I am running QPC 6 compset CESM 2.1.3. I want to introduce water mountains in some specific regions. Which file and what modifications are required for this?
Thanks.
Sujatra
Thanks.
Sujatra
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How to introduce water mountains in Aquaplanet CESM CAM 6?
- Thread starter sujatra1bht
- Start date
"Water mountains" are topographical features added to a water-covered aquaplanet configuration. The surface is elevated, but is not represented by a land surface model.
You will need to specify a topography file that has the surface geopotential (PHIS).
In user_nl_cam, add an entry to specify to use a topo file and to the topo file itself:
use_topo_file = .true.
bnd_topo = '/path/to/file'
You can see example topo files for realistic set ups here: /glade/campaign/cesm/cesmdata/inputdata/atm/cam/topo
If you use this topography with the usual specified SST in QPC6, also consider adjusting the SST to account for the topography. I believe a recent example is given by:
Kim, H., Benedict, J.J., 2023. The Idealized Aquaplanet Maritime Continent Barrier Effect on the MJO Predictability. J. Clim. 36, 5757–5773. https://doi.org/10.1175/JCLI-D-22-0155.1
You will need to specify a topography file that has the surface geopotential (PHIS).
In user_nl_cam, add an entry to specify to use a topo file and to the topo file itself:
use_topo_file = .true.
bnd_topo = '/path/to/file'
You can see example topo files for realistic set ups here: /glade/campaign/cesm/cesmdata/inputdata/atm/cam/topo
If you use this topography with the usual specified SST in QPC6, also consider adjusting the SST to account for the topography. I believe a recent example is given by:
Kim, H., Benedict, J.J., 2023. The Idealized Aquaplanet Maritime Continent Barrier Effect on the MJO Predictability. J. Clim. 36, 5757–5773. https://doi.org/10.1175/JCLI-D-22-0155.1
Hi,
Thanks for your reply. I have tried to do the procedure as you mentioned. However, I am getting an error " Lagrangian levels crossing" and "suggest to increase NSPLTVRM". I have tried to increase NSPLTVRM from 0 to 2 and then 8 (Here I have also changed NSPLIT=32 and NSPLTRAC=16). But, it is still giving the same error. How to solve this error??
Thanks.
Sujatra
Thanks for your reply. I have tried to do the procedure as you mentioned. However, I am getting an error " Lagrangian levels crossing" and "suggest to increase NSPLTVRM". I have tried to increase NSPLTVRM from 0 to 2 and then 8 (Here I have also changed NSPLIT=32 and NSPLTRAC=16). But, it is still giving the same error. How to solve this error??
Thanks.
Sujatra
When I have seen that error in aquaplanet configurations, it has usually been because of an inconsistency between the initial condition and the model configuration. In this case, the initial condition might be for an aquaplanet with no topography, and then the model starts suddenly with topography, compressing the atmospheric columns and making strong pressure gradients. The dynamics tries to adjust, but the situation is too unstable (thus the recommendation to reduce nspltvrm).
One thing you could try would be to start from analytic, uniform initial conditions. To do that, add this to your user_nl_cam:
analytic_ic_type = 'us_standard_atmosphere'
And run this command to change the CAM configure options:
./xmlchange --append CAM_CONFIG_OPTS=-analytic_ic
When starting from idealized initial conditions, the circulation will need to spin up. That is pretty fast in an aquaplanet, but will take a few simulated days, and things may not be fully in their steady state for a few tens of days.
One thing you could try would be to start from analytic, uniform initial conditions. To do that, add this to your user_nl_cam:
analytic_ic_type = 'us_standard_atmosphere'
And run this command to change the CAM configure options:
./xmlchange --append CAM_CONFIG_OPTS=-analytic_ic
When starting from idealized initial conditions, the circulation will need to spin up. That is pretty fast in an aquaplanet, but will take a few simulated days, and things may not be fully in their steady state for a few tens of days.
Thanks for your reply. I was trying this. However, while building, I am getting the following error.
ERROR: in validate_variable_value (package Build::Namelist): Variable name analytic_ic_type has values that does NOT match any of the valid values: 'none' 'held_suarez_1994' 'moist_baroclinic_wave_dcmip2016' 'dry_baroclinic_wave_dcmip2016' 'dry_baroclinic_wave_jw2006'.
The Namelist variable 'us_standard_atmosphere' is not present for CESM version 2.1.3. Is it possible to add?
ERROR: in validate_variable_value (package Build::Namelist): Variable name analytic_ic_type has values that does NOT match any of the valid values: 'none' 'held_suarez_1994' 'moist_baroclinic_wave_dcmip2016' 'dry_baroclinic_wave_dcmip2016' 'dry_baroclinic_wave_jw2006'.
The Namelist variable 'us_standard_atmosphere' is not present for CESM version 2.1.3. Is it possible to add?
In these water mountain experiments, there is top
ography but no representation of the land surface. For significant topographical features, some modification of the surface temperature is needed, as noted above. With some accommodation for the surface temperature, the result is that the topographic feature(s) included mainly represent the mechanical forcing on the flow. For example:
Maroon, E. A., D. M. W. Frierson, and D. S. Battisti, 2015: The Tropical Precipitation Response to Andes Topography and Ocean Heat Fluxes in an Aquaplanet Model. J. Climate, 28, 381–398, The Tropical Precipitation Response to Andes Topography and Ocean Heat Fluxes in an Aquaplanet Model.
Similar thinking can be applied in other contexts ... some examples:
Boos, W.R., Pascale, S. Mechanical forcing of the North American monsoon by orography. Nature 599, 611–615 (2021). Mechanical forcing of the North American monsoon by orography - Nature
Sandu, I., van Niekerk, A., Shepherd, T.G. et al. Impacts of orography on large-scale atmospheric circulation. npj Clim Atmos Sci 2, 10 (2019). Impacts of orography on large-scale atmospheric circulation - npj Climate and Atmospheric Science
Welch, W. T., P. Smolarkiewicz, R. Rotunno, and B. A. Boville, 2001: The Large-Scale Effects of Flow over Periodic Mesoscale Topography. J. Atmos. Sci., 58, 1477–1492, https://doi.org/10.1175/1520-0469(2001)058<1477:TLSEOF>2.0.CO;2.
ography but no representation of the land surface. For significant topographical features, some modification of the surface temperature is needed, as noted above. With some accommodation for the surface temperature, the result is that the topographic feature(s) included mainly represent the mechanical forcing on the flow. For example:
Maroon, E. A., D. M. W. Frierson, and D. S. Battisti, 2015: The Tropical Precipitation Response to Andes Topography and Ocean Heat Fluxes in an Aquaplanet Model. J. Climate, 28, 381–398, The Tropical Precipitation Response to Andes Topography and Ocean Heat Fluxes in an Aquaplanet Model.
Similar thinking can be applied in other contexts ... some examples:
Boos, W.R., Pascale, S. Mechanical forcing of the North American monsoon by orography. Nature 599, 611–615 (2021). Mechanical forcing of the North American monsoon by orography - Nature
Sandu, I., van Niekerk, A., Shepherd, T.G. et al. Impacts of orography on large-scale atmospheric circulation. npj Clim Atmos Sci 2, 10 (2019). Impacts of orography on large-scale atmospheric circulation - npj Climate and Atmospheric Science
Welch, W. T., P. Smolarkiewicz, R. Rotunno, and B. A. Boville, 2001: The Large-Scale Effects of Flow over Periodic Mesoscale Topography. J. Atmos. Sci., 58, 1477–1492, https://doi.org/10.1175/1520-0469(2001)058<1477:TLSEOF>2.0.CO;2.