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Anomaly forcing climate only and CO2 only

MikeYuan

tfYuan
Member
Normally, that compset creates a model run 2015-2100 and the CO2 is setup to be transient for 2015-2100 also.
So, you could run that and stop at 2060 if you are just interested in 2050-2060 results.
Is that what you want to do?
However, the computational cost is large for me. So I want use the CO2 of 2050 for beginning, is there any other way to achieve this?(replacing 2015 with 2050)
 

MikeYuan

tfYuan
Member
Not really. You really need an initial file for 2050 to do a 2050-2060 run that has 2050-2060 CO2 and 2050-2060 landcover.
You could analyze some existing CESM2 SSP585 simulations:

Dear Mr.Oleson, Thanks for your patient explanation.
But when I tried to write the ' streams="datm.streams.txt.co2tseries.SSP5-8.5 2015 2050 2100" ' in the file of user_nl_datm, the CO2 in 2050 that seems to work.
Besides, you mentioned that I need to spin up separately in 2015 if I want to get the initial file of 2050. Therefore, I just spin-up for 35years from 2015 then I will get the initail file of 2050?
Looking forward to your reply

Thank you very much
Mike
 

oleson

Keith Oleson
CSEG and Liaisons
Staff member
For a model run for 2015-2049 (35 years) that will give you CO2 for 2050-2084 and landcover, nitrogen deposition, etc. for 2015-2049.
 

MikeYuan

tfYuan
Member
For a model run for 2015-2049 (35 years) that will give you CO2 for 2050-2084 and landcover, nitrogen deposition, etc. for 2015-2049.
Dear Mr.Oleson, Thanks for your patient explanation.
I am using I1850Clm50BgcCrop, if I want to use the humidity variable--"QBOT" the same as the "QBOT" of I2000Clm50BgcCrop, how should I do it?
Looking forward to your reply

Thank you very much
Mike
 

ohmpawat

ohmpawat chen
Member
DATM_CLMNCEP_YR_ALIGN is the model simulation year to align the stream to. It is independent of the RUN_STARTDATE.
The example of the I850 case you reference is:

RUN_STARTDATE=0001-01-01 This means that the model will start at year "1"

DATM_CLMNCEP_YR_ALIGN=1
DATM_CLMNCEP_YR_START=1901
DATM_CLMNCEP_YR_END=1920

This means that model simulation year 1 will align with the first year of atmospheric forcing specified (1901).
The last year of atmospheric forcing is 1920.
So, if the datm is setup to cycle through the forcing years, as it is by default in this case:

Simulation Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 ....
DATM Forcing Year 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1901 .....

Another more complicated case is a historical case. We want to run 1850-2014 but we only have atmospheric forcing for 1901-2014. So we like to start by looping over 1901-1920 forcing for the 1850-1900 period. So we use these settings:

RUN_STARTDATE=1850-01-01

DATM_CLMNCEP_YR_ALIGN=1901
DATM_CLMNCEP_YR_START=1901
DATM_CLMNCEP_YR_END=1920

This will look like:

Simulation Year 1850 1851 ... 1860 ... 1861 ... 1880 ... 1881 ... 1900 ... 1901
DATM Forcing year 1910 1911 ... 1920 ... 1901 ... 1920 ... 1901 ... 1920 ... 1901

It's not immediately obvious from the settings but note that simulation year 1850 will start with 1910 forcing in order to end up with simulation year 1901 being forced with 1901 atm as specified.

My advice would be to do some short runs with various settings and see how the simulation years interact with the forcing years by looking at the atm log.
Hello, if my RUN_STARTDATE=1996-01-01,and my YR_ALIGN=1850, YR_START=1850,YR_END=2016, STOP_N=10,STOP_OPTION=nyear. I need to run 10 years. What year of forcing data will I use?
 

oleson

Keith Oleson
CSEG and Liaisons
Staff member
First of all, this will only work if you have atm forcing data through 2016. Our default forcing data, GSWP3V1, only goes through the end of 2014. Are you using your own forcing data?
 

ohmpawat

ohmpawat chen
Member
This would also only work if you had forcing data for 1850-2016.
I’m confused about the relationship between ALIGN, YR_START and RUN_STARTDATE. If my RUN_STARTDATE=1996-01-01,and my YR_ALIGN=1850, YR_START=1850,YR_END=2016, STOP_N=10,STOP_OPTION=nyear. I need to run 10 years. What year of forcing data will I use? My data is from 1950 to 2101.
 

oleson

Keith Oleson
CSEG and Liaisons
Staff member
Simplest thing to do is DATM_CLMNCEP_YR_START=1996, DATM_CLMNCEP_YR_END=2016, DATM_CLMNCEP_YR_ALIGN=1996, RUN_STARTDATE=1996-01-01.
The model will start in year 1996 and should use year 1996 of the forcing data. If you run 11 years, the model will run 1996-2016 and use 1996-2016 forcing data.
Is that what you want to do?
 

ohmpawat

ohmpawat chen
Member
Simplest thing to do is DATM_CLMNCEP_YR_START=1996, DATM_CLMNCEP_YR_END=2016, DATM_CLMNCEP_YR_ALIGN=1996, RUN_STARTDATE=1996-01-01.
The model will start in year 1996 and should use year 1996 of the forcing data. If you run 11 years, the model will run 1996-2016 and use 1996-2016 forcing data.
Is that what you want to do?
Yes. But I have done my simulation and found YR_ALIGN and YR_START foget to change to correspond to my own forcing data. So I don't know whether the setting still use the right year of forcing data.
 

oleson

Keith Oleson
CSEG and Liaisons
Staff member
You'll need to look at your atm log to see what forcing data was used.
 

ohmpawat

ohmpawat chen
Member
You'll need to look at your atm log to see what forcing data was used.
OK, I will check it. Besides, I just change YR_ALIGN=1996,YR_START=1996,RUN_STARTDATE=1996-01-01, and run. There is an error "ERROR: dt limit2 19960116 43200 19960215". I don't know what is wrong.
 
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