WRF sensitivity to cold start and restart

[YuanSUN]

Hi all,

I ran one WRF-CTSM simulation for 2022 and tried to examine the period for the 16-19 July 2022 heatwave. I conducted one sensitivity test on the initial conditions.

CNTL: 16-19 July, using wrfrst_d01_2022-07-16 restart.
COLD: 7-19 July, using 10-day spinup from 7-16 July by cold start, and 16-19 for analysis.

I found the COLD case has a lower atmospheric temperature at the bottom layer compared to CNTL by 1°C. The land surface is also cooler.

Is it a normal condition? How to explain it?

Thanks for any insights.

Best,
Yuan

 

[Ming Chen]

Yuan,

Where did you get WRF-CTSM? I suppose it is not an official release of WRF. Let me kknow if I am wrong.

For your CNTL and COLD tests, please confirm that both tests run with identical physics and dynamics options and driven by same forcing data.

You also need to check wrfrst_d01_2022-07-16, and compare it with wrfout_d01_2022-07-16 from COLD. The two files should be bit-for-bit identical. if not, I guess something could be wrong in the model system.

 

[YuanSUN]

Yuan,

Where did you get WRF-CTSM? I suppose it is not an official release of WRF. Let me kknow if I am wrong.

For your CNTL and COLD tests, please confirm that both tests run with identical physics and dynamics options and driven by same forcing data.

You also need to check wrfrst_d01_2022-07-16, and compare it with wrfout_d01_2022-07-16 from COLD. The two files should be bit-for-bit identical. if not, I guess something could be wrong in the model system.

Hi Ming,

Thanks for your response. CTSM is officially incorperated in WRF as a land surface scheme. Please refer to WRF/phys/module_sf_ctsm.F at master · wrf-model/WRF and https://doi.org/10.1029/2024JD043103

Based on your suggestion, I plotted the T2 on 7 July and found that the COLD case has a lower surface temperature. CTSM's initial condition causes this. I replaced the initial condition and ran a new simulation now.

Best,
Yuan

 

[Ming Chen]

Hi Yuan,

Thank you for the clarification. Please keep me updated about your results of the new test.

We don't frequently use CTSM land surface scheme because it doesn't work for nesting cases. Therefore we don't have many experiences with this scheme. Your input will be helpful for us to better understand its performance. Thank you.