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

How to set the orbital parameter acceleration in CESM1.0?

X

xiaohardy@163_com

Member
Hi, everyone,we  want to proceed some transient simulations about the climate change during the Holocene (~10Ka B.P.)  based on CESM1.0. In this experiment, we only want to change the orbital parameters as the main forcing across the whole Holocene. Considering the computing consumes, we have to have  the orbital parameters with an acceleration of factor 10/100 integrated. But we do not know how to modify the CESM1.0 to simulate with the forcing of the orbital parameters acceleration of 10/100. we have found some papers addressed this issue based on the CCSM3. But we don't know how to accelerate the orbital parameters with a factor of 10 or 100 in CESM1.0 in detail. Could you give us some suggestions about the orbital parameters acceleration?  it would be appreciated. Looking forward to your reply.   Xiao
 
S

shields

New Member
orbital parameters are based on berger 1978.  below is doc snippet found in code (in csm_share directories).  i believe this is the same code that is used in ccsm3.  orbital params are computed for a specific time slice relative to 1950, or by explicitly setting eccentricity, obliquity, and precession.   i'm not sure what you mean by acceleration. if you want to change the way they are computed, you will have to modify the code.   here is what the code allows via the namelist for the coupler  (search for "setting orbital parameters")http://www.cesm.ucar.edu/models/paleo/faq from code shr_orb_mod.F90:! Calculate earths orbital parameters using Dave Threshers formula which came from Berger, Andre.  1978  "A Simple Algorithm to Compute Long-Term Variations of Daily Insolation".  Contribution 18, Institute of Astronomy  and Geophysics, Universite Catholique de Louvain, Louvain-la-Neuve, Belgium 
 
S

shields

New Member
orbital parameters are based on berger 1978.  below is doc snippet found in code (in csm_share directories).  i believe this is the same code that is used in ccsm3.  orbital params are computed for a specific time slice relative to 1950, or by explicitly setting eccentricity, obliquity, and precession.   i'm not sure what you mean by acceleration. if you want to change the way they are computed, you will have to modify the code.   here is what the code allows via the namelist for the coupler  (search for "setting orbital parameters")http://www.cesm.ucar.edu/models/paleo/faq from code shr_orb_mod.F90:! Calculate earths orbital parameters using Dave Threshers formula which came from Berger, Andre.  1978  "A Simple Algorithm to Compute Long-Term Variations of Daily Insolation".  Contribution 18, Institute of Astronomy  and Geophysics, Universite Catholique de Louvain, Louvain-la-Neuve, Belgium 
 
S

shields

New Member
orbital parameters are based on berger 1978.  below is doc snippet found in code (in csm_share directories).  i believe this is the same code that is used in ccsm3.  orbital params are computed for a specific time slice relative to 1950, or by explicitly setting eccentricity, obliquity, and precession.   i'm not sure what you mean by acceleration. if you want to change the way they are computed, you will have to modify the code.   here is what the code allows via the namelist for the coupler  (search for "setting orbital parameters")http://www.cesm.ucar.edu/models/paleo/faq from code shr_orb_mod.F90:! Calculate earths orbital parameters using Dave Threshers formula which came from Berger, Andre.  1978  "A Simple Algorithm to Compute Long-Term Variations of Daily Insolation".  Contribution 18, Institute of Astronomy  and Geophysics, Universite Catholique de Louvain, Louvain-la-Neuve, Belgium 
 
S

shields

New Member
orbital parameters are based on berger 1978.  below is doc snippet found in code (in csm_share directories).  i believe this is the same code that is used in ccsm3.  orbital params are computed for a specific time slice relative to 1950, or by explicitly setting eccentricity, obliquity, and precession.   i'm not sure what you mean by acceleration. if you want to change the way they are computed, you will have to modify the code.   here is what the code allows via the namelist for the coupler  (search for "setting orbital parameters")http://www.cesm.ucar.edu/models/paleo/faq from code shr_orb_mod.F90:! Calculate earths orbital parameters using Dave Threshers formula which came from Berger, Andre.  1978  "A Simple Algorithm to Compute Long-Term Variations of Daily Insolation".  Contribution 18, Institute of Astronomy  and Geophysics, Universite Catholique de Louvain, Louvain-la-Neuve, Belgium 
 
X

xiaohardy@163_com

Member
Hi, ShieldsThanks very much. That is very helpful.I have read the code of the shr_orb_mod.F90. But I still confused the namelist of orb_iyear_align, [/b]i do not quite understand the instruction. How is the orb_iyear_align [/b]working?Thanks again.  Xiao   
 
X

xiaohardy@163_com

Member
Hi, ShieldsThanks very much. That is very helpful.I have read the code of the shr_orb_mod.F90. But I still confused the namelist of orb_iyear_align, [/b]i do not quite understand the instruction. How is the orb_iyear_align [/b]working?Thanks again.  Xiao   
 
X

xiaohardy@163_com

Member
Hi, ShieldsThanks very much. That is very helpful.I have read the code of the shr_orb_mod.F90. But I still confused the namelist of orb_iyear_align, [/b]i do not quite understand the instruction. How is the orb_iyear_align [/b]working?Thanks again.  Xiao   
 
X

xiaohardy@163_com

Member
Hi, ShieldsThanks very much. That is very helpful.I have read the code of the shr_orb_mod.F90. But I still confused the namelist of orb_iyear_align, [/b]i do not quite understand the instruction. How is the orb_iyear_align [/b]working?Thanks again.  Xiao   
 
X

xiaohardy@163_com

Member
I also have another question. We want to accelerated the orbtial change.For example, we wanna simulate the climate change of the past 2000 years which is only forced by orbital parameters based on the CESM1.0. The acceleration for the forced orbital parameters means that the simulation begins at value of the 1st year of orbital parameters, then the next model year, the orbital parameters change to the value of 101st year, and the third model year, which is forced by the value of 201st year of orbatial paramters, and so on. Does it have to modify the code shr_orb_mod.F90 to realize the acceleration? Thanks in advanced.
 
X

xiaohardy@163_com

Member
I also have another question. We want to accelerated the orbtial change.For example, we wanna simulate the climate change of the past 2000 years which is only forced by orbital parameters based on the CESM1.0. The acceleration for the forced orbital parameters means that the simulation begins at value of the 1st year of orbital parameters, then the next model year, the orbital parameters change to the value of 101st year, and the third model year, which is forced by the value of 201st year of orbatial paramters, and so on. Does it have to modify the code shr_orb_mod.F90 to realize the acceleration? Thanks in advanced.
 
X

xiaohardy@163_com

Member
I also have another question. We want to accelerated the orbtial change.For example, we wanna simulate the climate change of the past 2000 years which is only forced by orbital parameters based on the CESM1.0. The acceleration for the forced orbital parameters means that the simulation begins at value of the 1st year of orbital parameters, then the next model year, the orbital parameters change to the value of 101st year, and the third model year, which is forced by the value of 201st year of orbatial paramters, and so on. Does it have to modify the code shr_orb_mod.F90 to realize the acceleration? Thanks in advanced.
 
X

xiaohardy@163_com

Member
I also have another question. We want to accelerated the orbtial change.For example, we wanna simulate the climate change of the past 2000 years which is only forced by orbital parameters based on the CESM1.0. The acceleration for the forced orbital parameters means that the simulation begins at value of the 1st year of orbital parameters, then the next model year, the orbital parameters change to the value of 101st year, and the third model year, which is forced by the value of 201st year of orbatial paramters, and so on. Does it have to modify the code shr_orb_mod.F90 to realize the acceleration? Thanks in advanced.
 
S

shields

New Member
all your questions are answered in the documentation: http://www.cesm.ucar.edu/models/cesm1.2/cesm/doc/modelnl/nl_drv.html note that you should only modify the code if you want to do something that is not already built in to the coupler.  based on your explanation, you may want to explore the "variable_year" option of orb_mode... which may satisfy your needs w/o modifying code.   good luck!
 
S

shields

New Member
all your questions are answered in the documentation: http://www.cesm.ucar.edu/models/cesm1.2/cesm/doc/modelnl/nl_drv.html note that you should only modify the code if you want to do something that is not already built in to the coupler.  based on your explanation, you may want to explore the "variable_year" option of orb_mode... which may satisfy your needs w/o modifying code.   good luck!
 
S

shields

New Member
all your questions are answered in the documentation: http://www.cesm.ucar.edu/models/cesm1.2/cesm/doc/modelnl/nl_drv.html note that you should only modify the code if you want to do something that is not already built in to the coupler.  based on your explanation, you may want to explore the "variable_year" option of orb_mode... which may satisfy your needs w/o modifying code.   good luck!
 
You must log in or register to reply here.
Top