Surface salinity drift in BLOM

[adagj]

The Arctic is too fresh in BLOM - to be discussed here

[JorgSchwinger]

As shown in NorESMhub/NorESM#700, there is too much runnoff, probably linked to too little latent heat fluxes over land, and probably some contribution due to spin-up issues of the land-hydrologly.

@kjetilaas , do we already have a coupled test simulation of how the new parameter settings for CLM that increase LH-fluxes play out?

[adagj]

@JorgSchwinger @matsbn @JensBDebernard
I compared the freshwater terms in The Arctic Ocean for the latest beta02 simulations

• [PINK: NorESM2-LM]
• BLUE: beta02
• ORANGE: NOSIP beta02: Secondary ice production = .false.
• GREEN: CLM INIT beta02Old CLM inital file

To me it seems like the melting/freezing term (fmltfz) exhibits a very strong trend in the Beta02 simulations. I see that Mats started a new spinup of ocean and sea ice yeaterday (#233). Should we adress this? The precipitation trend is much reduced in the NOSIP simulation...

[JorgSchwinger]

Hi @adagj

from what I have plotted here NorESMhub/NorESM#700 (comment) the freeze/melt freshwater-fluxes do not look suspicious.

I still hope that increasing LH-fluxes over land, better spun-up land initial conditions, and the secondary ice bug fix will improve the salinity drift in the Arctic.

[JorgSchwinger]

The Arctic surface salinity bias is clearly better (compared to beta01) in beta03 with the secondary ice fix:

Otherwise little change. Let's hope that the remaining Arctic bias goes away with improved latent heat fluxes on land...