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formula to determine ice_cov from sst_cpl // QNEG4 warning and subsequent model crash

C

climatemodelling@gmx_com

Member
Dear Forum, What is the formula to calculate ice_cov from the sst_cpl variable? I am adding an SST trend to the original boundary condition file and would like to adjust the ice coverage variable to fit the new SSTs. I guess an SST value of -1.8 means ice_cov = 1. But what are the temperature bounds for the ice coverage range between 1 and 0? Thank you!
 
R

rneale

Rich Neale
CAM Project Scientist
Staff member
Check out the algorithim details in the Hurrell et al. (2008) paper.http://journals.ametsoc.org/doi/abs/10.1175/2008JCLI2292.1
 
R

rneale

Rich Neale
CAM Project Scientist
Staff member
Check out the algorithim details in the Hurrell et al. (2008) paper.http://journals.ametsoc.org/doi/abs/10.1175/2008JCLI2292.1
 
C

climatemodelling@gmx_com

Member
Thank you for the provided information! I checked the hurrell SST boundary condition file and the relationship between the variables SST_CPL and ICE_COV is not always exactly the value that I would exspect from the equation in the paper.I am running a F-compset and added an SST trend (~ 1degC / 10 years) to the original hurrell SST climatology. When running the model with the original non-modified ICE_COV climatology and the new SSTs the model crashes during first couple of timesteps. I already tried setting DIVDAMPN=2.0_r8, however the model still crashes after a couple of time steps with the following error message:  QNEG4 WARNING from TPHYSAC  Max possible LH flx exceeded at    5 points. , Worst excess =  -1.4439E-05, lchnk = 520, i =    4, same as indices lat =  56, lon =  96 QNEG4 WARNING from TPHYSAC  Max possible LH flx exceeded at    1 points. , Worst excess =  -3.3023E-06, lchnk = 487, i =   13, same as indices lat =  53, lon =  47 QNEG4 WARNING from TPHYSAC  Max possible LH flx exceeded at    1 points. , Worst excess =  -4.3819E-06, lchnk = 488, i =   13, same as indices lat =  53, lon =  48 *** Process received signal *** Signal: Segmentation fault (11)Signal code: Address not mapped (1)Failing at address: 0xffffffff2db8bc78 I am not 100% sure how to generate new ICE_COV values that comply with my new SSTs and don't cause the model to crash. Is there a namelist option to calculate the correct ice_cover from the given SSTs? Thank you very much in advance! 
 
C

climatemodelling@gmx_com

Member
Thank you for the provided information! I checked the hurrell SST boundary condition file and the relationship between the variables SST_CPL and ICE_COV is not always exactly the value that I would exspect from the equation in the paper.I am running a F-compset and added an SST trend (~ 1degC / 10 years) to the original hurrell SST climatology. When running the model with the original non-modified ICE_COV climatology and the new SSTs the model crashes during first couple of timesteps. I already tried setting DIVDAMPN=2.0_r8, however the model still crashes after a couple of time steps with the following error message:  QNEG4 WARNING from TPHYSAC  Max possible LH flx exceeded at    5 points. , Worst excess =  -1.4439E-05, lchnk = 520, i =    4, same as indices lat =  56, lon =  96 QNEG4 WARNING from TPHYSAC  Max possible LH flx exceeded at    1 points. , Worst excess =  -3.3023E-06, lchnk = 487, i =   13, same as indices lat =  53, lon =  47 QNEG4 WARNING from TPHYSAC  Max possible LH flx exceeded at    1 points. , Worst excess =  -4.3819E-06, lchnk = 488, i =   13, same as indices lat =  53, lon =  48 *** Process received signal *** Signal: Segmentation fault (11)Signal code: Address not mapped (1)Failing at address: 0xffffffff2db8bc78 I am not 100% sure how to generate new ICE_COV values that comply with my new SSTs and don't cause the model to crash. Is there a namelist option to calculate the correct ice_cover from the given SSTs? Thank you very much in advance! 
 
C

climatemodelling@gmx_com

Member
I guess I need to do one the following:(1) Find a way to calculate the correct ICE_COV from my modified SST_CPL. Is there a script available based on the hurrell paper?(2) Tell the model to ignore the prescribed ICE_COV values and calculate them instead. Is this possible within the F compsets (via namelist options)? Thanks Edit: The warnings and subsequent model crash occur during the very first time step of the model run. 
 
C

climatemodelling@gmx_com

Member
I guess I need to do one the following:(1) Find a way to calculate the correct ICE_COV from my modified SST_CPL. Is there a script available based on the hurrell paper?(2) Tell the model to ignore the prescribed ICE_COV values and calculate them instead. Is this possible within the F compsets (via namelist options)? Thanks Edit: The warnings and subsequent model crash occur during the very first time step of the model run. 
 
hannay

hannay

Cecile Hannay
AMWG Liaison
Staff member
(1) There is no script to calculate the ICE_COV from a modified SST_CPL but it should be easy to implement.
(2) The F compset uses a thermodynamic sea-ice with a prescribed sea-ice coverage with a 2-meter depth in NH (and 1-meter in SH).
 
hannay

hannay

Cecile Hannay
AMWG Liaison
Staff member
(1) There is no script to calculate the ICE_COV from a modified SST_CPL but it should be easy to implement.
(2) The F compset uses a thermodynamic sea-ice with a prescribed sea-ice coverage with a 2-meter depth in NH (and 1-meter in SH).
 
C

climatemodelling@gmx_com

Member
thank you hannay for the clarification.regarding the skin temperature boundary condition file: I assume only the prescribed values over the ocean are used and skin temperatures over land are computed by the land model?
 
C

climatemodelling@gmx_com

Member
thank you hannay for the clarification.regarding the skin temperature boundary condition file: I assume only the prescribed values over the ocean are used and skin temperatures over land are computed by the land model?
 
hannay

hannay

Cecile Hannay
AMWG Liaison
Staff member
This is correct. The surface temperatures are prescribed over ocean but not over land.
 
hannay

hannay

Cecile Hannay
AMWG Liaison
Staff member
This is correct. The surface temperatures are prescribed over ocean but not over land.
 
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