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Which variables to include in ocean surface salt budget?

J

j08lue@gmail_com

New Member
Dear colleagues,I want to compute an ocean surface salt budget for a G-case CESM1.2 run. Which variables from the POP output do I need to include?I am quite confident about SFWF (Virtual Salt Flux in FW Flux formulation) and SFWF_WRST (Virtual Salt Flux due to weak restoring).But do I also need to add SALT_F (Salt Flux from Coupler), which is seems to contain salt fluxes due to sea ice formation/melting, or is this included in SFWF?Finally, are all these surface salt fluxes positive upward, i.e. do positive values mean salt is removed from the ocean?Thanks for any help and best regards,Jonas
 
J

j08lue@gmail_com

New Member
Sorry for not posting this earlier - I received an answer to my question from S. Yeager (NCAR) in 2014. I hope it is okay if I reproduce it here: >>>The net surface forcing of POP model salinity isSFWF - QFLUX/latent_heat_fusion/1.e4            [kg FW /m^2/s]where bold-faced indicates variables found in POP model output netcdf, latent heat of fusion can also be found there, and the 1.e4 factor is needed for correct units. The QFLUX term isn't included in SFWFbecause it's not considered a flux exchanged between model components -- it is the FW flux associated with frazil ice formation which occurs within the ocean model! This net surface flux can be broken into components as follows:SFWF - QFLUX/latent_heat_fusion/1.e4   =      PREC_F + EVAP_F + ROFF_F + IOFF_F + MELT_F    + SALT_F*(sflux_factor/salinity_factor)    - QFLUX/latent_heat_fusion/1.e4    + (any weak or strong salinity restoring) MELT_F represents any FW flux computed by the ice model and sent to the ocean (associated with ice melt/growth), while SALT_F represents any SALT flux computed by the ice model and sent to the ocean (associated with the fact that ice melt/growth requires that salt be added/removed from the ocean because ice has a constant salinity of ~4 psu!). This salt flux must of course be converted to appropriate units; in the above equation, it is converted from (kg SALT/m^2/s) to (kg FW/m^2/s).  Note that we don't generally save salinity restoring fluxes, so any difference between the RHS and LHS of the above equation computed from POP output fields might be attributable to salinity restoring.SFWF - (PREC_F + EVAP+F + ROFF_F + IOFF_F + MELT_F) - SALT_F*(sflux_factor/salinity_factor)= (any weak or strong salinity restoring) The equation above can be compared to the POP code in forcing_coupled.F90; specifically the line        STF(:,:,2,iblock) = RCALCT(:,:,iblock)*(  &            (PREC_F(:,:,iblock) + EVAP_F(:,:,iblock) +  &                MELT_F(:,:,iblock) + ROFF_F(:,:,iblock) + IOFF_F(:,:,iblock))*salinity_factor &            + SALT_F(:,:,iblock)*sflux_factor)For guidance on conversion of FW flux to virtual salt flux, etc, refer to POP_ConstantsMod.F90
 
J

j08lue@gmail_com

New Member
Sorry for not posting this earlier - I received an answer to my question from S. Yeager (NCAR) in 2014. I hope it is okay if I reproduce it here: >>>The net surface forcing of POP model salinity isSFWF - QFLUX/latent_heat_fusion/1.e4            [kg FW /m^2/s]where bold-faced indicates variables found in POP model output netcdf, latent heat of fusion can also be found there, and the 1.e4 factor is needed for correct units. The QFLUX term isn't included in SFWFbecause it's not considered a flux exchanged between model components -- it is the FW flux associated with frazil ice formation which occurs within the ocean model! This net surface flux can be broken into components as follows:SFWF - QFLUX/latent_heat_fusion/1.e4   =      PREC_F + EVAP_F + ROFF_F + IOFF_F + MELT_F    + SALT_F*(sflux_factor/salinity_factor)    - QFLUX/latent_heat_fusion/1.e4    + (any weak or strong salinity restoring) MELT_F represents any FW flux computed by the ice model and sent to the ocean (associated with ice melt/growth), while SALT_F represents any SALT flux computed by the ice model and sent to the ocean (associated with the fact that ice melt/growth requires that salt be added/removed from the ocean because ice has a constant salinity of ~4 psu!). This salt flux must of course be converted to appropriate units; in the above equation, it is converted from (kg SALT/m^2/s) to (kg FW/m^2/s).  Note that we don't generally save salinity restoring fluxes, so any difference between the RHS and LHS of the above equation computed from POP output fields might be attributable to salinity restoring.SFWF - (PREC_F + EVAP+F + ROFF_F + IOFF_F + MELT_F) - SALT_F*(sflux_factor/salinity_factor)= (any weak or strong salinity restoring) The equation above can be compared to the POP code in forcing_coupled.F90; specifically the line        STF(:,:,2,iblock) = RCALCT(:,:,iblock)*(  &            (PREC_F(:,:,iblock) + EVAP_F(:,:,iblock) +  &                MELT_F(:,:,iblock) + ROFF_F(:,:,iblock) + IOFF_F(:,:,iblock))*salinity_factor &            + SALT_F(:,:,iblock)*sflux_factor)For guidance on conversion of FW flux to virtual salt flux, etc, refer to POP_ConstantsMod.F90
 
J

j08lue@gmail_com

New Member
Sorry for not posting this earlier - I received an answer to my question from S. Yeager (NCAR) in 2014. I hope it is okay if I reproduce it here: >>>The net surface forcing of POP model salinity isSFWF - QFLUX/latent_heat_fusion/1.e4            [kg FW /m^2/s]where bold-faced indicates variables found in POP model output netcdf, latent heat of fusion can also be found there, and the 1.e4 factor is needed for correct units. The QFLUX term isn't included in SFWFbecause it's not considered a flux exchanged between model components -- it is the FW flux associated with frazil ice formation which occurs within the ocean model! This net surface flux can be broken into components as follows:SFWF - QFLUX/latent_heat_fusion/1.e4   =      PREC_F + EVAP_F + ROFF_F + IOFF_F + MELT_F    + SALT_F*(sflux_factor/salinity_factor)    - QFLUX/latent_heat_fusion/1.e4    + (any weak or strong salinity restoring) MELT_F represents any FW flux computed by the ice model and sent to the ocean (associated with ice melt/growth), while SALT_F represents any SALT flux computed by the ice model and sent to the ocean (associated with the fact that ice melt/growth requires that salt be added/removed from the ocean because ice has a constant salinity of ~4 psu!). This salt flux must of course be converted to appropriate units; in the above equation, it is converted from (kg SALT/m^2/s) to (kg FW/m^2/s).  Note that we don't generally save salinity restoring fluxes, so any difference between the RHS and LHS of the above equation computed from POP output fields might be attributable to salinity restoring.SFWF - (PREC_F + EVAP+F + ROFF_F + IOFF_F + MELT_F) - SALT_F*(sflux_factor/salinity_factor)= (any weak or strong salinity restoring) The equation above can be compared to the POP code in forcing_coupled.F90; specifically the line        STF(:,:,2,iblock) = RCALCT(:,:,iblock)*(  &            (PREC_F(:,:,iblock) + EVAP_F(:,:,iblock) +  &                MELT_F(:,:,iblock) + ROFF_F(:,:,iblock) + IOFF_F(:,:,iblock))*salinity_factor &            + SALT_F(:,:,iblock)*sflux_factor)For guidance on conversion of FW flux to virtual salt flux, etc, refer to POP_ConstantsMod.F90
 
J

j08lue@gmail_com

New Member
Sorry for not posting this earlier - I received an answer to my question from S. Yeager (NCAR) in 2014. I hope it is okay if I reproduce it here: >>>The net surface forcing of POP model salinity isSFWF - QFLUX/latent_heat_fusion/1.e4            [kg FW /m^2/s]where bold-faced indicates variables found in POP model output netcdf, latent heat of fusion can also be found there, and the 1.e4 factor is needed for correct units. The QFLUX term isn't included in SFWFbecause it's not considered a flux exchanged between model components -- it is the FW flux associated with frazil ice formation which occurs within the ocean model! This net surface flux can be broken into components as follows:SFWF - QFLUX/latent_heat_fusion/1.e4   =      PREC_F + EVAP_F + ROFF_F + IOFF_F + MELT_F    + SALT_F*(sflux_factor/salinity_factor)    - QFLUX/latent_heat_fusion/1.e4    + (any weak or strong salinity restoring) MELT_F represents any FW flux computed by the ice model and sent to the ocean (associated with ice melt/growth), while SALT_F represents any SALT flux computed by the ice model and sent to the ocean (associated with the fact that ice melt/growth requires that salt be added/removed from the ocean because ice has a constant salinity of ~4 psu!). This salt flux must of course be converted to appropriate units; in the above equation, it is converted from (kg SALT/m^2/s) to (kg FW/m^2/s).  Note that we don't generally save salinity restoring fluxes, so any difference between the RHS and LHS of the above equation computed from POP output fields might be attributable to salinity restoring.SFWF - (PREC_F + EVAP+F + ROFF_F + IOFF_F + MELT_F) - SALT_F*(sflux_factor/salinity_factor)= (any weak or strong salinity restoring) The equation above can be compared to the POP code in forcing_coupled.F90; specifically the line        STF(:,:,2,iblock) = RCALCT(:,:,iblock)*(  &            (PREC_F(:,:,iblock) + EVAP_F(:,:,iblock) +  &                MELT_F(:,:,iblock) + ROFF_F(:,:,iblock) + IOFF_F(:,:,iblock))*salinity_factor &            + SALT_F(:,:,iblock)*sflux_factor)For guidance on conversion of FW flux to virtual salt flux, etc, refer to POP_ConstantsMod.F90
 
G

g_vettoretti@utoronto_ca

New Member
Also of note is SNOW_F (snow flux) that is saved in the model. It is inherently included in the PREC_F variable and thus the calculation of SFWF. It is also used in the calculation of the total heat flux from the coupler (SHF) in the code.PREC_F:  Precipitation Flux from Cpl (rain+snow)
Thanks for the note Jonas. 
 
G

g_vettoretti@utoronto_ca

New Member
Also of note is SNOW_F (snow flux) that is saved in the model. It is inherently included in the PREC_F variable and thus the calculation of SFWF. It is also used in the calculation of the total heat flux from the coupler (SHF) in the code.PREC_F:  Precipitation Flux from Cpl (rain+snow)
Thanks for the note Jonas. 
 
G

g_vettoretti@utoronto_ca

New Member
Also of note is SNOW_F (snow flux) that is saved in the model. It is inherently included in the PREC_F variable and thus the calculation of SFWF. It is also used in the calculation of the total heat flux from the coupler (SHF) in the code.PREC_F:  Precipitation Flux from Cpl (rain+snow)
Thanks for the note Jonas. 
 
G

g_vettoretti@utoronto_ca

New Member
Also of note is SNOW_F (snow flux) that is saved in the model. It is inherently included in the PREC_F variable and thus the calculation of SFWF. It is also used in the calculation of the total heat flux from the coupler (SHF) in the code.PREC_F:  Precipitation Flux from Cpl (rain+snow)
Thanks for the note Jonas. 
 
U

ucas_qs

qiushi Zhang
Member
g_vettoretti@utoronto_ca said:
Also of note is SNOW_F (snow flux) that is saved in the model. It is inherently included in the PREC_F variable and thus the calculation of SFWF. It is also used in the calculation of the total heat flux from the coupler (SHF) in the code.PREC_F: Precipitation Flux from Cpl (rain+snow)
Thanks for the note Jonas.
Click to expand...
Hello, do you have a reference case for salinity budget analysis?
 
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