Query on regional SpinupStability threshold

[Arup]

Dear all,
I have attempted to test the spinup stability by following the forum guidelines. I found that for regional studies, it is necessary to adjust the threshold values, but I am unsure of the rationale behind these thresholds. In one forum thread (Questions about BGC spinup), I came across the concept of a scale factor, but could not understand the scaling factor based on the grid cells. Could you guide me on how to set up the scaling factor for studies focusing on my domain?

Attached below are the results using the default global threshold.

Copyright (C) 1995-2019 - All Rights Reserved
University Corporation for Atmospheric Research
NCAR Command Language Version 6.6.2
The use of this software is governed by a License Agreement.
See NCAR Command Language (NCL) for more details.
(0) =========================================
(0) Start Time: Wed Oct 23 23:47:41 IST 2024
(0) =========================================
warning:["CoordArrays.c":591]:No Valid values in Array, unable to compute Min or Max
warning:["CoordArrays.c":591]:No Valid values in Array, unable to compute Min or Max
(0) =======================================================================
(0) =======================================================================
(0) EQUILIBRIUM SUMMARY
(0) =======================================================================
(0) TOTECOSYSC is in equilibrium. Eq. Yr. = 1901
(0) TOTSOMC is in equilibrium. Eq. Yr. = 1901
(0) TOTVEGC is in equilibrium. Eq. Yr. = 1901
(0) TLAI is in equilibrium. Eq. Yr. = 1901
(0) GPP is in equilibrium. Eq. Yr. = 2001
(0) TWS is in equilibrium. Eq. Yr. = 1901
(0) WARNING: H2OSNO is NOT in equilibrium or is missing
(0) At least 97 percent of the land surface is in TOTECOSYSC equilibrium. Eq. Yr. = 2001
(0) Percent of the land surface not in equilibrium ( 0.60% )
(0) Congratulations! Your simulation is in equilibrium

 

[oleson]

As suggested in the post, a couple of ways to scale the thresholds is to use a ratio of number of land gridcells in the regional simulation to the number of land gridcells in the global simulation, or construct a ratio of area in the regional simulation to the global simulation. These are just suggestions, we don't have an established/robust way of doing it.

 

[Arup]

Thanks for the reply @oleson, I have adjusted the threshold by applying a scale factor based on the ratio of land grid cells in the regional simulation to those in the global simulation (i.e. 3795/259200). Below are the results after implementing these threshold changes.

Upon reviewing the results, it appears that the simulation hasn’t reached equilibrium, even though it had shown equilibrium with the global default threshold values. Could you advise if further adjustments are recommended for assessing regional stability, or do I need to run the model for more years to achieve equilibrium?

Thanks.

Copyright (C) 1995-2019 - All Rights Reserved
University Corporation for Atmospheric Research
NCAR Command Language Version 6.6.2
The use of this software is governed by a License Agreement.
See NCAR Command Language (NCL) for more details.
(0) =========================================
(0) Start Time: Fri Oct 25 23:23:20 IST 2024
(0) =========================================
warning:["CoordArrays.c":591]:No Valid values in Array, unable to compute Min or Max
warning:["CoordArrays.c":591]:No Valid values in Array, unable to compute Min or Max
(0) =======================================================================
(0) =======================================================================
(0) EQUILIBRIUM SUMMARY
(0) =======================================================================
(0) FATAL: TOTECOSYSC is NOT in equilibrium
(0) FATAL: TOTSOMC is NOT in equilibrium
(0) FATAL: TOTVEGC is NOT in equilibrium
(0) FATAL: TLAI is NOT in equilibrium
(0) FATAL: GPP is NOT in equilibrium
(0) WARNING: TWS is NOT in equilibrium or is missing
(0) WARNING: H2OSNO is NOT in equilibrium or is missing
(0) FATAL: Not enough of the land surface is in equilibrium ( 90.68% > 0.00%)
(0) FATAL: Your simulation is not in equilibrium, 8 hours have been deducted from your PTO bank, try again
(0) =======================================================================
(0) =========================================
(0) Finish Time: Fri Oct 25 23:23:22 IST 2024
(0) =========================================

 

[slevis]

If I saw 90% of the land surface NOT in equilibrium, I would opt in favor of running longer, and likely much longer.