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Vegetation problem in CTSM run

maruf2812

Montasir Maruf
Member
We have run a case (2000_DATM%NLDAS2_CLM50%NWP-BGC-CROP_SICE_SOCN_MOSART_SGLC_SWAV_SIAC_SESP --res nldas2_rnldas2_mnldas2) in CTSM. While checking GPP results we found that there is no vegetation in South west part of USA all the year round, not even in summer but the other regions get vegetation in summer. I have attached two images, first one is in month of June and second one is in month of January.

1.JPG

2.JPG
 

oleson

Keith Oleson
CSEG and Liaisons
Staff member
The default initialization file (finidat in lnd_in) for this configuration is a 2deg file that has several "dead" gridcells in that region. Those 2deg gridcells are imprinting on your NLDAS grid.
The best way forward is to spinup the model according to these instructions:


Best results for your configuration would likely involve a "cold start" in accelerated decomposition (AD) mode and then a normal spinup following that.
 

maruf2812

Montasir Maruf
Member
@oleson thank you very much for the reply. In the instruction they suggest this case for spinup (./create_newcase -case BGC_spinup -res f19_g17_gl4 -compset I1850Clm50BgcCropCru). Do we need to change it according to our own case?
 

oleson

Keith Oleson
CSEG and Liaisons
Staff member
Yes, you should spinup using your own case/resolution/forcing data.
 

maruf2812

Montasir Maruf
Member
@oleson thank you for the support. For the spinup run can I use my last run output as initial file (initialization) or I have to start from the scratch (cold start)?
 

oleson

Keith Oleson
CSEG and Liaisons
Staff member
If you use your last run output as initialization then also set the following in your user_nl_clm for your "AD" spinup run:

reseed_dead_plants = .true.

This will "reseed" dead plants with a bit of carbon/nitrogen to give them a chance to grow again in the NLDAS climate.
 

maruf2812

Montasir Maruf
Member
Hi @oleson I have completed the spinup in AD mode for 270 years but some part of western USA still shows zero vegetation. In this case should I start the normal spinup mode? Does it improve in normal spinup mode? Thank you.
 

oleson

Keith Oleson
CSEG and Liaisons
Staff member
Once the vegetation is dead it won't come back in normal spinup mode. CLM does have some problem growing vegetation in parts of the western U.S.
 

oleson

Keith Oleson
CSEG and Liaisons
Staff member
It's a bit of a research issue that, to my knowledge, has not been explored It seems to vary in severity as a function of atmospheric forcing, among other things. If it's important to your research you could try different atmospheric forcing (e.g., GSWP3). I've attached results for TLAI from a recent global CTSM5.1 simulation that indicates that while TLAI is quite low in this region, it's not completely dead.
You could also run in satellite phenology (SP) mode in which TLAI is prescribed from satellite data.

plot_TLAI.png
 

oleson

Keith Oleson
CSEG and Liaisons
Staff member
You could change the compset you are running:

2000_DATM%NLDAS2_CLM50%NWP-BGC-CROP_SICE_SOCN_MOSART_SGLC_SWAV_SIAC_SESP

to:

2000_DATM%NLDAS2_CLM50%NWP-SP_SICE_SOCN_MOSART_SGLC_SWAV_SIAC_SESP

Replace BGC-CROP with SP
 
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