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What's the consequence of modifying mean sea level pressure but without modifying surface pressure in WPS inputs?

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Z

zeyuxue

New member
Hi all,

WPS requires both surface pressure and sea level pressure as its inputs; however, in reviewing pseudo-global warming studies using WRF, I found some papers only modify mean sea level pressure by the changes indicated by CMIP projections but keep surface pressure as its original values. I'm thinking why those studies do not modify the surface pressure. Will the WPS or WRF adjust the surface pressure according to modified mean sea level pressure?

Thank you very much for your help!

Bests,
Zeyu
 
Hi Zeyu,
WRF REAL program does the surface pressure adjustment.
(1) if you have both PSFC and PMSL as input, REAL will recalculate PSFC based on these input data and SOILGHT
(2) if you only have PMSL, REAL will calculate PSFC based on WRF terrain , PMSL and other input variables like temperature.

To answer your question, I am thinking that you can change PMSL in your sensitivity experiment, but don't provide PSFC and let REAL calculate PSFC for you.
 
Hi Ming,

Got it! By the way, in the case WRF calculates moisture fluxes by the specific humidity and wind, is it necessary to include the moisture source and low-pressure center (or other essential features of storms) within the simulation domain?

Thank you so much for your kind help!

Bests,
Zeyu
 
Zeyu,
yes I believe that you should include those information in your input data, which will be ingested into the initial condition of WRF.
 
Hi Ming,

Got it! In my PGW simulation with both PSFC and PMSL as input but modified surface and 3d temperature and PMSL with the deltas from CMIP, I found the PMSL deltas of my PGW simulation have deltas with different magnitude and signs compared with the deltas from CMIP (the one I used to modify boundary conditions). Is it a result that WRF adjusts PMSL based on fixed PSFC and modified temperature? Why the WRF gets different PMSL simulation as its boundary conditions.

Thanks again for your help!

Bests,
Zeyu
 
Hi Zeyu,
you are right that the PMSL is a result of WRF adjustment based on fixed PSFC and modified temperature. WRF needs PMSL, PSFC and temperature to address the difference in terrain elevation between the forcing data and WRF itself, which will reduce the errors introduced during the vertical interpolation.
 
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