online with normal operations. If you notice any issues or errors related to the forums, please reach out to help@ucar.edu

Change CO2 or LAI in IHIST experiment

H

Houhhu

Nash
Member
Hi all,
I am looking forward to conducting some experiments with constant CO2 or constant LAI in the future projection.
I checked the env_run.xml and find these options:

<entry id="CCSM_CO2_PPMV" value="367.0">
<type>real</type>
<valid values/>
<desc>

<entry id="DATM_CO2_TSERIES" value="20tr">
<type>char</type>
<valid_values>none,20tr,20tr.latbnd,rcp2.6,rcp4.5,rcp6.0,rcp8.5</valid_values>
<desc>DATM CO2 time series</desc>
</entry>

But I didn't find any options for setting LAI constant.If I want to set up an experiment in which CO2 and LAI do not change in future simulations, how should I configure it?
 
H

Houhhu

Nash
Member
Based on some previous answers, I realize that LAI files can be specified in the SP compset, and modify the settings in lnd_in.
Like:

&lai_streams
lai_mapalgo = 'bilinear'
model_year_align_lai = 2001
stream_fldfilename_lai = '/glade/p/cesmdata/cseg/inputdata/lnd/clm2/lai_streams/MODISPFTLAI_0.5x0.5_c140711.nc'
stream_year_first_lai = 2001
stream_year_last_lai = 2013
/
But in BGC-Crop compset, I check the lnd_in file and didn't find the setting about lai_streams.

So I would like to ask how to keep CO2 concentration and LAI constant during model runs If i investigate the impact of CO2 and LAI on future climate in ISSP126Clm50BgcCrop.(is it possible to set "CCSM_CO2_PPMV" as constant value and use the file '/glade/p/cesmdata/cseg/inputdata/lnd/clm2/lai_streams/MODISPFTLAI_0.5x0.5_c140711.nc' one of montly average LAI value as the input?)

Any help will be deeply appreciated!
 
slevis

slevis

Moderator
As you said, setting the CO2 is easy. But you want the lai constant, and you also want a BGC-crop compset, because you want active carbon and nitrogen cycles, right? I think you're correct that you need to modify the code to read the lai file that you want.
 
H

Houhhu

Nash
Member
slevis said:
As you said, setting the CO2 is easy. But you want the lai constant, and you also want a BGC-crop compset, because you want active carbon and nitrogen cycles, right? I think you're correct that you need to modify the code to read the lai file that you want.
Click to expand...
Thanks for your reply, slevis! But I still have some questions.
Q1:In BGC-Crop compset, LAI is prognostic in this configuration. Do we still need LAI file as input data? Can I prescribe LAI in this compset?
Q2:In Sp compset, The LAI data in the file '/glade/p/cesmdata/cseg/inputdata/lnd/clm2/lai_streams/MODISPFTLAI_0.5x0.5_c140711.nc' spans from 2001 to 2013, and it appears to be independent of the running year of the model. If the compset runs from 1980 to 2000, Is the input LAI data still from 2001 to 2013?
Is it possible to configure the model to read the desired LAI file for each year during its runtime?

Looking forward to your reply!
 
O

oleson

Keith Oleson
CSEG and Liaisons
Staff member
Q1: Right, LAI is prognostic in the BGC-Crop compset. So you don't need the LAI as input data and you cannot prescribe LAI in that compset currently.
Q2: The available input LAI dataset is 2001 to 2013. How the reading of that data lines up with the model years will depend on the setting of model_year_align_lai. For example, if you run the model for 2001 to 2013 and model_year_align_lai is set to 2001, the model will use year 2001 LAI for model year 2001, year 2002 LAI for model year 2002, etc.
 
H

Houhhu

Nash
Member
oleson said:
Q1: Right, LAI is prognostic in the BGC-Crop compset. So you don't need the LAI as input data and you cannot prescribe LAI in that compset currently.
Q2: The available input LAI dataset is 2001 to 2013. How the reading of that data lines up with the model years will depend on the setting of model_year_align_lai. For example, if you run the model for 2001 to 2013 and model_year_align_lai is set to 2001, the model will use year 2001 LAI for model year 2001, year 2002 LAI for model year 2002, etc.
Click to expand...
Thanks for this answer, Oleson! If the model year is not within 2001 to 2013, the model will use surface dataset LAI right?
 
O

oleson

Keith Oleson
CSEG and Liaisons
Staff member
No, the model will only use the surface dataset LAI if use_lai_streams=.false. For model years outside of 2001 to 2013, the LAI from the streams file will be used. The year used will depend on the settings above. For example, for the settings above, if the model year is 2014, then LAI for year 2001 from the streams file will be used because taxmode is set to cycle by default for this stream, which means that the data will be cycled (repeated).
 
H

Houhhu

Nash
Member
oleson said:
No, the model will only use the surface dataset LAI if use_lai_streams=.false. For model years outside of 2001 to 2013, the LAI from the streams file will be used. The year used will depend on the settings above. For example, for the settings above, if the model year is 2014, then LAI for year 2001 from the streams file will be used because taxmode is set to cycle by default for this stream, which means that the data will be cycled (repeated).
Click to expand...
Thank you very much!
 
H

Houhhu

Nash
Member
oleson said:
No, the model will only use the surface dataset LAI if use_lai_streams=.false. For model years outside of 2001 to 2013, the LAI from the streams file will be used. The year used will depend on the settings above. For example, for the settings above, if the model year is 2014, then LAI for year 2001 from the streams file will be used because taxmode is set to cycle by default for this stream, which means that the data will be cycled (repeated).
Click to expand...
Sorry for bother you, some questions still confuse me. My plan is to conduct some experiments: one is to run the model with SSP compset. Based on the first experiment, keep CO2 constant and monthly LAI climatology constant(like MDOIS LAI averaged from 2001 to 2013) respectively.
Q1: I would like to konw in SP compset, carbon and nitrogen cycles is still active?
Q2: I checked the lnd_in file,but I didnt find the setting of taxmode. Only found the taxmode in datm_in.
Q3: Is it reasonable for the BGC-Crop compset to keep LAI constant during model running, because I have already known that LAI is changing with model years. Or should I use the SP compset?

Looking forward to you reply!Thanks
 
O

oleson

Keith Oleson
CSEG and Liaisons
Staff member
1) No
2) The taxmode for the lai streams file is set internally in the code (src/biogeochem/SatellitePhenologyMod.F90):

call shr_strdata_create(sdat_lai,name="laidyn", &
pio_subsystem=pio_subsystem, &
pio_iotype=shr_pio_getiotype(inst_name), &
mpicom=mpicom, compid=comp_id, &
gsmap=gsmap_lnd_gdc2glo, ggrid=dom_clm, &
nxg=ldomain%ni, nyg=ldomain%nj, &
yearFirst=stream_year_first_lai, &
yearLast=stream_year_last_lai, &
yearAlign=model_year_align_lai, &
offset=0, &
domFilePath='', &
domFileName=trim(stream_fldFileName_lai), &
domTvarName='time', &
domXvarName='lon' , &
domYvarName='lat' , &
domAreaName='area', &
domMaskName='mask', &
filePath='', &
filename=(/stream_fldFileName_lai/), &
fldListFile=fldList, &
fldListModel=fldList, &
fillalgo='none', &
mapalgo=lai_mapalgo, &
tintalgo=lai_tintalgo, &
calendar=get_calendar(), &
taxmode='cycle' )

3) As we noted previously, LAI is prognostic in the BGC compset and there isn't currently any capability to prescribe it as constant.
 
You must log in or register to reply here.
Top