RRTMGP gas_optics() pressure range error in CESM3_beta07 with MERRA2 nudging

Liyl2

Yali Li
New Member
Hello, I am running CESM3_beta07 with the FCnudged_HCO compset at f19_f19_mg17 resolution. I am conducting an atmosphere simulation nudged toward MERRA2 meteorological fields. My nudging configuration is:
1788145151854.png

However, the model stops during the radiation calculation with the following error:
1788144561549.png

Initially, the simulation could not proceed without a pressure tolerance, so I introduced a 5% upper tolerance relative to press_ref_max. With this tolerance, the simulation ran for approximately 2.5 years before failing again. At the time of failure, max(play) slightly exceeded the upper limit, I am unsure whether it is physically and numerically appropriate to increase this tolerance further, or what effect doing so might have on the RRTMGP radiation calculation.

I also compared three nudging configurations. The free-running simulation without meteorological nudging did not encounter this error. When only the horizontal winds (U and V) were nudged, the pressure-range error occurred after only a few simulation days. When U, V, and temperature (T) were nudged together, the simulation ran for approximately 2.5 years before the same error occurred. These results suggest that the error is associated with the nudging configuration, although temperature nudging appears to delay its onset substantially.

The MERRA2 forcing data at 1.9° × 2.5° resolution were downloaded directly from the NSF NCAR GDEX dataset d313003. Since the free-running simulation does not encounter this error, I would like to understand why nudging causes play to exceed the RRTMGP pressure limit. Is increasing the pressure tolerance appropriate, and could it affect the accuracy of the radiation calculation? I would also appreciate any advice on the recommended way to address this issue. Thanks in advance!
 

patc

Patrick Callaghan
New Member
Hi Yali,

There are two nudging methodologies for the FV dycore. The namelist entries you have set up control
physics-side nudging, where the nudging tendencies are computed and applied on the physics grid.
An alternative method, the one activated by using the FCnudged_HCO compset, was implemented by folks
over at ACOM and applies nudging inside the FV dycore on the dynamics grid. For this case, the nudging
is controlled by the values in the &metdata_nl namelist. Unfortunately there is no constraint preventing your
set up where both nudging methods are applied at the same time.

--> Patrick
 
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Liyl2

Yali Li
New Member
Hi Yali,

There are two nudging methodologies for the FV dycore. The namelist entries you have set up control
physics-side nudging, where the nudging tendencies are computed and applied on the physics grid.
An alternative method, the one activated by using the FCnudged_HCO compset, was implemented by folks
over at ACOM and applies nudging inside the FV dycore on the dynamics grid. For this case, the nudging
is controlled by the values in the &metdata_nl namelist. Unfortunately there is no constraint preventing your
set up where both nudging methods are applied at the same time.

--> Patrick
Hi Patrick,

Thank you for the clarification. As I understand it, there are two alternative nudging approaches for the FV dycore:
  • Use the FCnudged_HCO compset and configure dynamics-side nudging through &metdata_nl:View attachment 7558
  • Use another active-atmosphere compset and enable physics-side nudging through &nudging_nl:View attachment 7559
Then,these two approaches should be used separately rather than simultaneously,Is my understanding correct? I also have a question about the FCSD compset. As I understand it, FCSD compset also uses &metdata_nl to constrain the FV dynamics. How does its specified-dynamics approach differ from the dynamics-side nudging used by FCnudged_HCO?

Thank you very much for your helpful response.

Best,
YaliView attachment 7559
 
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Liyl2

Yali Li
New Member
Hi Yali,

There are two nudging methodologies for the FV dycore. The namelist entries you have set up control
physics-side nudging, where the nudging tendencies are computed and applied on the physics grid.
An alternative method, the one activated by using the FCnudged_HCO compset, was implemented by folks
over at ACOM and applies nudging inside the FV dycore on the dynamics grid. For this case, the nudging
is controlled by the values in the &metdata_nl namelist. Unfortunately there is no constraint preventing your
set up where both nudging methods are applied at the same time.

--> Patrick
Hi Patrick,

Sorry, the images in my last message had some problems. Please see this version instead.
Thank you for the clarification. As I understand it, there are two alternative nudging approaches for the FV dycore:

1. Use the FCnudged_HCO compset and configure dynamics-side nudging through &metdata_nl:
&metdata_nl
met_data_file = '2018/MERRA2_1.9x2.5_20180101.nc'
met_data_path = '.../cesm_input/inputdata/atm/cam/met/MERRA2/1.9x2.5'
met_filenames_list = '.../cesm_input/inputdata/atm/cam/met/MERRA2/1.9x2.5/filenames_list_c180824.txt'
met_rlx_time = 6.0
met_nudge_temp = .false.
&nudging_nl
nudge_model = .false.

2. Use another active-atmosphere compset and enable physics-side nudging through &nudging_nl:
&nudging_nl
nudge_model = .true.
nudge_path = '.../cesm_input/inputdata/atm/cam/met/MERRA2/1.9x2.5/'
nudge_file_template = '%y/MERRA2_1.9x2.5_%y%m%d.nc'

nudge_beg_year = 2018
nudge_end_year = 2024
nudge_ucoef = 0.06
nudge_vcoef = 0.06

nudge_tcoef = 0.06
Then,these two approaches should be used separately rather than simultaneously,is my understanding correct?
I also have a question about the FCSD compset. As I understand it, FCSD compset also uses &metdata_nl to constrain the FV dynamics. How does its specified-dynamics approach differ from the dynamics-side nudging used by FCnudged_HCO?

Thank you very much for your helpful response.

Best,
Yali​
 
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